Monday, April 30, 2007

The Myth of Mirror Neurons?

In an article in a special issue of Slate devoted to the brain (well worth checking over...I'll give some links to articles in the Slate issue in subsequent posts), Gopnik argues that excitement over the discovery of mirror neurons in our brains (the subject of a number of blog posts and my lecture posted earlier...) is generating a new scientific myth. Like a traditional myth, it captures intuitions about the human condition through vivid metaphors. Some clips:

It didn't take long for scientists and science writers to speculate that mirror neurons might serve as the physiological basis for a wide range of social behaviors, from altruism to art appreciation. Headlines like "Cells That Read Minds" or "How Brain's 'Mirrors' Aid Our Social Understanding" tapped into our intuitions about connectedness. Maybe this cell, with its mellifluous name, gives us our special capacity to understand one another—to care, to learn, and to communicate. Could mirror neurons be responsible for human language, culture, empathy, and morality?.

The evidence for individual mirror neurons comes entirely from studies of macaque monkeys. That's because you can't find these cells without inserting electrodes directly (though painlessly) into individual neurons in the brains of living animals. These studies haven't been done with chimpanzees, let alone humans.

The trouble is that macaque monkeys don't have language, they don't have culture, and they don't understand other animals' minds. In fact, careful experiments show that they don't even systematically imitate the actions of other monkeys—and they certainly don't imitate in the prolific way that the youngest human children do. Even chimpanzees, who are much more cognitively sophisticated than macaques, show only very limited abilities in these areas. The fact that macaques have mirror neurons means that these cells can't by themselves explain our social behavior.

This week's recording - Arabesque

Debussy's first Arabesque, recorded on my Steinway B in Middleton Wisconsin.

Top-Down/Bottom-Up in Attention Control

An elegant study from Buschman and Miller. Their abstract:

Attention can be focused volitionally by "top-down" signals derived from task demands and automatically by "bottom-up" signals from salient stimuli. The frontal and parietal cortices are involved, but their neural activity has not been directly compared. Therefore, we recorded from them simultaneously in monkeys. Prefrontal neurons reflected the target location first during top-down attention, whereas parietal neurons signaled it earlier during bottom-up attention. Synchrony between frontal and parietal areas was stronger in lower frequencies during top-down attention and in higher frequencies during bottom-up attention. This result indicates that top-down and bottom-up signals arise from the frontal and sensory cortex, respectively, and different modes of attention may emphasize synchrony at different frequencies.

Friday, April 27, 2007

Does Darwinism have to be depressing?

Robert Wright, author of "The Moral Animal," argues no, in spite of the fact that evolutionary explanations boil our loftiest feelings boil down to genetic self-interest. Morality, along with love and positive emotions, are your genes way of getting you to serve their agenda. Here is a PDF of his essay.

Which way are you wagging your tail?

Blakeslee writes a review (PDF here) of work by Vallortigara et al (PDF here) on emotional asymmetric tail wagging by dogs that is a further reflection of lateralized functions of the brain. Some edited clips from her article:

In most animals, including birds, fish and frogs, the left brain specializes in behaviors involving what the scientists call approach and energy enrichment. In humans, that means the left brain is associated with positive feelings, like love, a sense of attachment, a feeling of safety and calm. It is also associated with physiological markers, like a slow heart rate.

At a fundamental level, the right brain specializes in behaviors involving withdrawal and energy expenditure. In humans, these behaviors, like fleeing, are associated with feelings like fear and depression. Physiological signals include a rapid heart rate and the shutdown of the digestive system.

Because the left brain controls the right side of the body and the right brain controls the left side of the body, such asymmetries are usually manifest in opposite sides of the body. Thus many birds seek food with their right eye (left brain/nourishment) and watch for predators with their left eye (right brain/danger).

In humans, the muscles on the right side of the face tend to reflect happiness (left brain) whereas muscles on the left side of the face reflect unhappiness (right brain).

Dog tails are interesting...because they are in the midline of the dog’s body, neither left nor right. So do they show emotional asymmetry, or not?

Vallortigara et al show that when dogs were attracted to something, including a benign, approachable cat, their tails wagged right, and when they were fearful, their tails went left. It suggests that the muscles in the right side of the tail reflect positive emotions while the muscles in the left side express negative ones.

Brain asymmetry for approach and withdrawal seems to be an ancient trait..Thus it must confer some sort of survival advantage on organisms.

Animals that can do two important things at the same time, like eat and watch for predators, might be better off. And animals with two brain hemispheres could avoid duplication of function, making maximal use of neural tissue.

The asymmetry may also arise from how major nerves in the body connect up to the brain... Nerves that carry information from the skin, heart, liver, lungs and other internal organs are inherently asymmetrical, he said. Thus information from the body that prompts an animal to slow down, eat, relax and restore itself is biased toward the left brain. Information from the body that tells an animal to run, fight, breathe faster and look out for danger is biased toward the right brain.

Thursday, April 26, 2007

Crisis in connectivity

I realized yet again how much my high speed internet access has become a part of my extended ego when on returning to Madison WI from Ft. Lauderdale FL it took the better part of a week for me to get DSL, cable modem, wireless router, etc. back up and running again. During the down period I began to empathize more with what people must go through in drug withdrawal, a vital craving was not being satisfied.

In this light I enjoyed reading the account of people reacting to a recent 12 hour shutdown of the Blackberry messaging network (PDF here)

...what if what the users were missing was more primitive and insidious than
uninterrupted access to information?...the stated yearning to stay abreast of things may mask more visceral and powerful needs, as many self-aware users themselves will attest. Seductive, nearly inescapable needs...constant use becomes ritualistic physical behavior, even addiction, the absorption of nervous energy, like chomping gum...This behavior is then fueled by powerful social motivators. Interaction with a device delivering data gives a feeling of validation, inclusion and desirability....“acquired attention deficit disorder” ... [can] describe the condition of people who are accustomed to a constant stream of digital stimulation and feel bored in the absence of it. Regardless of whether the stimulation is from the Internet, TV or a cellphone, the brain... is hijacked.

Is recursion a universal aspect of languages?

The april 16 issue of The New Yorker magazine has an engaging essay (titled "The Interpreter") by John Colapinto describing the work of Dan Everett and others with the Piraha people of the Amazon. Since they were found in the 1700s, they have rejected everything from outside their world. They use one of the simplest language sound systems known. There are just eight consonants and three vowels, yet it possesses such a complex array of tones, stresses, and syllable lengths that its speakers can dispense with their vowels and consonants altogether and sing, hum, or whistle conversations (using what the linguists call "prosody"). The Piraha have no numbers, no fixed color terms, no perfect tense, no deep memory, no tradition of art of drawing, and no words for "all," "each," "every,""most," or "few" which some linguists take to be among the common building blocks of human cognition. They have a "one,""two," and "many" counting system and concerted teaching efforts fail to teach them to count to higher numbers. Everett thinks that the tribe embodies a living-in-the-present ethos so powerful that if affects every aspect of their lives. Committed to an existence in which only observable experience is real, the Priaha do not think, or speak, in abstractions - and thus do not use color terms, quantifiers, numbers, or myths.

Everett claims that their language lacks any evidence of recursion, which Hauser, Chomsky, and Fitch declared, in an influential 2002 paper in Science, to be the distinctive feature of the human faculty of language. He argues that recursion (embedding entities within entities) is primarily a cognitive, not a linguistic, trait. Many complex structures (like Microsoft Word) are organized into tree structures. Piraha appears to be a language that has phonology, morphology, syntax, and sentences, but no recursion.

Colapinto's article describes Fitch's visit with Evertt to the Priaha to perform tests trying to find any evidence for their recursive abilities. His results were largely inconclusive.

Wednesday, April 25, 2007

What Determines Winners?

Experts in the entertainment industry and many other fields put great effort into predicting what people will like, what will sell. Great effort goes into researching people's tastes and preferences. In spite of this, predicted big hits frequently crash, while unknown songs or movies can rise from nowhere to become wildly popular. Interesting experiments done by Salganik, Dodds and Watts. (PDF here) suggest a reason for this failure in prediction: People do not make decisions about what they like independently of each other, but rather tend to like what they see other people liking. Here are some edited clips from a review of the work written by Watts:

..differences in popularity are subject to what is called “cumulative advantage,” or the “rich get richer” effect. This means that if one object happens to be slightly more popular than another at just the right point, it will tend to become more popular still. As a result, even tiny, random fluctuations can blow up, generating potentially enormous long-run differences among even indistinguishable competitors — a phenomenon that is similar in some ways to the famous “butterfly effect” from chaos theory. Thus, if history were to be somehow rerun many times, seemingly identical universes with the same set of competitors and the same overall market tastes would quickly generate different winners: Madonna would have been popular in this world, but in some other version of history, she would be a nobody, and someone we have never heard of would be in her place.
To examine how cumulative advantage might work, a website set up by the authors recruited 14,341 participants to listen to, rate, and, if they chose download songs by bands they had never heard.
Some of the participants saw only the names of the songs and bands, while others also saw how many times the songs had been downloaded by previous participants. This second group — in what they called the “social influence” condition — was further split into eight parallel “worlds” such that participants could see the prior downloads of people only in their own world. We didn’t manipulate any of these rankings — all the artists in all the worlds started out identically, with zero downloads — but because the different worlds were kept separate, they subsequently evolved independently of one another.
In this artifical market one song ranked 26th out of 48 in quality; yet it was the No. 1 song in one social-influence world, and 40th in another. Overall, a song in the Top 5 in terms of quality had only a 50 percent chance of finishing in the Top 5 of success.
...social influence played as large a role in determining the market share of successful songs as differences in quality. It’s a simple result to state, but it has a surprisingly deep consequence. Because the long-run success of a song depends so sensitively on the decisions of a few early-arriving individuals, whose choices are subsequently amplified and eventually locked in by the cumulative-advantage process, and because the particular individuals who play this important role are chosen randomly and may make different decisions from one moment to the next, the resulting unpredictably is inherent to the nature of the market. It cannot be eliminated either by accumulating more information — about people or songs — or by developing fancier prediction algorithms, any more than you can repeatedly roll sixes no matter how carefully you try to throw the die.

This lesson is not limited to cultural products either. Economists like Brian Arthur and Paul David have long argued that similar mechanisms affect the competition between technologies (like operating systems or fax machines) that display what are called “network effects,” meaning that the attractiveness of a technology increases with the number of people using it...even a modest amount of randomness can play havoc with our intuitions. Because it is always possible, after the fact, to come up with a story about why things worked out the way they did — that the first “Harry Potter” really was a brilliant book, even if the eight publishers who rejected it didn’t know that at the time — our belief in determinism is rarely shaken, no matter how often we are surprised. But just because we now know that something happened doesn’t imply that we could have known it was going to happen at the time, even in principle, because at the time, it wasn’t necessarily going to happen at all.

Protocol based architectures.

Doyle and Csete offer an interesting essay on "Rules of Engagement" in the recent issue of Nature Magazine. (PDF here). Their summary:

Complex engineered and biological systems share protocol-based architectures that make them robust and evolvable, but with hidden fragilities to rare perturbations.
They draw an analogy between the protocol based architecture (TCP/IP) of the internet and transcription and translation protocols that regulate the horizontal transfer of genes between organisms.

Tuesday, April 24, 2007

Evolution and Brain science shaping public discourse

I want to mention and pass on two recent Op-Ed columns of David Brooks in the New York Times. He has done a commendable job of learning the basic ideas in evolution and brain science and passing them on in a clear and palatable way.

Here are some clips from the first, titled "The Age of Darwin" (PDF here).

Once the Bible shaped all conversation, then Marx, then Freud, but today Darwin is everywhere... Scarcely a month goes by when Time or Newsweek doesn’t have a cover article on how our genes shape everything from our exercise habits to our moods. Science sections are filled with articles on how brain structure influences things like lust and learning. Neuroscientists debate the existence of God on the best-seller lists, while evolutionary theory reshapes psychology, dieting and literary criticism. Confident and exhilarated, evolutionary theorists believe they have a universal framework to explain human behavior...Creationists reject the whole business, but they’re like the Greeks who still worshiped Athena while Plato and Aristotle practiced philosophy. The people who set the cultural tone today have coalesced around a shared understanding of humanity and its history that would have astonished people in earlier epochs....According to this view, human beings, like all other creatures, are machines for passing along genetic code. We are driven primarily by a desire to perpetuate ourselves and our species.

The logic of evolution explains why people vie for status, form groups, fall in love and cherish their young. It holds that most everything that exists does so for a purpose. If some trait, like emotion, can cause big problems, then it must also provide bigger benefits, because nature will not expend energy on things that don’t enhance the chance of survival...Human beings, in our current understanding, are jerry-built creatures, in which new, sophisticated faculties are piled on top of primitive earlier ones. Our genes were formed during the vast stretches when people were hunters and gatherers, and we are now only semi-adapted to the age of nuclear weapons and fast food. Furthermore, reason is not separate from emotion and the soul cannot be detached from the electrical and chemical pulses of the body. There isn’t even a single seat of authority in the brain. The mind emerges (somehow) from a complex light show of neural firings without a center or executive. We are tools of mental processes we are not even aware of.
The second essay, "The Morality Line," (PDF here) comments on the rush to assign responsibility for the recent killings at Virginia Tech by Cho Seung-Hui.
...over the past few decades, neuroscientists, evolutionary psychologists and social scientists have made huge strides in understanding why people — even murderers — do the things they do...It’s important knowledge, but it’s had the effect of reducing the scope of the human self...in the realm of the new science, the individual is like a cork bobbing on the currents of giant forces: evolution, brain chemistry, stress and upbringing. Human consciousness is merely an epiphenomena of the deep and controlling mental processes that lie within...the killings at Virginia Tech happen at a moment when we are renegotiating what you might call the Morality Line, the spot where background forces stop and individual choice — and individual responsibility — begins. The killings happen at a moment when the people who explain behavior by talking about biology, chemistry and social science are assertive and on the march, while the people who explain behavior by talking about individual character are confused and losing ground...And it’s true. We’re never going back. We’re not going to put our knowledge of brain chemistry or evolutionary psychology back in the bottle. It would be madness to think Cho Seung-Hui could have been saved from his demons with better sermons...There still seems to be such things as selves, which are capable of making decisions and controlling destiny. It’s just that these selves can’t be seen on a brain-mapping diagram, and we no longer have any agreement about what they are.

Neuron competition during memory formation.

Science Magazine summaries an article by Han et al. :

Electrophysiological and cellular imaging studies show that only a portion of neurons are involved in a given memory. Why is one neuron, rather than its neighbor, included in a particular memory? Han et al. ... found that neurons in the lateral amygdala that contain the highest levels of function of the transcription factor CREB at the time of the encoding of an auditory fear memory are those that preferentially express the activity-regulated gene Arc after the recall of the memory. Thus, neurons compete during memory formation, and CREB helps to determine the winners.

The abstract from Han et al. :
Competition between neurons is necessary for refining neural circuits during development and may be important for selecting the neurons that participate in encoding memories in the adult brain. To examine neuronal competition during memory formation, we conducted experiments with mice in which we manipulated the function of CREB (adenosine 3',5'-monophosphate response element–binding protein) in subsets of neurons. Changes in CREB function influenced the probability that individual lateral amygdala neurons were recruited into a fear memory trace. Our results suggest a competitive model underlying memory formation, in which eligible neurons are selected to participate in a memory trace as a function of their relative CREB activity at the time of learning.

Monday, April 23, 2007

Twin Valley Music - Debussy Reverie version II

Now that I'm back with my Steinway B at the house on Twin Valley Road in Middleton Wisconsin, I'm starting to resume recording and posting some of my playing. I am amazed that a recording of this Debussy Reverie that I posted on Aug 29 of last year has been viewed over 9,000 times and drawn 24 interesting and constructive comments. I've decided to respond to the comments - several of which said "slow down" - by recording and posting a version two of the reverie

The social power of groups regulates their variability

Here is the slightly edited abstract of a recent talk at the Univ. of Wisconsin by Markus Brauer, University de Clermont-Ferrand, "Social Power and With-Group Variability: The Mediating Roles of Disinhibition and Pressure to Conform."

People's perception of a group as rather homogeneous or heterogenous determines their tendency to apply stereotypes to that group. For this reason, many social scientists have been interested in "group variability," and the extent to which members of social groups are different from each other.... I present a series of correlational and experimental studies showing that members of high power (advantaged) groups are more different from each other than members of low power (disadvantaged) groups: they report more diverse preferences, they engage in more diverse behaviors, and ­ according on naive observers' judgments ­ they have more diverse character traits. In addition, I present data suggesting that the effect of social power on group variability is mediated by "pressures to conformity" and "disinhibition." We have shown that a norm transgressor in a high power group is reacted to less negatively by fellow in-group members than a norm transgressor who belongs to a low power group. Members of high power groups also behave in a more disinhibited manner in that they are more relaxed and are more willing to engage in potentially embarrassing activities. ... our work suggests that the need for affiliation is more salient for members of low power groups, whereas the need for differentiation is more important for members of high power groups.

Nyotaimori - the latest in thing for "Foodies"

Two items in the food section of the 4/18 New York Times cracked me up, and I had to pass them on. California food styles, like its governor Schwarzenegger, are far ahead of the pack...

A new restaurant opening in West Hollywood features Nyotaimori, associated in legend with Japanese organize crime, the term translating as "female body arrangement" (and - this being gay West Hollywood - prospective customers have also made inquiries about a male model being used instead of a woman). Rachael, the model:

was a human sushi platter for the evening, the centerpiece of an opening party last month for Hadaka Sushi on the Sunset Strip. Taking gentle breaths, she kept as still as possible so as not to disturb the clusters of oil-infused sushi rolls, sashimi and other pieces of raw fish artfully arranged on the banana leaves in a style known as nyotaimori.... [she]..seemed to enjoy the evening as much as anyone could while lying supine and being poked by chopsticks. To an onlooker, the most disturbing aspect of her job might be Hadaka’s rule that forbids a model to eat the sushi that rests inches away from her mouth.
Head up the California coast from LA to San Francisco and you have "Cafe Gratitude"
a raw-food restaurant in San Francisco, where every order is a self-affirmation — I Am Open, I Am Beautiful, I Am Powerful — mirrored back to you by your server....
“We invite you to step inside and enjoy being someone who chooses: loving your life, adoring yourself, accepting the world, being generous and grateful everyday, and experiencing being provided for.”

Wow. So. The appetizers: I Am Bountiful live crustini, “toasts” made from seeds and nuts with such toppings as avocado and not-so-local Himalayan salt. I Am Happy live almond-sesame hummus. (“Live” food has not been cooked above 118 degrees, the temperature that kills enzymes, and incorporates sprouting seeds and nuts.) I Am Insightful spinach-wrapped samosas with cauliflower and macadamia “potatoes.”...And on through the long menu: I Am Giving, I Am Festive, I Am Prosperous, I Am Fabulous, Yo Soy Mucho (Mexican bowl).

Friday, April 20, 2007

Representation of social concepts in superior anterior temporal cortex

An interesting bit of work from Zahn et al. Their abstract:

Social concepts such as "tactless" or "honorable" enable us to describe our own as well as others' social behaviors. The prevailing view is that this abstract social semantic knowledge is mainly subserved by the same medial prefrontal regions that are considered essential for mental state attribution and self-reflection. Nevertheless, neurodegeneration of the anterior temporal cortex typically leads to impairments of social behavior as well as general conceptual knowledge. By using functional MRI, we demonstrate that the anterior temporal lobe represents abstract social semantic knowledge in agreement with this patient evidence. The bilateral superior anterior temporal lobes (Brodmann's area 38) are selectively activated when participants judge the meaning relatedness of social concepts (e.g., honor–brave) as compared with concepts describing general animal functions (e.g., nutritious–useful). Remarkably, only activity in the superior anterior temporal cortex, but not the medial prefrontal cortex, correlates with the richness of detail with which social concepts describe social behavior. Furthermore, this anterior temporal lobe activation is independent of emotional valence, whereas medial prefrontal regions show enhanced activation for positive social concepts. Our results demonstrate that the superior anterior temporal cortex plays a key role in social cognition by providing abstract conceptual knowledge of social behaviors. We further speculate that these abstract conceptual representations can be associated with different contexts of social actions and emotions through integration with frontolimbic circuits to enable flexible evaluations of social behavior.

Legend - (click on figure to enlarge) Regions in which activity was higher for social than for animal concepts and that were independently correlated with descriptiveness of social behavior and meaning relatedness.

A bizarre story - the parasite that lets cats eat rats

From Sapolsky's lab at Stanford:

The protozoan parasite Toxoplasma gondii blocks the innate aversion of rats for cat urine, instead producing an attraction to the pheromone; this may increase the likelihood of a cat predating a rat. This is thought to reflect adaptive, behavioral manipulation by Toxoplasma in that the parasite, although capable of infecting rats, reproduces sexually only in the gut of the cat. The "behavioral manipulation" hypothesis postulates that a parasite will specifically manipulate host behaviors essential for enhancing its own transmission. However, the neural circuits implicated in innate fear, anxiety, and learned fear all overlap considerably, raising the possibility that Toxoplasma may disrupt all of these nonspecifically. We investigated these conflicting predictions. In mice and rats, latent Toxoplasma infection converted the aversion to feline odors into attraction. Such loss of fear is remarkably specific, because infection did not diminish learned fear, anxiety-like behavior, olfaction, or nonaversive learning. These effects are associated with a tendency for parasite cysts to be more abundant in amygdalar structures than those found in other regions of the brain. By closely examining other types of behavioral patterns that were predicted to be altered we show that the behavioral effect of chronic Toxoplasma infection is highly specific. Overall, this study provides a strong argument in support of the behavioral manipulation hypothesis. Proximate mechanisms of such behavioral manipulations remain unknown, although a subtle tropism on part of the parasite remains a potent possibility.

Thursday, April 19, 2007

Egalitarian motives in humans

Dawes et al. play some laboratory games that suggest important factors underlying the evolution of strong reciprocity and cooperation in humans, experiments that distinguish reward and punishment from egalitarian motives. Their abstract below and a PDF of the article here:

Participants in laboratory games are often willing to alter others' incomes at a cost to themselves, and this behaviour has the effect of promoting cooperation. What motivates this action is unclear: punishment and reward aimed at promoting cooperation cannot be distinguished from attempts to produce equality. To understand costly taking and costly giving, we create an experimental game that isolates egalitarian motives. The results show that subjects reduce and augment others' incomes, at a personal cost, even when there is no cooperative behaviour to be reinforced. Furthermore, the size and frequency of income alterations are strongly influenced by inequality. Emotions towards top earners become increasingly negative as inequality increases, and those who express these emotions spend more to reduce above-average earners' incomes and to increase below-average earners' incomes. The results suggest that egalitarian motives affect income-altering behaviours, and may therefore be an important factor underlying the evolution of strong reciprocity and, hence, cooperation in humans.

Bipolar disorder - related to a disorder in the Clock gene?

Coyle offers a review in the April 10 issues of PNAS of a paper by Roybal et al. showing that mutation of the clock gene in mice causes them to show symptoms of bipolar behavior. I give you Coyle's summary:

Bipolar disorder, also known as manic-depressive illness, is characterized by episodes of mania and episodes of depression usually interspersed with periods of relatively normal mood. During the manic phase, affected individuals exhibit elevated mood, irritability, increased activity, reduced sleep, hypersexuality, and increased goal-directed activities. Bipolar disorder in its various forms affects >3% of the population and is associated with a high risk for suicide, substance abuse, and vocational disability. Although several animal models for major depressive disorder have been developed, there are no plausible models for bipolar disorder. In this issue of PNAS, Roybal et al. describe the results of a systematic analysis of the behavior of a mouse with a deletion of exon 19 in the Clock gene, which shows remarkable parallels to the symptoms observed in individuals in an episode of mania. The Clock mutant mice exhibit hyperactivity, decreased sleep, reduced anxiety, and increased response to cocaine, sucrose, and medial forebrain bundle stimulation. Furthermore, many of these behaviors can be reversed by transfection of the ventral tegmental area (VTA) dopaminergic neurons with WT Clock gene or by treatment with therapeutic doses of lithium (Li+), a commonly prescribed mood stabilizer.

And the abstract of the article:
Circadian rhythms and the genes that make up the molecular clock have long been implicated in bipolar disorder. Genetic evidence in bipolar patients suggests that the central transcriptional activator of molecular rhythms, CLOCK, may be particularly important. However, the exact role of this gene in the development of this disorder remains unclear. Here we show that mice carrying a mutation in the Clock gene display an overall behavioral profile that is strikingly similar to human mania, including hyperactivity, decreased sleep, lowered depression-like behavior, lower anxiety, and an increase in the reward value for cocaine, sucrose, and medial forebrain bundle stimulation. Chronic administration of the mood stabilizer lithium returns many of these behavioral responses to wild-type levels. In addition, the Clock mutant mice have an increase in dopaminergic activity in the ventral tegmental area, and their behavioral abnormalities are rescued by expressing a functional CLOCK protein via viral-mediated gene transfer specifically in the ventral tegmental area. These findings establish the Clock mutant mice as a previously unrecognized model of human mania and reveal an important role for CLOCK in the dopaminergic system in regulating behavior and mood.

Wednesday, April 18, 2007

Enhanced Visuospatial Cognition in Musicians

Yet another piece on how the brains of musicans are different (I continue to be grateful for the apparent side effects of being a serious pianist). The whole title of the article by Sluming et al. is "Broca's Area Supports Enhanced Visuospatial Cognition in Orchestral Musicians"
Their (slightly stuffy) abstract:

We provide neurobehavioral evidence supporting the transferable benefit of music training to alter brain function and enhance cognitive performance in a nonmusical visuospatial task in professional orchestral musicians. In particular, orchestral musicians' performance on a three-dimensional mental rotation (3DMR) task exhibited the behavioral profile normally onlya attained after significant practice, supporting the suggestion that these musicians already possessed well developed neural circuits to support 3DMR. Furthermore, functional magnetic resonance imaging revealed that only orchestral musicians showed significantly increased activation in Broca's area, in addition to the well known visuospatial network, which was activated in both musicians and nonmusicians who were matched on age, sex, and verbal intelligence. We interpret these functional neuroimaging findings to reflect preferential recruitment of Broca's area, part of the neural substrate supporting sight reading and motor-sequence organization underpinning musical performance, to subserve 3DMR in musicians. Our data, therefore, provide convergent behavioral and neurofunctional evidence supporting the suggestion that development of the sight-reading skills of musical performance alters brain circuit organization which, in turn, confers a wider cognitive benefit, in particular, to nonmusical visuospatial cognition in professional orchestral musicians.

The Primate Lineage

Two items on primates:

John Noble Wilford does a nice review of the recent primatology meeting in Chicago in the NY Times science section 4/17/07. His emphasis is on recent work with Chimps, showing them to be social creatures that appear to be capable of empathy, altruism, self-awareness, cooperation in problem solving and learning through example and experience. PDF is here.

The April 13 issue of Science Magazine has a series of articles on the sequencing of the genome of the rhesus macaque monkey. This begins to put the previously sequenced chimp and human genomes into perspective. Macaques are Old World monkeys, which split perhaps 25 million years ago from the ape lineage that led to both chimpanzees and humans. I thought I would pass on this graphic from from Pennisi's article showing the primate evolutionary line.

Researchers plan to eventually sequence the genomes of all these primates and related species, with human, macaque, and chimp now published. The animals are arranged in an artist's rendition of their family tree, with estimated divergence dates in millions of years. CREDITS: (ILLUSTRATION) N. KEVITIYAGALA/SCIENCE; (ADAPTED FROM) E. EIZIRIK ET AL., IN ANTHROPOID ORIGINS: NEW VISIONS, C. F. ROSS AND R. F. KAY (KLUWER/PLENUM, 2004), PP. 45-64.

Tuesday, April 17, 2007

Amygdala damage impairs eye contact

Here is the abstract of an article from Adolph's group at Cal. Tech.:

The role of the human amygdala in real social interactions remains essentially unknown, although studies in nonhuman primates and studies using photographs and video in humans have shown it to be critical for emotional processing and suggest its importance for social cognition. We show here that complete amygdala lesions result in a severe reduction in direct eye contact during conversations with real people, together with an abnormal increase in gaze to the mouth. These novel findings from real social interactions are consistent with an hypothesized role for the amygdala in autism and the approach taken here opens up new directions for quantifying social behavior in humans.
And a clip from their discussion:
It is intriguing ...to consider similarities between our findings and those in autism. People with autism do not fixate photographs and videos of faces normally, and are anecdotally reported to gaze at the mouth in social interactions. It has been suggested that the amygdala dysfunction is in part to blame for these abnormalities in autism, and recent findings using neuroimaging with photographs of faces support this hypothesis.

Sexual Desire

Natalie Angier writes an engaging review of research into factors regulating sexual desire and sexual arousal (PDF here). The Science section of the April 10 New York Times contains a number of other interesting articles on sex and desire.


One brief edited clip from Angier:

According to the sequence put forward in the mid-20th century by the pioneering sex researchers William H. Masters, Virginia E. Johnson and Helen Singer Kaplan, a sexual encounter begins with desire, a craving for sex that arises of its own accord and prods a person to seek a partner. That encounter then leads to sexual arousal, followed by sexual excitement, a desperate fumbling with buttons and related clothing fasteners, a lot of funny noises, climax and resolution...A plethora of new findings, however, suggest that the experience of desire may be less a forerunner to sex than an afterthought, the cognitive overlay that the brain gives to the sensation of already having been aroused by some sort of physical or subliminal stimulus — a brush on the back of the neck, say, or the sight of a ripe apple, or wearing a hard hat on a construction site and being surrounded by other men in similar haberdashery.

In a series of studies at the University of Amsterdam, Ellen Laan, Stephanie Both and Mark Spiering demonstrated that the body’s entire motor system is activated almost instantly by exposure to sexual images, and that the more intensely sexual the visuals, the stronger the electric signals emitted by the participants’ so-called spinal tendious reflexes. By the looks of it, Dr. Laan said, the body is primed for sex before the mind has had a moment to leer.... arousal is not necessarily a conscious process. In other experiments... when college students were exposed to sexual images too fleetingly for the subjects to report having noticed them, the participants were nevertheless much quicker to identify subsequent sexual images than were the control students who had been flashed with neutral images.

By reordering the sexual timeline and placing desire after arousal, rather than vice versa, the new research fits into the pattern that neurobiologists have lately observed for other areas of life. Before we are conscious of wanting to do anything — wave at a friend, open a book — the brain regions needed to perform the activity are already ablaze. The notion that any of us is the Decider, the proactive plotter of our most lubricious desires, scientists say, may simply be a happy and perhaps necessary illusion.
This is precisely the message of my I-Illusion essay on this website.

Monday, April 16, 2007

Gregariousness of early-adolescent mice influenced by genetic background

Panskepp et al have studied two inbred mouse strains whose infants on weaning show high versus low levels of gregarious social behavior, They controlled a host of behavioral variables during the course of adolescent development to demonstrate specific differences in social motivations among juveniles of the two mouse strains — behavioral variations that could only be explained by genetic differences. Young mice from the gregarious strain seek environments that predict the possibility of a social encounter and avoid places where they have experienced social isolation. The review by Devitt edited for this post quotes the senior author Lahvis: "There is an association between high-pitched calls in mice and positive experience. The quality and quantity of the call are tightly associated with the nature of the interaction itself."

As the mice neared sexual maturity, the genetic influence on social behavior ebbed and the animals became much more responsive to social cues such as gender...the initial genetic predisposition apparently gets masked by reproductive maturity.
Their work suggests that genetic influences on juvenile social behavior may be quite distinct from genetic factors that affect adult social behavior, a finding the potentially useful for understanding social evolution, as well as developing more realistic animal models of pervasive developmental disorders, such as autism.

Just a nap will do it.....

It doesn't take overnight, Nishida and Walker show that just taking a nap boosts memory consolidation.

Two groups of subjects trained on a motor-skill task using their left hand – a paradigm known to result in overnight plastic changes in the contralateral, right motor cortex. Both groups trained in the morning and were tested 8 hr later, with one group obtaining a 60–90 minute intervening midday nap, while the other group remained awake. At testing, subjects that did not nap showed no significant performance improvement, yet those that did nap expressed a highly significant consolidation enhancement. Within the nap group, the amount of offline improvement showed a significant correlation with the global measure of stage-2 NREM sleep. However, topographical sleep spindle analysis revealed more precise correlations. Specifically, when spindle activity at the central electrode of the non-learning hemisphere (left) was subtracted from that in the learning hemisphere (right), representing the homeostatic difference following learning, strong positive relationships with offline memory improvement emerged–correlations that were not evident for either hemisphere alone.
(Note: sleep spindles are a defining electrophysiological signature of NREM sleep involving short (~1 ) synchronous burst of activity (12–15 Hz) that may represent triggers of synaptic potentiation leading to neural plasticity.)

Legend (click to enlarge figure): Spindle density and offline (nap) memory enhancement. a, Correlations between offline motor memory enhancement and spindle density in the non-learning hemisphere (electrode site C3) and learning hemisphere (electrode site C4) individually. b, Correlations between offline motor memory improvement and the subtracted difference in spindle density between the learning hemisphere versus the non-learning hemisphere (C4–C3).

Pain Mechanisms

Nature Magazine offers a nice free summary poster on pain mechanisms.

Friday, April 13, 2007

Framing Science

I give you in its entirety an essay by Nisbet and Mooney in a recent issue of Science Magazine (Vol. 316. no. 5821, p. 56):

Issues at the intersection of science and politics, such as climate change, evolution, and embryonic stem cell research, receive considerable public attention, which is likely to grow, especially in the United States as the 2008 presidential election heats up. Without misrepresenting scientific information on highly contested issues, scientists must learn to actively "frame" information to make it relevant to different audiences. Some in the scientific community have been receptive to this message (1). However, many scientists retain the well-intentioned belief that, if laypeople better understood technical complexities from news coverage, their viewpoints would be more like scientists', and controversy would subside.

In reality, citizens do not use the news media as scientists assume. Research shows that people are rarely well enough informed or motivated to weigh competing ideas and arguments. Faced with a daily torrent of news, citizens use their value predispositions (such as political or religious beliefs) as perceptual screens, selecting news outlets and Web sites whose outlooks match their own (2). Such screening reduces the choices of what to pay attention to and accept as valid (3).

Frames organize central ideas, defining a controversy to resonate with core values and assumptions. Frames pare down complex issues by giving some aspects greater emphasis. They allow citizens to rapidly identify why an issue matters, who might be responsible, and what should be done (4, 5).

Consider global climate change. With its successive assessment reports summarizing the scientific literature, the United Nations' Intergovernmental Panel on Climate Change has steadily increased its confidence that human-induced greenhouse gas emissions are causing global warming. So if science alone drove public responses, we would expect increasing public confidence in the validity of the science, and decreasing political gridlock.

Despite recent media attention, however, many surveys show major partisan differences on the issue. A Pew survey conducted in January found that 23% of college-educated Republicans think global warming is attributable to human activity, compared with 75% of Democrats (6). Regardless of party affiliation, most Americans rank global warming as less important than over a dozen other issues (6). Much of this reflects the efforts of political operatives and some Republican leaders who have emphasized the frames of either "scientific uncertainty" or "unfair economic burden" (7). In a counter-strategy, environmentalists and some Democratic leaders have framed global warming as a "Pandora's box" of catastrophe; this and news images of polar bears on shrinking ice floes and hurricane devastation have evoked charges of "alarmism" and further battles.

Recently, a coalition of Evangelical leaders have adopted a different strategy, framing the problem of climate change as a matter of religious morality. The business pages tout the economic opportunities from developing innovative technologies for climate change. Complaints about the Bush Administration's interference with communication of climate science have led to a "public accountability" frame that has helped move the issue away from uncertainty to political wrongdoing.

As another example, the scientific theory of evolution has been accepted within the research community for decades. Yet as a debate over "intelligent design" was launched, antievolutionists promoted "scientific uncertainty" and "teach-the-controversy" frames, which scientists countered with science-intensive responses. However, much of the public likely tunes out these technical messages. Instead, frames of "public accountability" that focus on the misuse of tax dollars, "economic development" that highlight the negative repercussions for communities embroiled in evolution battles, and "social progress" that define evolution as a building block for medical advances, are likely to engage broader support.

The evolution issue also highlights another point: Messages must be positive and respect diversity. As the film Flock of Dodos painfully demonstrates, many scientists not only fail to think strategically about how to communicate on evolution, but belittle and insult others' religious beliefs (8).

On the embryonic stem cell issue, by comparison, patient advocates have delivered a focused message to the public, using "social progress" and "economic competitiveness" frames to argue that the research offers hope for millions of Americans. These messages have helped to drive up public support for funding between 2001 and 2005 (9, 10). However, opponents of increased government funding continue to frame the debate around the moral implications of research, arguing that scientists are "playing God" and destroying human life. Ideology and religion can screen out even dominant positive narratives about science, and reaching some segments of the public will remain a challenge (11).

Some readers may consider our proposals too Orwellian, preferring to safely stick to the facts. Yet scientists must realize that facts will be repeatedly misapplied and twisted in direct proportion to their relevance to the political debate and decision-making. In short, as unnatural as it might feel, in many cases, scientists should strategically avoid emphasizing the technical details of science when trying to defend it.

References

1. T. M. Beardsley, Bioscience 56, 7 (2006). www.aibs.org/bioscience-editorials/editorial_2006_07.html.
2. S. L. Popkin, The Reasoning Voter (Univ. of Chicago Press, Chicago, IL, 1991).
3. J. Zaller, Nature and Origins of Mass Opinion (Cambridge Univ. Press, New York, 1992).
4. W. A. Gamson, A. Modigliani, Am. J. Sociol. 95, 1 (1989).
5. V. Price, et al., Public Opin. Q. 69, 179 (2005).
6. Pew Center for the People and the Press (2007); http://pewresearch.org/pubs/282/global-warming-a-divide-on-causes-and-solutions.
7. A. M. McCright, R. E. Dunlap, Soc. Probl. 50, 3 (2003).
8. Film promotion, www.flockofdodos.com/
9. Virginia Commonwealth University Life Sciences Survey (2006); www.vcu.edu/lifesci/images2/ls_survey_2006_report.pdf
10. Pew Center for the People and the Press (2006); http://peoplepress.org/reports/display.php3?ReportID=283.
11. M. C. Nisbet, Int. J. Public Opin. Res. 17 (1), 90 (2005).

Relationships in an e-society: small versus large groups

From the editor's summary of an article in Nature by Palla et al. (PDF here):

The dynamics of social groups as they interact electronically is central to how modern society operates. A study of patterns of information exchange between two groups of individuals — collaborating scientists and cell phone users — has been used to devise an algorithm that relates information exchange to group stability. The data show that small groups have a few strong relationships at their core. And as long as these persist, the clique remains. But for large communities, continuous change is the key to stability. These findings offer a new view on the fundamental differences between the dynamics of small groups and large institutions.

Palla et al.'s abstract:
The rich set of interactions between individuals in society results in complex community structure, capturing highly connected circles of friends, families or professional cliques in a social network. Thanks to frequent changes in the activity and communication patterns of individuals, the associated social and communication network is subject to constant evolution. Our knowledge of the mechanisms governing the underlying community dynamics is limited, but is essential for a deeper understanding of the development and self-optimization of society as a whole. We have developed an algorithm based on clique percolation that allows us to investigate the time dependence of overlapping communities on a large scale, and thus uncover basic relationships characterizing community evolution. Our focus is on networks capturing the collaboration between scientists and the calls between mobile phone users. We find that large groups persist for longer if they are capable of dynamically altering their membership, suggesting that an ability to change the group composition results in better adaptability. The behaviour of small groups displays the opposite tendency—the condition for stability is that their composition remains unchanged. We also show that knowledge of the time commitment of members to a given community can be used for estimating the community's lifetime. These findings offer insight into the fundamental differences between the dynamics of small groups and large institutions.

Thursday, April 12, 2007

How pretty faces sell boring products - conditioning our brain's reward system

Bray and O'Doherty's report in the Journal of Neurophysiology illustrates the biology behind the selling power of beautiful models in advertisements for mundane products, and should be of interest to neuro-marketers everywhere. PDF here. Their abstract:

Attractive faces can be considered to be a form of visual reward. Previous imaging studies have reported activity in reward structures including orbitofrontal cortex and nucleus accumbens during presentation of attractive faces. Given that these stimuli appear to act as rewards, we set out to explore whether it was possible to establish conditioning in human subjects by pairing presentation of arbitrary affectively neutral stimuli with subsequent presentation of attractive and unattractive faces. Furthermore, we scanned human subjects with functional magnetic resonance imaging (fMRI) while they underwent this conditioning procedure to determine whether a reward-prediction error signal is engaged during learning with attractive faces as is known to be the case for learning with other types of reward such as juice and money. Subjects showed changes in behavioral ratings to the conditioned stimuli (CS) when comparing post- to preconditioning evaluations, notably for those CSs paired with attractive female faces. We used a simple Rescorla-Wagner learning model to generate a reward-prediction error signal and entered this into a regression analysis with the fMRI data. We found significant prediction error-related activity in the ventral striatum during conditioning with attractive compared with unattractive faces. These findings suggest that an arbitrary stimulus can acquire conditioned value by being paired with pleasant visual stimuli just as with other types of reward such as money or juice. This learning process elicits a reward-prediction error signal in a main target structure of dopamine neurons: the ventral striatum. The findings we describe here may provide insights into the neural mechanisms tapped into by advertisers seeking to influence behavioral preferences by repeatedly exposing consumers to simple associations between products and rewarding visual stimuli such as pretty faces.

Legend - Prediction error related activity in the nucleus accumbens. A: voxels in the nucleus accumbens were significantly activated in a contrast of prediction error signals for attractive faces vs. unattractive faces, voxels in yellow are significant at P <>

MindBlog back in Madison, Wisconsin


Turns out I got back just in time for what is hopefully the last snowstorm of the winter. This reminds me why I was in Ft. Lauderdale for the past five months.....

Wednesday, April 11, 2007

"Nest" cells in the mouse brain. Category knowledge shown.

An interesting article in PNAS from Lin et al. (PDF here). Their abstract:

As important as memory is to our daily functions, the ability to extract fundamental features and commonalities from various episodic experiences and to then generalize them into abstract concepts is even more crucial for both humans and animals to adapt to novel and complex situations. Here, we report the neural correlates of the abstract concept of nests or beds in mice. Specifically, we find hippocampal neurons that selectively fire or cease to fire when the mouse perceives nests or beds, regardless of their locations and environments. Parametric analyses show that responses of nest cells remain invariant over changes in the nests' physical shape, style, color, odor, or construction materials; rather, their responses are driven by conscious awareness and physical determination of the categorical features that would functionally define nests. Such functionality-based abstraction and generalization of conceptual knowledge, emerging from episodic experiences, suggests that the hippocampus is an intrinsic part of the hierarchical structure for generating concepts and knowledge in the brain.
Here is one figure and one movie from the paper:

Legend - Invariant responses over the geometric shapes, physical appearances, colors, construction materials, etc. (A) Invariant responses of Cell #1 to the geometric shapes of nests. As shown by both the perievent spike rasters and perievent spike histograms, Cell #1 exhibited a significant firing increase in response to a new circular nest made out of the top part of a cardboard coffee cup with a wall height of 2.5 cm and a diameter of 7.5 cm (Left), a square cardboard nest (Center), and a triangular cardboard nest (Right). (B) Invariant responses of Cell #1 to nests made from different materials. A metal nest (Left), plastic nest (Center), and porcelain nest (Right) were tested. (C) The cell also increased its firing when the mouse encountered natural cotton nests (Left and Center) but not to five cotton balls that were simply lumped together (Right). The bin width in the perievent spike histogram is 250 ms.


Click to download Movie 1. Description of movie: "Transient-on" type of nest cell responses and its functionality-based encoding of conceptual knowledge of nests. The first movie segment shows that Cell #1 of mouse-A exhibited "transient-on"-type responses to the home nest but not to another similarly shaped, smaller circular object (water cup). The second movie segment shows that Cell #1 did not respond to the plastic nest that was placed in an inverted manner (so that it would function as a small stage). However, once the plastic nest reverted back to its normal nest position, the cell exhibited robust firing up to 40 Hz. Because it is the same object and placed at the same location, this inversion experiment demonstrates that the nest cell encodes the functionality of the nest rather than merely physical appearances, materials, or spatial location, etc.

Why the rich behave badly... "disinhibition"

Richard Conniff writes an OpEd piece in the 4/4/07 NY Times (PDF here) pointing out the work of UC Berkely psychologist Dacher Keltner and others who study the effect of power on social perception and behavior. Their work suggests that elevated power leads to behavioral disinhibition and reduced vigilance. They find that ideological partisans with power construe their dispute in more stereotypical, polarized fashion, that elevated social status leads to disinhibited social behavior, and that power, whether derived from group status or experimental manipulation, relates to the experience of increased positive emotion and reduced negative emotion.

In what Conniff calls the "Cookie Monster Experiment" (a much milder version of the Stanford Prison Experiment) Keltner:

...took groups of three ordinary volunteers and randomly put one of them in charge. Each trio had a half-hour to work through a boring social survey. Then a researcher came in and left a plateful of precisely five cookies. Care to guess which volunteer typically grabbed an extra cookie? The volunteer who had randomly been assigned the power role was also more likely to eat it with his mouth open, spew crumbs on partners and get cookie detritus on his face and on the table.

It reminded the researchers of powerful people they had known in real life. One of them, for instance, had attended meetings with a magazine mogul who ate raw onions and slugged vodka from the bottle, but failed to share these amuse-bouches with his guests. Another had been through an oral exam for his doctorate at which one faculty member not only picked his ear wax, but held it up to dandle lovingly in the light.
Keltner theorizes:
...that getting power causes people to focus so keenly on the potential rewards, like money, sex, public acclaim or an extra chocolate-chip cookie — not necessarily in that order, or frankly, any order at all, but preferably all at once — that they become oblivious to the people around them.

Indeed, the people around them may abet this process, since they are often subordinates intent on keeping the boss happy. So for the boss, it starts to look like a world in which the traffic lights are always green (and damn the pedestrians). Professor Keltner and his fellow researchers describe it as an instance of “approach/inhibition theory” in action: As power increases, it fires up the behavioral approach system and shuts down behavioral inhibition.

Tuesday, April 10, 2007

Rapid memory consolidation shown...

Memory encoding occurs rapidly, and requires the hippocampus, but the consolidation of memory in the neocortex has long been held to be a more gradual process. Tse et al now show in experiments with rats learning the position of new treats placed in a maze:

...that systems consolidation can occur extremely quickly if an associative "schema" into which new information is incorporated has previously been created. In experiments using a hippocampal-dependent paired-associate task for rats, the memory of flavor-place associations became persistent over time as a putative neocortical schema gradually developed. New traces, trained for only one trial, then became assimilated and rapidly hippocampal-independent. Schemas also played a causal role in the creation of lasting associative memory representations during one-trial learning. The concept of neocortical schemas may unite psychological accounts of knowledge structures with neurobiological theories of systems memory consolidation. (PDF here)
And, from Larry Squire's perspective article on this paper (PDF here):
Legend. (click on figure to enlarge) When a rat learns associations between flavors and spatial locations, as studied by Tse et al. (1), the associations are initially learned as individual facts (left). With extended training, the animal develops an organized structure or schema for flavors and places (middle). This organized knowledge structure (bold lines) can then support rapid learning of new associations in a single trial and the rapid consolidation of information into the neocortex (right).

Do animals experience past and future?

Carl Zimmer writes a nice piece in the 4/3 NYTimes on "Time in the Animal Mind" (PDF HERE).

Legend: Scrub jays, left, seem able to plan for the future in experiments, hiding today’s pine nuts for tomorrow’s breakfast. Squirrel monkeys also seem to think about future consequences, while hummingbirds seem to recall time and location of visits to flowers, and rats to remember where they encountered food in a maze. (Credits: from left, Adam Jones/Photo Researchers; Luke MacGregor/Reuters; Esteban Felix/Associated Press; Will & Deni McIntyre/Photo Researchers)

The animals shown in the figure have been shown to have impressive powers of memory, but this doesn't have to imply having a sense of memory or self, i.e. 'thinking about' past or future.

Some argue that mental time travel is distinctive to hominids. Humans can remember events long past and envision the future, and recent experiments by Schacter's lab at Harvard have shown that brain areas involved in episodic memory become active also when people think of themselves in the future.

What about animal's sense of the future? Can they plan ahead? Nicola, Univ. of Cambridge, has done interesting experiments showing sophisticated memory in scrub jays, and she

"recently tested her scrub jays for foresight. She and her colleagues put the birds in three adjoining compartments for six days. Each morning the birds were shut for two hours in one of two rooms. In one room they got nothing to eat. In the other room, they got powdered pine nuts (the scrub jays can eat the powder, but they cannot cache it). For the rest of the day, each bird could move around all three rooms and enjoy more powdered nuts.

On the seventh day, the scientists switched the powdered pine nuts with real ones. If the birds were so inclined, they could cache the pine nuts in ice cube trays the scientists put in the two morning rooms. “If I’m a bird, what I could do is take some of the provisions and hide it in there so that if I do wake up there in the morning, I can get my own breakfast,” Dr. Clayton said.

Dr. Clayton found that the birds put over three times more pine nuts in the no-breakfast room than in the breakfast room. She argues that the results mean that birds can take action for their future needs, knowing what they’ll need and where they’ll need it."
This and similar experiments in other animals may over the next few years provide more compelling evidence that animals do plan ahead, and thus take away yet another feature that many have thought distinctive to humans.

Monday, April 09, 2007

Body Ritual among the Nacirema

This is a hoot!

Savant Autism - part 1

I thought this two part sequence on autism was worth passing on....

Savant Autism - part 2

Friday, April 06, 2007

MindBlog leaves 'paradise'

Postings may become erratic or non-existent for several days as I leave my snowbird site, Fort Lauderdale, and drive back to Madison Wisconsin on Monday, April 9.

This is what I leave behind: The beach and the condo:

Motor cortex for the hand and numerical counting

The April 2007 issue of the Journal of Cognitive Neuroscience has interesting articles on this topic by Andres et al. and Sato et al. Their abstracts:

Andres et al.

The finding that number processing activates a cortical network partly overlapping that recruited for hand movements has renewed interest in the relationship between number and finger representations. Further evidence about a possible link between fingers and numbers comes from developmental studies showing that finger movements play a crucial role in learning counting. However, increased activity in hand motor circuits during counting may unveil unspecific processes, such as shifting attention, reciting number names, or matching items with a number name. To address this issue, we used transcranial magnetic stimulation to measure changes in corticospinal (CS) excitability during a counting task performed silently and using either numbers or letters of the alphabet to enumerate items. We found an increased CS excitability of hand muscles during the counting task, irrespective of the use of numbers or letters, whereas it was unchanged in arm and foot muscles. Control tasks allowed us to rule out a possible influence of attention allocation or covert speech on CS excitability increase of hand muscles during counting. The present results support a specific involvement of hand motor circuits in counting because no CS changes were found in arm and foot muscles during the same task. However, the contribution of hand motor areas is not exclusively related to number processing because an increase in CS excitability was also found when letters were used to enumerate items. This finding suggests that hand motor circuits are involved whenever items have to be put in correspondence with the elements of any ordered series.

Sato et al.
Developmental and cross-cultural studies show that finger counting represents one of the basic number learning strategies. However, despite the ubiquity of such an embodied strategy, the issue of whether there is a neural link between numbers and fingers in adult, literate individuals remains debated. Here, we used transcranial magnetic stimulation to study changes of excitability of hand muscles of individuals performing a visual parity judgment task, a task not requiring counting, on Arabic numerals from 1 to 9. Although no modulation was observed for the left hand muscles, an increase in amplitude of motor-evoked potentials was found for the right hand muscles. This increase was specific for smaller numbers (1 to 4) as compared to larger numbers (6 to 9). These findings indicate a close relationship between hand/finger and numerical representations.

Creation Science

Thursday, April 05, 2007

Most popular consciousness papers for March

Again I pass on the list of articles downloaded most frequently from the ASSC Eprints Archive

The "five most popular papers" are:

1. Windt, Jennifer Michelle and Metzinger, Thomas (2006) *The philosophy of
dreaming and self-consciousness: What happens to the experiential subject
during the dream state?* In: The new science of dreaming. Praeger
Imprint/Greenwood Publishers, Estport, CT. With 1488 downloads from 23
countries. See:http://eprints.assc.caltech.edu/200/

2. Sagiv, Noam and Ward, Jamie (2006) *Crossmodal interactions: lessons from
synesthesia.* In: Visual Perception, Part 2 - Fundamentals of Awareness:
Multi-Sensory Integration and High-Order Perception. Progress in Brain
Research, Volume 155. Elsevier, pp. 259-271. ISBN 0444519270. With 1034
downloads from 17 countries. See: http://eprints.assc.caltech.edu/224/

3. Carruthers, Peter (2007) *The illusion of conscious will.* In: Synthese,
96. With 879 downloads from 19 countries. See: http://eprints . assc
.caltech.edu/213/

4. Robbins, Stephen E (2006) *Bergson and the holographic theory of
mind.* Phenomenology
and the Cognitive Sciences, 5. pp. 365-394. With 760 downloads from 16
countries. See:http://eprints.assc.caltech.edu/206/

5. Chai-Youn, Kim and Blake, Randolph (2005) *Psychophysical magic:
rendering the visible 'invisible'.* Trends in Cognitive Science, 9 (8).
pp. 381-8. With 729 downloads from 15 countries. See:
http://eprints.assc.caltech.edu/30/.

Self and social cognition in the brain

Uddin et al. speculate in Trends in Cognitive Science (Volume 11, Issue 4 , April 2007, Pages 153-157) about the respective roles of cortical midline structures (CMS) and frontoparietal mirror neurons (MNS) in evaluation of self and others. Below I relay one of their summary paragraphs, and the PDF which contains images of relevant brain regions can be obtained HERE.

It has recently been proposed that internally oriented processes that focus on one's own or others’ mental states rely on cortical midline structures, whereas externally focused processes based on one's own or others’ visible features and actions rely on lateral frontoparietal networks. We suggest here a similar distinction, which might further reconcile disparate findings with regard to the various proposed functions of cortical midline structures, while incorporating what is known about the role of the human mirror-neuron system in social cognition. Whereas there is mounting evidence that the right frontoparietal system is involved in representing the physical, embodied self (in addition to its role in understanding the actions of others), the cortical midline structures that comprise the default-mode network seem to be more involved in maintaining a self-representation in evaluative terms, which requires self-referential processing and understanding of others’ mental states. We speculate that the CMS might support evaluative simulation in the same way that the MNS supports motor simulation. This distinction serves as a practical division of labor between two networks that are specialized for two related processes that are crucial to navigating the social world. The mirror-neuron system provides the essential physical other-to-self mapping that is necessary for comprehending physical actions of intentional agents, whereas cortical midline structures maintain and support processes that are related to understanding complex psychological aspects of others, such as attitudes, perhaps by simulation of one's own attitudes.

Wednesday, April 04, 2007

Emotion and consciousness - a Review

Tsuchiya and Adolphs at Cal. Tech. offer a broad review of this topic in Trends in Cognitive Sciences (Volume 11, Issue 4, April 2007, Pages 158-167) which has some excellent illustrations for teaching. Here I show the abstract and three figures from the article, the PDF is HERE.

Figure 2. (click to enlarge) Brain regions that are important for emotion state (blue), feeling of emotion (red) and level of consciousness (green). Other components of an emotion state, and the content of consciousness, are presumed to rely on more variable and distributed structures that would depend on the particular kind of emotion or conscious experience and, therefore, are not depicted here. (a) Sagittal view shows that the hypothalamus, amygdala, brainstem nuclei, including periaquedactal gray and parabrachial nuclei, orbitofrontal cortex and anterior cingulate cortex are important for the expression of emotion (blue). Anterior and posterior cingulate, including precuneus, and orbitofrontal cortex are important for the experience of emotion (red). Intralaminar thalamus and the ascending reticular formation are necessary for the maintenance of arousal and wakefulness – that is, the level (state) of consciousness 8 and 12. The intralaminar thalamic nucleus is a diffuse structure, enlarged here for illustration purposes. (b) Coronal slice at the level of the white line in (a). The thalamus, hypothalamus and amygdala are shown again. Insular cortex (red) is an important structure for the experience of emotion [also shown in (d)]. (c) Bilateral prefrontal and parietal cortices are broadly important for the level of consciousness (green) [36]. The figure omits other important central nervous system components of emotion, such as the rostral ventrolateral medulla (important for control of autonomic function) and components of the spinal cord itself, all of which contribute to substantial processing that is related to interoceptive and homeostatic information [46], and also parts of the nucleus accumbens and ventral pallidum that participate in reward and positive affect 4 and 60 (See also Figure 3c). (d) The surface of the prefrontal cortex has been removed to reveal the insular cortex (red). Human brain images are adapted, with permission, from the Digital Anatomist Project at the University of Washington (http://www9.biostr.washington.edu/da.html).


Figure 3. (click to enlarge) Shared neural substrates for emotion and consciousness. (a) Data from functional imaging show that a frontoparietal network is compromised in coma, vegetative states, sleep and under anesthesia (black regions; but also see green regions in Figure 2). Abbreviations: F, prefrontal; MF, mesiofrontal; P, posterior parietal; Pr, posterior cingulate/precuneus. (a) reproduced, with permission, from Ref. [8]. (b) In a quiet but awake resting state, there are two distinct networks of structures in the human brain that are either correlated (color-coded red to orange) or anti-correlated (blue to green) with the parietal cortex, indicated by the arrow. The blue–green network of structures might be particularly important for reflective and interoceptive processing and crucial to the level of consciousness and feeling emotions. (b) reproduced, with permission, from Ref. [14]. (c) Anatomical structures that are important for feelings (emotion experience) involve homeostatic loops. A main circuit for efferent autonomic control arises from distributed cortical sectors in anterior and subgenual cingulate cortex, medial orbital cortex and insula, as well as from amygdala. These structures in turn project to paraventricular hypothalamus and periaqueductal gray (PAG) matter, from there to integrative centers in the medulla (RVLM, rostral ventrolateral medulla; VMM, ventromedial medulla) and the spinal cord, and then out to effector organs. Afferent autonomic processing occurs in part through dedicated sensory channels and involves brainstem nuclei, including the parabrachial nucleus (PB), the hypothalamus, thalamus (VM, ventromedial nucleus), and then again the same set of cortical regions. With the exception of the thalamus, there are homeostatic control loops at multiple levels, involving all structures in both afference and efference. Many of these structures are activated in a variety of experiments that involve emotion experiences 16, 17 and 46, making them promising candidates for the neural correlates of emotion experience 3 and 46. It has been proposed that primates possess a unique mapping of autonomic interoceptive information within the insular cortex that forms the substrate of conscious feelings [46]. The afferent limb is shown in the top row and the efferent limb in the bottom row; please note that only a subset of the connectivity is depicted in this figure for clarity. The red lines indicate pathways in primates thought to be more phylogenetically recent that provide a direct thalamocortical input, reflecting the physiological condition of the body. Abbreviations: A1, catecholaminergic cell groups A1; ACC, anterior cingulate; MD, medial dorsal nucleus; NTS, nucleus of the solitary tract. (c) modified, with permission, from Ref. [72].

Figure 4. (click to enlarge) Microgenesis of emotional processing. Emotional responses span a large temporal range (from 100 ms or less, to minutes). (a) Responses to emotional visual stimuli can occur rapidly in prefrontal cortex [50] or amygdala, in part mediated by subcortical inputs. Emotional response in the amygdala also influences early visual processing [51] and is modulated by volitional self-regulation 47 and 52. (b) At later time slices (100–200 ms), sensory cortices provide more detailed input to emotion-inducing structures like the amygdala. Two components that are important to face processing are shown: the superior temporal cortex (green), important for encoding dynamic information such as facial expression, and the fusiform gyrus (blue), important for encoding static information such as identity. (c) Once the emotional meaning of a stimulus has been evaluated by the brain, emotional responses are triggered in the body via projections from amygdala and medial prefrontal cortex to brainstem nuclei and hypothalamus (not shown), and are in turn represented in structures such as the insula. This figure emphasizes that what we refer to as an ‘emotion state’ throughout this article is in fact a complex set of processes that unfold at various points in time. Color key: black, primary visual cortex; blue, fusiform gyrus; green, superior temporal cortex; purple, insula; faint red, orbitofrontal cortex; solid red, amygdala; yellow, superior colliculus. Reproduced, with permission, from Ref. [73].

Rhythms linking episodic and procedural memory systems.

I pass on this abstract from an interesting paper by DeCoteau et al. PDF is HERE.

The striatum and hippocampus are conventionally viewed as complementary learning and memory systems, with the hippocampus specialized for fact-based episodic memory and the striatum for procedural learning and memory. Here we directly tested whether these two systems exhibit independent or coordinated activity patterns during procedural learning. We trained rats on a conditional T-maze task requiring navigational and cue-based associative learning. We recorded local field potential (LFP) activity with tetrodes chronically implanted in the caudoputamen and the CA1 field of the dorsal hippocampus during 6–25 days of training. We show that simultaneously recorded striatal and hippocampal theta rhythms are modulated differently as the rats learned to perform the T-maze task but nevertheless become highly coherent during the choice period of the maze runs in rats that successfully learned the task. Moreover, in the rats that acquired the task, the phase of the striatal–hippocampal theta coherence was modified toward a consistent antiphase relationship, and these changes occurred in proportion to the levels of learning achieved. We suggest that rhythmic oscillations, including theta-band activity, could influence not only neural processing in cortico-basal ganglia circuits but also dynamic interactions between basal ganglia-based and hippocampus-based forebrain circuits during the acquisition and performance of learned behaviors. Experience-dependent changes in coordination of oscillatory activity across brain structures thus may parallel the well known plasticity of spike activity that occurs as a function of experience.

Tuesday, April 03, 2007

Exercise increases nerve cell growth in brain area crucial to cognitive aging.

Pereira et al. have used an interesting approach to demonstrate that exercise causes the growth of new nerve cells in the dentate gyrus (part of the hippocampus) of mice and humans. Because new nerve cell formation usually is accompanied by synthesis of new blood vessels and increased blood flow, they used MRI measurement of cerebral blood volume as an assay of new nerve cell formation in the living brain. Here is their abstract, and a figure from the paper. The PDF of the paper can be downloaded HERE.

With continued debate over the functional significance of adult neurogenesis, identifying an in vivo correlate of neurogenesis has become an important goal. Here we rely on the coupling between neurogenesis and angiogenesis and test whether MRI measurements of cerebral blood volume (CBV) provide an imaging correlate of neurogenesis. First, we used an MRI approach to generate CBV maps over time in the hippocampal formation of exercising mice. Among all hippocampal subregions, exercise was found to have a primary effect on dentate gyrus CBV, the only subregion that supports adult neurogenesis. Moreover, exercise-induced increases in dentate gyrus CBV were found to correlate with postmortem measurements of neurogenesis. Second, using similar MRI technologies, we generated CBV maps over time in the hippocampal formation of exercising humans. As in mice, exercise was found to have a primary effect on dentate gyrus CBV, and the CBV changes were found to selectively correlate with cardiopulmonary and cognitive function. Taken together, these findings show that dentate gyrus CBV provides an imaging correlate of exercise-induced neurogenesis and that exercise differentially targets the dentate gyrus, a hippocampal subregion important for memory and implicated in cognitive aging.

Legend - (click on figure to enlarge) Exercise selectively increases dentate gyrus CBV in humans. (a) Exercise had a selective effect on dentate gyrus CBV. Bar graph shows the mean relative CBV (rCBV) values for each hippocampal subregion before exercise (open bars) and after exercise (filled bars). As in mice, the dentate gyrus was the only hippocampal subregion that showed a significant exercise effect, whereas the entorhinal cortex showed a nonsignificant increase in CBV. (b) An individual example. (Left) High-resolution MRI slice that visualizes the external morphology and internal architecture of the hippocampal formation. (Center) Parcellation of the hippocampal subregions (green, entorhinal cortex; red, dentate gyrus; blue, CA1 subfield; yellow, subiculum). (Right) Hippocampal CBV map (warmer colors reflect higher CBV).

Mirror Neurons - gee whiz popular video

A engaging and easy to watch popularized version of material I've written about earlier (see 1/20/07; 12/19/06; and my lecture 10/27/06)).

Monday, April 02, 2007

Social exclusion causes an empathy block.

From the Editor's choice section of the March 23 issue of Science Magazine, a discussion of Twenge et al., in the Journal of Personality & Social Psychology. 92(1):56-66, January 2007:

Everyday experience confirms the general belief that humans are social animals; the neural pathways subserving prosocial behaviors are a subject of current research, and the evolutionary origins of these behaviors are hotly debated. Although there is evidence that social exclusion can elicit redoubled efforts to develop social connections, the consequences of exclusion are predominantly negative--feeling hurt, acting belligerently, or adopting a lone-wolf lifestyle--and Twenge et al. have begun to examine what might mediate these apparently atypical responses.

Using a variety of experimental contexts (such as the canonical spilled-pencils incident) and measures (such as donations of money or cooperation in a prisoner's dilemma game), they find that being characterized as having a high likelihood of a prosocial lifestyle with many strong relationships, such as marriage, resulted in participants helping to pick up pencils (on average, 8 out of 20 spilled) versus the performance of those labeled as being apt to lead solitary lives (less than 1 pencil picked up). As to what factors mediate the extent (or absence) of prosocial behavior, some of the likely candidates (trusting the other or having a sense of belonging) did not register, whereas empathic concern did. Combining this finding with an earlier one, which showed that social exclusion activates the neural circuits encoding pain, produces the speculation that an after-effect of rejection is an emotional numbness or an inability to mirror the affective states of others.
Here is the Twenge et al. abstract, the PDF can be downloaded HERE.
In 7 experiments, the authors manipulated social exclusion by telling people that they would end up alone later in life or that other participants had rejected them. Social exclusion caused a substantial reduction in prosocial behavior. Socially excluded people donated less money to a student fund, were unwilling to volunteer for further lab experiments, were less helpful after a mishap, and cooperated less in a mixed-motive game with another student. The results did not vary by cost to the self or by recipient of the help, and results remained significant when the experimenter was unaware of condition. The effect was mediated by feelings of empathy for another person but was not mediated by mood, state self-esteem, belongingness, trust, control, or self-awareness. The implication is that rejection temporarily interferes with emotional responses, thereby impairing the capacity for empathic understanding of others, and as a result, any inclination to help or cooperate with them is undermined.

Neurite Outgrowth

I've always been fascinated by time lapse videos of neurons growing on the surface of a culture dish. Here is one example:

The Male-Warrior Hypothesis

Some clips from Van Vugt et al:

Evolutionary scientists argue that human cooperation is the product of a long history of competition among rival groups. There are various reasons to believe that this logic applies particularly to men. In three experiments, using a step-level public-goods task, we found that men contributed more to their group if their group was competing with other groups than if there was no intergroup competition. Female cooperation was relatively unaffected by intergroup competition. These findings suggest that men respond more strongly than women to intergroup threats. ..These findings fit nicely with an evolutionary hypothesis about specific male intergroup adaptations—the male-warrior hypothesis—and such evolved intergroup traits are likely to be reinforced through cultural processes, for example, during childhood socialization...Women's social psychology is likely to be shaped more strongly by different kinds of needs, such as defending their offspring and creating supportive social networks
The article's PDF can be downloaded HERE.