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.

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.

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.

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.

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).

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.

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.

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.

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.

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).