Monday, June 30, 2008

MindBlog on the road

This week, I'm starting a seven day vacation in Toronto with my partner Len. It is our 19th anniversary. The mindblog posts that appear will be using Blogger's neat new feature that permits the specification of a date in the future for a prepared posting to actually appear on the website.

Yesterday, Sunday, June 29, we hosted a social/musical at our home on Twin Valley road in the Town of Middleton, Wisconsin. Len does the food and I do the music. Over the next period of time, I will post here and on YouTube the music we played. Here is the invitation to the event, followed by a photo taken just before the music, and one during it:

Please join Deric and Len at the Twin Valley schoolhouse sunday afternoon, June 29, from 3 to 6 p.m. for conversation, wine, and Len's appetizers & h'orderves. If you like, bring a wine or other liquid to share.

Music at 4:00 p.m. (~45 min duration)
Two tangoes by Astor Piazzolla
Four movements from the two Mendelssohn piano trios.

Deric (piano), Daphne Tsao (violin) and Sonny Enslen (Cello)

Young and old brains differ in encoding positive information

A number of studies have revealed a "positivity shift" with aging; whereas young adults are more likely to remember negative information than positive or neutral information, older adults may be at least as likely (or even more likely) to remember positive information compared with negative information. It has been proposed that this "positivity shift" may occur because older adults put more emphasis on emotion regulation goals than do young adults, with older adults having a greater motivation to derive emotional meaning from life and to maintain positive affect. In the service of these goals, older adults may focus their attention on things that will elicit pleasant feelings and may process positive information in a more self-referential fashion. Thus this work (slightly edited) from Kensinger and Schacter probing the issue is of interest:
Young and older adults are more likely to remember emotional information than neutral information. The authors performed a magnetic resonance imaging study examining the neural processes supporting young (ages 18–35) and older (ages 62–79) adults' successful encoding of positive, negative, and neutral objects (e.g., a sundae, a grenade, a canoe). The results revealed general preservation of the emotional memory network across the age groups. Both groups recruited the amygdala and the orbito-frontal cortex during the successful encoding of positive and negative information. Both ages also showed valence-specific recruitment: right fusiform activity was greatest during the successful encoding of negative information, whereas left prefrontal and temporal activity was greatest during the successful encoding of positive information. These valence-specific processes are consistent with behavioral evidence that negative information is processed with perceptual detail, whereas positive information is processed at a conceptual or schematic level. The only age differences in emotional memory emerged during the successful encoding of positive items: Older adults showed more activity in the medial prefrontal cortex and along the cingulate gyrus than young adults. Because these regions often are associated with self-referential processing, these results suggest that older adults' mnemonic boost for positive information may stem from an increased tendency to process this information in relation to themselves.

Figure - Regions that showed a stronger correspondence to subsequent general recognition (i.e., subsequently recognized > subsequently forgotten) for the positive items than for the neutral or negative items. Red regions showed this correspondence for both young and older adults. Green regions showed this correspondence for the older adults but not for the young adults. No regions showed this correspondence for the young adults but not the older adults, consistent with the behavioral finding that only older adults showed mnemonic enhancement for the positive items.

Friday, June 27, 2008

ScienceHack - monkey brain moving robotic arm

I stumbled across this site with interesting science videos from a number of areas (biology, psychology, robotics, etc.). They are mainly at a superficial 'gee whiz' level, but quite engaging. Here is the Monkey moving a robotic arm. This is work from the Pittsburgh group, described in Nature, which promises to lead to effective therapy for human patients paralyzed by strokes, spinal-cord injuries and degenerative neuromuscular disease.

Best visual illusion of the year

Check out the Best Visual Illusion of the Year contest.....

Thursday, June 26, 2008

The brain's default network - a review

Buckner et al. offer a review of work what our brains are doing when we are not focused on the external environment. This is an open access article in a new annual volume, "The Year in Cognitive Neuroscience," being initiated by the New York Academy of Sciences. (Table of contents of this first issue is here. ) I am passing on the abstract and one central figure and legend from the article:
Thirty years of brain imaging research has converged to define the brain's default network—a novel and only recently appreciated brain system that participates in internal modes of cognition. Here we synthesize past observations to provide strong evidence that the default network is a specific, anatomically defined brain system preferentially active when individuals are not focused on the external environment. Analysis of connectional anatomy in the monkey supports the presence of an interconnected brain system. Providing insight into function, the default network is active when individuals are engaged in internally focused tasks including autobiographical memory retrieval, envisioning the future, and conceiving the perspectives of others. Probing the functional anatomy of the network in detail reveals that it is best understood as multiple interacting subsystems. The medial temporal lobe subsystem provides information from prior experiences in the form of memories and associations that are the building blocks of mental simulation. The medial prefrontal subsystem facilitates the flexible use of this information during the construction of self-relevant mental simulations. These two subsystems converge on important nodes of integration including the posterior cingulate cortex. The implications of these functional and anatomical observations are discussed in relation to possible adaptive roles of the default network for using past experiences to plan for the future, navigate social interactions, and maximize the utility of moments when we are not otherwise engaged by the external world. We conclude by discussing the relevance of the default network for understanding mental disorders including autism, schizophrenia, and Alzheimer's disease.

The default network is activated by diverse forms of tasks that require mental simulation of alternative perspectives or imagined scenes. Four such examples from the literature illustrate the generality. (A) Autobiographical memory: subjects recount a specific, past event from memory. (B) Envisioning the future: cued with an item (e.g., dress), subjects imagine a specific future event involving that item. (C) Theory of mind: subjects answer questions that require them to conceive of the perspective (belief) of another person. (D) Moral decision making: subjects decide upon a personal moral dilemma. Note that all the studies activate strongly PCC/Rsp and dMPFC. Active regions also include those close to IPL and LTC, although further research will be required to determine the exact degree of anatomic overlap. It seems likely that these maps represent multiple, interacting subsystems.

More from the great curmudgeon...

To follow up my June 15 post, here is an Esquire Magazine "What I have learned" offering from Gore Vidal that my colleague Jim Steakley alterted me to. A few selections:
God has been expelled. I think he knows when he’s on a losing wicket.
I went into a line
of work in which jealousy is the principle emotion between practitioners. I don’t think I ever suffered from it, because there was no need. But I was aware of it in others, and I found it a regrettable fault.
There was more
of a flow to my output of writing in the past, certainly. Having no contemporaries left means you cannot say, “Well, so-and-so will like this,” which you do when you’re younger. You realize there is no so-and-so anymore. You are your own so-and-so. There is a bleak side to it.
You hear
all this whining going on, “Where are our great writers?” The thing I might feel doleful about is: Where are the readers?
Some of my father’s
fellow West Pointers once asked him why I turned out so well, his secret in raising me. And he said, “I never gave him any advice, and he never asked for any.” We agreed on nothing, but we never quarreled once.
Every fool
I knew had gone to university. I didn’t think it necessary. I’d seen some of the results, you know?
When I was young,
I was bored shitless with being desired by others. I don’t look in the mirror anymore.
I lived with Howard
for fifty years, but what we had was certainly not romantic love, not passionate love. And it certainly was nonsexual. Try and explain that to the fags.
Nonprofit status
is what created the Bible Belt. The tax code brought religion back to this country.
When she was running for the Senate,
Hillary’s psephologists discovered that the one group that really hated her was white, middle-aged men of property. She got the whole thing immediately -- I heard she said, “I remind them of their first wife.”
“You got to meet everyone -- Jackie Kennedy, William Burroughs.” People always put that sentence the wrong way around. I mean, why not put it the true way, that these people got to meet me, and wanted to? Otherwise it sounds like I spent my life hustling around trying to meet people: “Oh, look, there’s the governor.
For a writer, memory is everything. But then you have to test it; how good is it, really? Whether it’s wrong or not, I’m beyond caring. It is what it is. As Norman Mailer would say, “It’s existential.” He went to his grave without knowing what that word meant.
We’re the most captive nation
of slaves that ever came along. The moral timidity of the average American is quite noticeable. Everybody’s afraid to be thought in any way different from everyone else.
Get rid of religion.
It’ll do you no good.
As the Greeks sensibly believed,
should you get to know yourself, you will have penetrated as much of the human mystery as anyone need ever know.
I wasn’t like everyone,
you know. What everyone did, I was sure not to do.

Wednesday, June 25, 2008

A memorial for our president...

I simply can't resist passing this on - an article on a proposal, naturally hatched in a bar, to change the name of a prize-winning water treatment plant on the shoreline of San Francisco to the George W. Bush Sewage Plant. This is a memorial you can contribute to from your bathroom. The proposal has enough signatures to qualify it as an initiative on the November ballot.

Retaliation for unfairness - depends on serotonin

Nature highlights an article by Crockett et al. showing that serotonin modulates our reaction to unfairness. The experimenters:
...temporarily lowered serotonin (5-HT) levels in 20 volunteers and had them play the part of responder in the 'ultimatum game'. The responder can either accept the division of a sum of money offered by the game's proposer, in which case they both get their share, or reject it and deprive both players of the amounts proposed.

Although mood, fairness judgments, basic reward processing, or response inhibition, remained unchanged when players' serotonin levels were lowered, they were more likely to reject unfair and very unfair offers, defined as 30% and 20% of the stake, respectively.

Trust in oxytocin.

I pass on a brief news review by Leonie Welberg from Nature Neuroscience:
The neuropeptide oxytocin is released during childbirth, suckling, touch and orgasm, suggesting that it might have a 'pro-social' function. This idea was strengthened by a recent study in Nature (see my 2/13/06 post, or enter oxytocin inthe search box in the left column of this blog), which showed that an oxytocin nasal spray caused people playing a 'trust' game to retain their trust in a stranger who was looking after their money, even though this trust was violated on many occasions. At the same time, the oxytocin spray decreased activity in the amygdala and the caudate nucleus, brain areas that are involved in the regulation of fear and decision making, respectively.

"We now know ... what exactly is going on in the brain when oxytocin increases trust," says lead researcher Thomas Baumgartner of the University of Zürich, Switzerland. "It seems to diminish our fears." (BBC News, 21 May 2008.) As humans are typically averse to taking social risks, "...a little bit of oxytocin may facilitate carrying on relationships with others," according to Mauricio Delgado, a neuroscientist at Rutgers University in Newark, New Jersey. (ScienceNOW, 21 May 2008.)

How people in real-life situations develop and retain trust in others is another question, however. "They certainly don't do it by spraying stuff up each other's noses," says Paul Zak of the Center for Neuroeconomics Studies at Claremont Graduate University in California. (Science News, 21 May 2008.)

Nevertheless, the findings have implications for understanding mental disorders in which deficits in social behaviour are observed and "...could provide a bridge for potential clinical applications," thinks Delgado (BBC News). An oxytocin spray might help people with a social phobia or autism. "Autistic people also have a fear of social situations and have problems interacting, so it is very likely that oxytocin could help," says Baumgartner. "This hormone seems to play a very specific role in social situations so might be able to improve autism." (BBC News.)

Tuesday, June 24, 2008

Are the religionists lightening up?

The graphic is from Banerjee's NYTimes summary of the Pew Forum report. The good news is that while the vast majority of Americans (many more than Western Europeans) believe in "God" and eternal life, more accept that there are varieties of Pearly Gates, and how you might get to them. Better yet, fewer get anthropomorphic about it, citing 'an impersonal force' as closer to their idea of God, and thus might be more friendly to the sort of emergence models mentioned in the previous post.

Can 'emergence' put spirituality back into nature?

The anti-reductionist view of emergence undergoes cycles of popularity as a philosophical topic. Valerie Hardcastle gives a rather critical review (in Jour. Consciousness Studies, Vol. 14, No. 11, pp.119-122) of a recent collection "The Re-Emergence of Emergence - The Emergentist Hypothesis from Science to Religion" edited by Clayton and Davies (Oxford Univ. Press, 2006). This emergentism is 'feel good' stuff. I think most of us get a bit frightened and a bit dried and shriveled up at the implications of strong reductionism in which all the explanatory arrows point down. Reversing the reductionist’s causal arrow with a comprehensive theory of emergence and self-organization that breaks no laws of physics and yet cannot be explained by them is a laudable project, but as Hardcastle wryly notes, one that continues to fail the "where's the beef" test.

Michael Shermer offers a very appealing gloss in his "Skeptic" column in the Scientific American, with the title: Sacred Science - Can emergence break the spell of reductionism and put spirituality back into nature? He specifically reviews a new book by Stuart Kauffman, Reinventing the Sacred (Basic Books, 2008). Denis Noble also reviews Kauffman's book in Science Magazine. Here are some clips from Shermer's column:
...reverses the reductionist’s causal arrow with a comprehensive theory of emergence and self-organization that Kaufman says “breaks no laws of physics” and yet cannot be explained by them. God “is our chosen name for the ceaseless creativity in the natural universe, biosphere and human cultures.” In Kauffman’s emergent universe, reductionism is not wrong so much as incomplete. It has done much of the heavy lifting in the history of science, but reductionism cannot explain a host of as yet unsolved mysteries, such as the origin of life, the biosphere, consciousness, evolution, ethics and economics... How would a reductionist explain the biosphere, for example? “One approach would be, following Newton, to write down the equations for the evolution of the biosphere and solve them. This cannot be done,” Kauffman avers. “We cannot say ahead of time what novel functionalities will arise in the biosphere. Thus we do not know what variables—lungs, wings, etc.—to put into our equations. The Newtonian scientific framework where we can prestate the variables, the laws among the variables, and the initial and boundary conditions, and then compute the forward behavior of the system, cannot help us predict future states of the biosphere.”... This problem is not merely an epistemological matter of computing power, Kauffman cautions; it is an ontological problem of different causes at different levels. Something wholly new emerges at these higher levels of complexity.

Similar ontological differences exist in the self-organized emergence of consciousness, morality and the economy...economics and evolution are complex adaptive systems that learn and grow as they evolve from simple to complex...they are autocatalytic, containing self-driving feedback loops...such phenomena “cannot be deduced from physics, have causal powers of their own, and therefore are emergent real entities in the universe.” This creative process of emergence, Kauffman contends, “is so stunning, so overwhelming, so worthy of awe, gratitude and respect, that it is God enough for many of us. God, a fully natural God, is the very creativity in the universe.”
Shermer ends noting that Kaufman's:
God 2.0 is a deity worthy of worship. But I am skeptical that it will displace God 1.0, Yahweh, whose Bronze Age program has been running for 6,000 years on the software of our brains and culture.

Monday, June 23, 2008

Brain exercise/fitness links...

Tom Hanson, the Editor of, asks me to pass on these two separate posts on brain exercise/fitness, noting some firms that I have mentioned previously, and so I do this as a professional courtesy.

Strengths and Limits of fMRI studies on the brain

Nikos Logothetis offers a long and detailed discussion of what we can and cannot learn from brain imaging approaches. I'm giving a few clips from his discussion:
fMRI is not and will never be a mind reader, as some of the proponents of decoding-based methods suggest, nor is it a worthless and non-informative 'neophrenology' that is condemned to fail, as has been occasionally argued.

The principal advantages of fMRI lie in its noninvasive nature, ever-increasing availability, relatively high spatiotemporal resolution, and its capacity to demonstrate the entire network of brain areas engaged when subjects undertake particular tasks. One disadvantage is that, like all haemodynamic-based modalities, it measures a surrogate signal whose spatial specificity and temporal response are subject to both physical and biological constraints. A more important shortcoming is that this surrogate signal reflects neuronal mass activity.

Figure - Two slices of GE-EPI demonstrating the high functional signal-to-noise ratio (SNR) of the images, but also the strong contribution of macrovessels. The yellow areas (indicated with the green arrows) are pia vessels, an example of which is shown in the inset scanning electron microscopy image (total width of inset, 2 mm). For the functional images red indicates low and yellow indicates high.

MRI may soon provide us with images of a fraction of a millimetre (for example, 300 x 300 mum2 with a couple of millimetres slice thickness or 500 x 500 x 500 mum3 isotropic), which amount to voxel volumes of about two–three orders of magnitude smaller than those currently used in human imaging. With an increasing number of acquisition channels such resolution may ultimately be attained in whole-head imaging protocols, yielding unparalleled maps of distributed brain activity in great regional detail and with reasonable—a couple of seconds—temporal resolution. Would that be enough for using fMRI to understand brain function?

The answer obviously depends on the scientific question and the spatial scale at which this question could be addressed—"it makes no sense to read a newspaper with a microscope", as neuroanatomist Valentino Braitenberg once pointed out. To understand the functioning of the microcircuits in cortical columns or of the cell assemblies in the striosomes of basal ganglia, one must know a great deal about synapses, neurons and their interconnections. To understand the functioning of a distributed large-scale system, such as that underlying our memory or linguistic capacities, one must first know the architectural units that organize neural populations of similar properties, and the interconnections of such units. With 1010 neurons and 1014 connections in the cortex alone, attempting to study dynamic interactions between subsystems at the level of single neurons would probably make little sense, even if it were technically feasible. It is probably much more important to understand better the differential activity of functional subunits—whether subcortical nuclei, or cortical columns, blobs and laminae—and the instances of their joint or conditional activation. If so, whole-head imaging with a spatial resolution, say, of 0.7 times 0.7 mm2 in slices of 1-mm thickness, and a sampling time of a couple of seconds, might prove optimal for the vast majority of questions in basic and clinical research. More so, because of the great sensitivity of the fMRI signal to neuromodulation. Neuromodulatory effects, such as those effected by arousal, attention, memory, and so on, are slow and have reduced spatiotemporal resolution and specificity.
Logothesis offers a concluding perspective.
The limitations of fMRI are not related to physics or poor engineering, and are unlikely to be resolved by increasing the sophistication and power of the scanners; they are instead due to the circuitry and functional organization of the brain, as well as to inappropriate experimental protocols that ignore this organization. The fMRI signal cannot easily differentiate between function-specific processing and neuromodulation, between bottom-up and top-down signals, and it may potentially confuse excitation and inhibition. The magnitude of the fMRI signal cannot be quantified to reflect accurately differences between brain regions, or between tasks within the same region. The origin of the latter problem is not due to our current inability to estimate accurately cerebral metabolic rate of oxygen (CMRO2) from the BOLD signal, but to the fact that haemodynamic responses are sensitive to the size of the activated population, which may change as the sparsity of neural representations varies spatially and temporally. In cortical regions in which stimulus- or task-related perceptual or cognitive capacities are sparsely represented (for example, instantiated in the activity of a very small number of neurons), volume transmission (see Supplementary Information)—which probably underlies the altered states of motivation, attention, learning and memory—may dominate haemodynamic responses and make it impossible to deduce the exact role of the area in the task at hand. Neuromodulation is also likely to affect the ultimate spatiotemporal resolution of the signal.

This having been said, and despite its shortcomings, fMRI is currently the best tool we have for gaining insights into brain function and formulating interesting and eventually testable hypotheses, even though the plausibility of these hypotheses critically depends on used magnetic resonance technology, experimental protocol, statistical analysis and insightful modelling. Theories on the brain's functional organization (not just modelling of data) will probably be the best strategy for optimizing all of the above. Hypotheses formulated on the basis of fMRI experiments are unlikely to be analytically tested with fMRI itself in terms of neural mechanisms, and this is unlikely to change any time in the near future.

Saturday, June 21, 2008

Neuro-puffs and neuropundits...

Check out this debunking of neuroimaging research on things like political partisanship and superbowl commercials.

Friday, June 20, 2008

A new perspective on culture-specific behavior

Yamagishi et al. demonstrate that the East Asian "preference" for conformity is actually a default strategy to avoid accrual of negative reputation. When the possibility for negative evaluations in a given situation was clearly defined, cultural differences in the tendency for uniqueness disappeared. The framework for analyzing the motivations for choices made by Japanese and Americans in a simple task is described in a summary in Science.
When offered a single colored pen from a group of five pens as a token payment for filling out a survey, Hokkaido students were less likely than Wolverines (Michigan students) to take a particular pen if it were the only one of that color available--that is, they would avoid reducing the scope of choice for subsequent people and thus, by incurring the cost of passing up the uniquely colored pen, not run the risk of making a negative impression on others. In contrast, a cultural psychological assessment would explain this outcome as revealing the preference (higher valuation) that East Asians place on conformity as opposed to the affinity of Westerners for individualism. When the choice task was expanded to include situations where the student was told explicitly that he was the first or the last of the five students to receive pens, the East-West difference disappeared; both Japanese and Americans were less likely to take the uniquely colored if they were the first and more likely (equally so) if they were the last to choose.
Yamagishi et al. suggest that:
... while cultural psychological perspectives are commendable for bringing culture into the mainstream of psychology, they have tended to be oversimplistic in attributing the cause of culture-specific behaviors to internalized cultural norms and values.
Their approach to the issue of the culturally grounded nature of human behavior is:
... from a game-theoretic perspective, and proposes an institutional approach as an alternative to the cultural psychology approach. The institutional approach to cultural differences views culture-specific behavior as strategies adapted to a set of collectively created social incentives. In this framework, no psychological concepts such as self-construals are required to interpret cultural differences, and thus the institutional approach can provide a more parsimonious explanation of cultural differences that can extend toward social science disciplines outside of psychology.

Thursday, June 19, 2008

A population genetic analysis of male homosexuality

As a companion to the previous post, I pass along this article by Ciani et al. arguing that only a two-locus genetic model for male homosexuality with at least one locus on the X chromosome, in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all the known empirical data. That data is interesting (as described in this account in Slate):
It starts with four curious patterns. First, male homosexuality occurs at a low but stable frequency in a wide range of societies. Second, the female relatives of gay men produce children at a higher rate than other women do. Third, among these female relatives, those related to the gay man's mother produce children at a higher rate than do those related to his father. Fourth, among the man's male relatives, homosexuality is more common in those related to his mother than in those related to his father.

More on gay and straight brains.

A recent study notes that in several measures of brain symmetry, straight men and gay women were similar, and gay men and straight women were similar. MindHacks points out a further interesting feature: that amygdala reactivity to simply breathing unscented air (thus having nothing obvious to do with sexual preference or activity per se) is different in gay and straight men and women. This is yet more evidence that sexual preference is not determined solely by individual developmental experience. Here is the complete abstract of the Savic and Per Lindström article, followed by the PET scan amygdala data, which speaks for itself, and finally a clip from the discussion. PDF of article here.
Cerebral responses to putative pheromones and objects of sexual attraction were recently found to differ between homo- and heterosexual subjects. Although this observation may merely mirror perceptional differences, it raises the intriguingquestion as to whether certain sexually dimorphic features in the brain may differ between individuals of the same sex but different sexual orientation. We addressed this issue by studying hemispheric asymmetry and functional connectivity, two parameters that in previous publications have shown specific sex differences. Ninety subjects [25 heterosexual men (HeM) and women (HeW), and 20 homosexual men (HoM) and women (HoW)] were investigated with magnetic resonance volumetry of cerebral and cerebellar hemispheres. Fifty of them also participated in PET measurements of cerebral blood flow, used for analyses of functional connections from the right and left amygdalae. HeM and HoW showed a rightward cerebral asymmetry, whereas volumes of the cerebral hemispheres were symmetrical in HoM and HeW. No cerebellar asymmetries were found. Homosexual subjects also showed sex-atypical amygdala connections. In HoM, as in HeW, the connections were more widespread from the left amygdala; in HoW and HeM, on the other hand, from the right amygdala. Furthermore, in HoM and HeW the connections were primarily displayed with the contralateral amygdala and the anterior cingulate, in HeM and HoW with the caudate, putamen, and the prefrontal cortex. The present study shows sex-atypical cerebral asymmetry and functional connections in homosexual subjects. The results cannot be primarily ascribed to learned effects, and they suggest a linkage to neurobiological entities.

From the discussion:
HeW and HoM displayed more pronounced between-amygdala connections and greater connections with the anterior cingulate, the subcallosum, and the hypothalamus. This connectivity pattern provides a strong substrate for processing of external stimuli that are relayed by the two amygdalae and represents a possible pathway for their functional interconnection in HeW and HoM. The remarkable similarity between HeW and HoM in the connectivity pattern deserves special attention. The amygdala has a key role in emotional reactions to external stimuli, including stress; the subcallosum and the anterior cingulate, on the other hand, are highly involved in mediation of mood and anxiety-related processes. Affective disorders are 2–3 times more common in women than men, and the tight functional connections between the amygdala and cingulate in women is currently discussed as a possible neurobiological substrate for their higher vulnerability, in addition to the effects of estrogen and testosterone. Interestingly, the incidence of depression and suicide attempts is elevated in homosexual subjects, and HoM in particular. Although the underlying mechanisms are likely to be multifactorial and include social pressure, the presently observed similarity with HeW vis-a`-vis the amygdala connectivity motivates further evaluations.

Wednesday, June 18, 2008

A new mind blog...

At the risk of promoting further blog overload, I've added the Psychology Today blog to the 'other mind blogs' list just under 'Archives' in the right column. It has some good stuff.

Increasing complexity of nerve synapses during evolution

Nicholas Wade points to the work of Grant and colleagues on how the complexity of nerve interconnections (synapses) has increased during evolution as the variety of their protein components has increased from a few to several hundred. Vertebrate synapses have about 1,000 different proteins, assembled into 13 molecular machines, one of which is built from 183 different proteins. The human brain has about 100 billion neurons, interconnected at 100 trillion synapses. Grant provides an analogy:
If the synapses are thought of as the chips in a computer, then brainpower is shaped by the sophistication of each chip, as well as by their numbers...From the evolutionary perspective, the big brains of vertebrates not only have more synapses and neurons, but each of these synapses is more powerful — vertebrates have big Internets with big computers and invertebrates have small Internets with small computers.

The top part of the figure (click to enlarge) shows the phylogenetic relationships of the species studied. The number of varieties of two signaling complexes, NMDA receptor (NRC or MASC) / postsynaptic density (PSD) are in parentheses. The lower half shows the occurrences of PSD and MASC homologs found in each of the 19 species as a percentage of those found in human.

Evolutionary Psychology as Maladapted Psychology

Bolhuis reviews a book with the title of this post by philosopher Robert Richardson. (I have read a longer excellent book, "Adapting Minds", by philosopher David Buller. Here are some clips from the review:
Evolutionary psychology aims to apply evolutionary theory to the human mind. Specifically, it proposes that the mind consists of cognitive modules that evolved in response to selection pressures faced by our Stone Age ancestors. The approach has a wide popular appeal, perhaps because it often addresses such exciting topics as human desire, sex, and passion....Richardson readily acknowledges that our psychological capacities are evolved traits subject to natural selection. But at the same time, he maintains that there is very little we can find out about the evolution of the mind and that the evolutionary psychology interpretation is wrong from the perspective of evolutionary biology...he criticizes mainly the methods used by evolutionary psychologists, weighing the approach's theoretical framework using criteria from evolutionary biology...The main problem with evolutionary psychology is that it usually does not consider alternative explanations but takes the assumption of adaptation through natural selection as given.

Richardson rightly suggests that paleontologists are unlikely to unearth the evidence that can inform us about the social structure of our ancestral communities. I think one can go a step further. Even if we would be able to muster the evidence needed for an evolutionary psychological analysis of human cognition, it would not tell us anything about our cognitive mechanisms. The study of evolution is concerned with a historical reconstruction of traits. It does not, and cannot, address the mechanisms that are involved in the human brain. Those fall within the domains of neuroscience and cognitive psychology. In that sense, evolutionary psychology will never succeed, because it attempts to explain mechanisms by appealing to the history of these mechanisms. To use the author's words, "We might as well explain the structure of orchids in terms of their beauty." In this excellent book, Richardson shows very clearly that attempts at reconstruction of our cognitive history amount to little more than "speculation disguised as results." The book's title implies that the field is itself subject to selection pressure. Richardson is certainly piling it on.

Tuesday, June 17, 2008

Anticipating the Future to ‘See’ the Present

The title of this post is also the title of an article by Benedict Carey that describes works supporting the idea that the brain uses a bag of ad hoc tricks to build a streaming model of the world. Because it takes the brain at least a tenth of a second to model visual information, it is always working with old information. The argument is that the brain has evolved to meet this problem by projecting or guessing a split second into the future when it perceives motion. By modeling the future during movement, it is “seeing” the present. These two illusions illustrate the process:

Leaning toward the image makes it appear as if it is bulging.

The radiating lines trick the brain into perceiving motion forward, so the center appears to bulge.

Evaluating mental exercises

This article on pumping up your little grey cells in the Times of London is worth reading, also this New Scientist article.

Monday, June 16, 2008

Schizophrenia and the Brain

Here is a very nice instructional video from Thompson at UCLA, whose images I have shown in previous posts, showing brain developmental differences in normal and schizophrenic children between the ages of 4 and 21. It also shows how recently developed drugs inhibit the degenerative changes.

Social cognition in plants?

I suppose it is a bit of a stretch to call it social cognition, but it is recognition of kin and non-kin species, now discovered in plants. This is a bit of a shock, in part because most animals have not even been shown to have the ability to recognize relatives, despite the huge advantages in doing so. Some plants not only avoid competing with kin by not sending roots towards them, but also sniff out their victims. We're talking about careful experiments here, not New Age fantasies about plant feelings and sentience. Check out the account by Yoon. This excerpt is from its ending:
Recent debates have revolved around a longstanding question: which of the abilities and attributes that scientists have long considered the realm of just animals, like sensing, learning and memory, can sensibly be transferred to plants?...At the extreme of the equality movement, but still within mainstream science, are the members of the Society of Plant Neurobiology, a new group whose Web site describes it as broadly concerned with plant sensing....The very name of the society is enough to upset many biologists. Neurobiology is the study of nervous systems — nerves, synapses and brains — that are known just in animals. That fact, for most scientists, makes the notion of plant neurobiology a combination of impossible, misleading and infuriating....Thirty-six authors from universities that included Yale and Oxford were exasperated enough to publish an article last year, “Plant Neurobiology: No Brain, No Gain?” in the journal Trends in Plant Science. The scientists chide the new society for discussing possibilities like plant neurons and synapses, urging that the researchers abandon such “superficial analogies and questionable extrapolations.”

Defenders point out that 100 years ago, some scientists were equally adamant that plant physiology did not exist. Today, that idea is so obviously antiquated that it could elicit a good chuckle from the many scientists in that field...As for the “superficial analogies,” the new wave botanists are well aware that plants do not have exact copies of animal nervous systems...“No one proposes that we literally look for a walnut-shaped little brain in the root or shoot tip,” five authors wrote in defense of the new group. Instead, the researchers say, they are asking that scientists be open to the possibility that plants may have their own system, perhaps analogous to an animal’s nervous system, to transfer information around the body....“Plants do send electrical signals from one part of the plant to another,” said Dr. Eric D. Brenner, a botanist at the New York Botanical Garden and a member of the Society of Plant Neurobiology...Although those signals have been known for 100 years, scientists have no idea what plants do with them...“No one’s asked how all that information is integrated in a plant, partly because we’ve convinced ourselves that it isn’t,” Dr. Brenner said. “People have been intimidated from asking that question.”

Sunday, June 15, 2008

A great curmudgeon of our times...

This Deborah Solomon interview with Gore Vidal cracked me up so much I wanted to pass it on:

Q: At the age of 82, you will be publishing your new collection of essays this week, which seems likely to confirm your reputation as one of America’s last public intellectuals. Why do you think that critics have traditionally praised your essays more than your fiction, which includes “Burr,” “Myra Breckinridge” and 20 other novels? That’s because they don’t know how to read. I can’t name three first-rate literary critics in the United States . I’m told there are a few hidden away at universities, but they don’t print them in The New York Times .
Are you saying your novels have been critically neglected? I don’t even read most reviews, unless there is a potential lawsuit on view. I’ve never had much attention paid by critics — nor has anybody else in the United States of America, as Mr. Obama likes to call it.
And what about Mr. McCain? Disaster. Who started this rumor that he was a war hero? Where does that come from, aside from himself? About his suffering in the prison war camp?
Everyone knows he was a prisoner of war in North Vietnam. That’s what he tells us.
Why would you doubt him? He’s a graduate of Annapolis. I know a lot of the Annapolis breed. Remember, I’m West Point, where I was born. My father went there.
So what does that have to do with the U.S. Naval Academy down in Annapolis? The service universities keep track of each other, that’s all. They have views about each other. And they are very aware of social class and eventually money, since they usually marry it.
How, exactly, is your cousin Al Gore related to you? They keep explaining it to me, and I keep forgetting.
What about your grandfather, Thomas Gore of Oklahoma ? He invented the whole state. It was Indian territory. There was no state until Senator Gore.
In 1968, during the Nixon-Humphrey race, you became the voice of liberalism in a series of televised debates with William Buckley. Any plans to be a pundit at the coming presidential conventions? No.
How did you feel when you heard that Buckley died this year? I thought hell is bound to be a livelier place, as he joins forever those whom he served in life, applauding their prejudices and fanning their hatred.
You live in California , where last month the State Supreme Court overturned the ban on same-sex marriage . As someone who lived with a male companion for 50-plus years, do you see this as a victory for equality? People would ask, How could you live with someone for so long without any problems of any kind? I said, There was no sex.
Were you chaste during those years? Chased by whom?
Are you a supporter of gay marriage? I know nothing about it. I don’t follow that.
Why doesn’t it interest you? The same reason heterosexual marriage doesn’t seem to interest me.
If we look at the situation apart from you — It’s my interview, so we’ve got to stay with me.
Have you ever considered leaving the United States permanently? No, it’s my subject.
Do you read a lot of contemporary fiction these days? Like everyone else, no, I don’t.
Anyone in the 20th century you might have a kind word about? Yes, I liked Italo Calvino, and I thought he was the greatest writer of my time.
Your new collection includes an essay in which you note, “Calvino does what very few writers can do: he describes imaginary worlds with the most extraordinary precision and beauty.” What about American novelists? Can’t think of one.
Norman Mailer? Oh, dear, we’re not going to go into pluses and minuses now.
Philip Roth? Ditto.
I admire Roth. He never became complacent. He had no reason to. He’s a good comic writer.
What do you think is your own best novel? I don’t answer questions like that. Ever. And you ought not to ask them.
Well, it was a great pleasure talking to you. I doubt that.

Friday, June 13, 2008

Incense is psychoactive.

Mechoulam and colleagues find that incensole acetate (IA), an ingredient of Boswellia resin (frankincense), stimulates a little understood brain ion channel (TRPV3) to cause anti-anxiety and antidepressive behaviors in mice. This suggest that TRPV3 channels in the brain may play a role in emotional regulation. IA has no effect on 27 other receptors, ion channels, and transport proteins in the brain. The suggests the potential for an entirely new class of depression and anxiety drugs.

Obama and Neuroeconomics

In the New York Review of Books John Cassidy offers an interesting review of Nudge: Improving Decisions About Health, Wealth, and Happiness by Richard H. Thaler and Cass R. Sunstein.
If Obama isn't an old-school Keynesian, what is he? One answer is that he is a behavioralist—the term economists use to describe those who subscribe to the tenets of behavioral economics, an increasingly popular discipline that seeks to marry the insights of psychology to the rigor of economics...One of the reasons this approach has proved so popular is that it appears to provide a center ground between the Friedmanites and the Keynesians, whose intellectual jousting dominated economics for most of the twentieth century...Thaler and Sunstein lay out a number of principles that can be used to encourage better choice-making, and they apply them to various topical issues, including retirement saving, health care, and the environment. In a number of cases, the measures that Thaler and Sunstein recommend are mirrored by proposals in Obama's voluminous policy papers, which can be downloaded from his Web site.

Thursday, June 12, 2008

Why Are Conservatives Happier Than Liberals?

Napier and Jost offer an interesting perspective in their article in Psychological Science. Here is an edited excerpt from their general discussion:
In three studies, using nationally representative samples from the United States and nine additional countries, we consistently found that conservatives (or right-wingers) are happier than liberals (or left-wingers). This ideological gap in happiness is not accounted for by demographic differences or by differences in cognitive style (liberals becoming less satisfied with their current situation because of the deleterious effects of rumination and introspection - versus conservatives tending to prefer relatively simple, unambiguous answers to life's questions). We did find, however, that the rationalization of inequality—a core component of conservative ideology — helps to explain why conservatives are, on average, happier than liberals. These findings are consistent with system-justification theory, which posits that viewing the status quo (with its attendant degree of inequality) as fair and legitimate serves a palliative function. The studies suggest that conservatism provides an emotional buffer against the negative hedonic impact of inequality in society.

The relation between political orientation and self-reported happiness as a function of the Gini inequality index, 1974 through 2004.

Only a theory!

Toasting the Joys of Imbibing Properly

Check out this review by Dwight Garner of "EVERYDAY DRINKING - The Distilled Kingsley Amis". The book deals with more than the physical manifestations of a hangover:
...What also urgently needs to be treated, he observed, is the metaphysical hangover — “that ineffable compound of depression, sadness (these two are not the same), anxiety, self-hatred, sense of failure and fear for the future” that looms on the grizzled morning after...Amis recommended, among other things, a course of “hangover reading,” one that “rests on the principle that you must feel worse emotionally before you start to feel better. A good cry is the initial aim."..Thus he suggested beginning with Milton — “My own choice would tend to include the final scene of ‘Paradise Lost,’ ” he wrote, “with what is probably the most poignant moment in all our literature coming at lines 624-6” — before running through Aleksandr Solzhenitsyn, Eric Ambler and, finally, a poulticelike application of light comedies by P. G. Wodehouse and Peter De Vries.

Wednesday, June 11, 2008

Seeing ourselves / Seeing others - built in errors

Emily Pronin writes a review article in Science Magazine to which my first reaction was "Duh... so what else is new?" But as I looked at it a second time my "who needs to write this down, it is just common sense" reaction began to yield to realizing that the sort of systematic list she offers is useful - way in which intrinsic differences in 1st person (introspective, immersed in our own sensations, emotions, and cognitions) and 3rd person perspectives (extrospective, dominated by what behavior can be observed externally) are guaranteed to lead conflicts in judgements of our own and others behavior. Here are a few clips:
Positive illusions. People tend to have inflated views of themselves and their futures. For example, they think that they are more likely to become wealthy, and less likely to contract contagious diseases, than those around them. This unrealistic optimism partially stems from people's attentional focus on their own (but not others') internal desires and intentions .

Interpersonal knowledge. People overestimate how much they can learn about others from brief encounters such as job interviews (10). At the same time, they think others can get only a glimpse of them from such encounters. As a result, people generally feel they know others better than others know them

Pluralistic ignorance. People often misconstrue the thoughts and motives of others. In cases of "pluralistic ignorance," those misconstruals occur even though others share one's own motives and beliefs and act in the same way as oneself . An example... occurs when an audience of people all succeed in concealing their distraction and boredom during a long lecture and they then assume that they are the only ones not interested and engaged. In another example, college students often forgo trying to make friends with students of other races (even though they would like to be friends) because they interpret those others' lack of trying as indicating lack of interest. Both these examples involve people judging others based on overt behavior (e.g., failing to make social overtures) but themselves based on internal states (e.g., wanting friendship but fearing rejection)

Miscommunications. People often fail miserably in their efforts to communicate. These communication breakdowns (whether they involve negotiating peace agreements, giving driving directions, or navigating romantic relationships) often reflect the fact that people know what they intend or mean to communicate, while others focus on what they actually say. For example, negotiators can fail to outwardly express their interest in cooperating, because their internal awareness of that interest (gained through introspection) blinds them to the fact that the other side sees only their behavior, which often lacks clear signs of that motive

Conformity. People are influenced by those around them (and by the mass media) in everything from fashion tastes to political views; but, they generally deny that and see themselves as alone in a crowd of sheep.

Conclusions. It is almost axiomatic that as long as people are in a position to perceive themselves and to perceive others, differences in those perceptions will exist and will engender disagreement, misunderstanding, and conflict. When people judge themselves based on their good intentions but others based on their less-good behavior (or based on cynical assumptions about human nature), they are likely to feel resentful and disappointed over others' failure to meet them halfway. When people view their own perceptions and beliefs as objective reflections of reality but others' as distorted by bias, they are likely to feel frustrated and angry over others' unwillingness to be fair and reasonable. And, such feelings are likely to breed aggression and conflict.

This picture may sound dismal, but there is hope. Misunderstandings can be averted by those aware of the psychological processes involved in self and social perception. Those individuals can be mindful that it is not only their own behavior that is sensitive to the constraints of the situation, but others' as well. Perhaps this could prompt them to show more charity when others fail to meet expectations. Those individuals also can recognize that others' mistakes and errors may not be the result of conscious malice but rather of unintended influences that those others would themselves decry. And, those individuals might remind themselves that there often is a wide gulf between intention and action, but that it is only reasonable and fair to apply the same standard of judgment to others as to oneself. Following these guidelines would not just be socially charitable— it would also be scientifically informed.

Dan Dennett: Ants, terrorism, and the awesome power of memes

My son Jonathan sent me this link to an engaging talk by Dan Dennett given some time ago. I heard it back then, and think it is worth passing on...

Tuesday, June 10, 2008

Valse Romantique

Debussy. Someone who listened my recording of this on YouTube asked how to get the sheet music to this piece, and as I sent them the information and listened it again, I decided to relay it on to MindBlog as a bit of relief from the more brainy stuff.

Growing new brain cells enhanced by social contact

From the editor's choice section of the May 30 issue of Science, a suggestion that increased social input from a larger number of other animals enhances the survival of new brain cells in brain areas involved in communication:
Out With the Old, In With the New

Might this adage, which some pundits have claimed as the basis for the vernal electoral calamities that have befallen the Labour Party in the United Kingdom, apply equally forcefully to the turnover of neurons in the brain? Adar et al. have performed a painstaking histological and immunofluorescence accounting of the survival likelihoods of newly born neurons in the brain of the zebra finch, a songbird that serves as an animal model for studying innate and learned influences on vocal communication. They focused on the nidopallium caudale (NC) region because it participates in auditory processing and is activated by social stimuli (other songbirds in this notably social species). By varying the complexity of the social environment, they found that the youngest cells--which had recently migrated from the site of their birth and were still becoming integrated, quite literally, as they established syn-aptic connections with existing NC neurons--were more likely to have survived if the bird had been exposed to a large group of male and female birds; conversely, in birds housed with only one other individual, the survival of older (though still relatively young) cells was enhanced. One interpretation of these data is that an increase in demand--in the form of an upturn in auditory/social inputs needing to be processed--acts as a selective pressure favoring the survival of new recruits.

The neural circuits of free choice

We often face alternatives that we are free to choose between. Planning movements to select an alternative involves several areas in frontal and parietal cortex. Pesaran et al. have looked at activity of single brain neurons in these areas when monkeys are free to choose which movement among several alternatives to make versus when they are following instructions. Correlations between simultaneously recorded spikes and local field potentials in dorsal premotor and parietal reach regions (which are anatomically connected into long-range circuits) increase during the free choice condition. They propose that a decision circuit featuring a sub-population of cells in frontal and parietal cortex may exchange information to coordinate activity between these areas, with cells participating in this decision circuit influencing movement choices by providing a common bias to the selection of movement goals.

Monday, June 09, 2008

The futurist: machines as smart as ourselves

John Tierney does a nice write up of the debate over the ideas of futurist Ray Kurzweil. (I've always thought that Kurzweil was simple proof of the proposition that if you propose any 10 crazy things, one of them will turn out to be right. People remember the correct prophesy, and forget the mistakes.) Still.... the guy has been right on a number of times. Here is part of the discussion of our cognitive/emotional repertoire being bested by machines ( (possibly piggybacked onto our biological hardware). This event is referred to as "the singularity." Kurzweil proposes that: the 2020s we’ll be adding computers to our brains and building machines as smart as ourselves...This serene confidence is not shared by neuroscientists like Vilayanur S. Ramachandran, who discussed future brains with Dr. Kurzweil at the festival. It might be possible to create a thinking, empathetic machine, Dr. Ramachandran said, but it might prove too difficult to reverse-engineer the brain’s circuitry because it evolved so haphazardly...“My colleague Francis Crick used to say that God is a hacker, not an engineer,” Dr. Ramachandran said. “You can do reverse engineering, but you can’t do reverse hacking.”...Dr. Kurzweil’s predictions come under intense scrutiny in the engineering magazine IEEE Spectrum, which devotes its current issue to the Singularity. Some of the experts writing in the issue endorse Dr. Kurzweil’s belief that conscious, intelligent beings can be created, but most think it will take more than a few decades....He is accustomed to this sort of pessimism and readily acknowledges how complicated the brain is. But if experts in neurology and artificial intelligence (or solar energy or medicine) don’t buy his optimistic predictions, he says, that’s because exponential upward curves are so deceptively gradual at first.

“Scientists imagine they’ll keep working at the present pace,” he told me after his speech. “They make linear extrapolations from the past. When it took years to sequence the first 1 percent of the human genome, they worried they’d never finish, but they were right on schedule for an exponential curve. If you reach 1 percent and keep doubling your growth every year, you’ll hit 100 percent in just seven years.”

Dr. Kurzweil is so confident in these curves that he has made a $10,000 bet with Mitch Kapor, the creator of Lotus software. By 2029, Dr. Kurzweil wagers, a computer will pass the Turing Test by carrying on a conversation that is indistinguishable from a human’s.
You should also check out John Horgan's caustic comments on the whole singularity bit in a special IEEE spectrum feature, which ends with:
Let's face it. The singularity is a religious rather than a scientific vision. The science-fiction writer Ken MacLeod has dubbed it “the rapture for nerds,” an allusion to the end-time, when Jesus whisks the faithful to heaven and leaves us sinners behind.

Such yearning for transcendence, whether spiritual or technological, is all too understandable. Both as individuals and as a species, we face deadly serious problems, including terrorism, nuclear proliferation, overpopulation, poverty, famine, environmental degradation, climate change, resource depletion, and AIDS. Engineers and scientists should be helping us face the world's problems and find solutions to them, rather than indulging in escapist, pseudoscientific fantasies like the singularity.

Sarcasm and the right parahippocampal gyrus...

Getting inside someone's else's head to realize when they are ironic, sarcastic, or angry is one of our most advanced 'theory of mind' capabilities. You would expect the brain imaging people to show the frontotemporal lobe to light up when sarcasm is being detected, since one of the early signs of frontotemporal dementia is loss of the ability to detect sarcasm. Hurley describes the work of Rankin and others looking at brain correlates of being able to detect sarcasm based entirely on paralinguistic (non-verbal) cues (check out the link to the videos used).
...magnetic resonance scans revealed that the part of the brain lost among those who failed to perceive sarcasm was not in the left hemisphere of the brain, which specializes in language and social interactions, but in a part of the right hemisphere previously identified as important only to detecting contextual background changes in visual tests....The right parahippocampal gyrus must be involved in detecting more than just visual context — it perceives social context as well....The discovery fits with an increasingly nuanced view of the right hemisphere’s role...The left hemisphere does language in the narrow sense, understanding of individual words and sentences...But it’s now thought that the appreciation of humor and language that is not literal, puns and jokes, requires the right hemisphere.

So is it possible that Jon Stewart, who wields sarcasm like a machete on “The Daily Show,” has an unusually large right parahippocampal gyrus?..“His is probably just normal,” Dr. Rankin said. “The right parahippocampal gyrus is involved in detecting sarcasm, not being sarcastic...I bet Jon Stewart has a huge right frontal lobe; that’s where the sense of humor is detected on M.R.I.”...A spokesman for Mr. Stewart said he would have no comment — not that a big-shot television star like Jon Stewart would care about the size of his neuroanatomy.

Friday, June 06, 2008

Social heirarchy, stress, and diet

I become increasingly convinced over time that much of what runs our behavior is is the same stuff that runs a macaque monkey, with the human self conscious rationalizing overlay mainly being a window dressing. This is why I find numerous bits of work that have emerged from Yerkes Primate Research group (the subject of this and other previous posts) so fascinating.

A recent report from Wilson et al. is an extension of work by Seligman and many others that has shown that one's role in a hierarchy, or relative position in a gradient of personal helplessness to power, is a fundamental determinant of individual well being in both animal and human societies. Subordinate individuals show more chronic stress, anxiety-like behaviors, and susceptibility to disease. Wilson et al. show that socially subordinate macaque females consume more high caloric food and weigh more, and feed both during daylight and night (unlike dominants) .

Tierney notes the similarity of this result and the famous Whitehall study of British civil servants, which found that lower-ranking workers were more obese than higher-status workers. Even though the subordinate workers were neither poor nor lacked health care, their lower status correlated with more health problems. He also mentions the experiments of Zellner, who:
...tested both men and women by putting bowls of potato chips, M&Ms, peanuts and red grapes on a table as the participants in the study worked on solving anagrams. Some of the people were given unsolvable anagrams, and they understandably reported being more stressed than the ones given easy anagrams...The stress seemed to affect snacking in different ways for each sex. The women given solvable puzzles ate more grapes than M&Ms, while the women under stress preferred M&Ms. The men ate more of the high-fat snacks when they were not under stress, apparently because the ones who got the easy anagrams had more time to relax and have a treat.

Spatial memory requires new nerve cells.

At least this appears to be the case in mice. Here is the abstract from Dupre et al.
The dentate gyrus of the hippocampus is one of the few regions of the mammalian brain where new neurons are generated throughout adulthood. This adult neurogenesis has been proposed as a novel mechanism that mediates spatial memory. However, data showing a causal relationship between neurogenesis and spatial memory are controversial. Here, we developed an inducible transgenic strategy allowing specific ablation of adult-born hippocampal neurons. This resulted in an impairment of spatial relational memory, which supports a capacity for flexible, inferential memory expression. In contrast, less complex forms of spatial knowledge were unaltered. These findings demonstrate that adult-born neurons are necessary for complex forms of hippocampus-mediated learning.
(More specifically, the experiments involved generating transgenic mice that selectively overexpressed the pro-apoptotic protein Bax in neural precursor cells in an inducible manner. Overexpression of Bax removed newly born cells in the adult dentate gyrus and caused a strong deterioration in the relational processing of spatial information in the Morris water maze. Animals were unaffected when tested on simpler forms of spatial knowledge; nor were they affected in tasks where memory could be acquired without the hippocampus.)

Thursday, June 05, 2008

Sex differences in judging attractiveness - brain correlates

When selecting mates, men place greater importance on attractiveness than do women, whereas women favor status and resources more so than men. The reasons behind these differences can be rationalized from both evolutionary and sociocultural perspectives. Cloutier et al use fMRI to examine the possibility that attractive faces of the opposite sex simply have different reward value for men and women. They show that brain reward circuits (nucleus accumbens [NAcc], orbito-frontal cortex [OFC]) exhibit a linear increase in activation with increased judgments of attractiveness. Their analysis further reveals sex differences in the recruitment of OFC, which distinguished attractive and unattractive faces only for male participants. In short, brain regions involved in identifying the potential reward value of a stimulus are more active when men view attractive women than when women view attractive men.

Figure - Axial sections display the left NAcc (top) and right NAcc (middle) and a sagittal section displays mOFC (bottom) spherical regions of interest superimposed on normalized anatomic images. Graphs to the right of each image display signal change (parameter estimates) for attractive and unattractive faces across female and male participants relative to the baseline fixation. Error bars indicate standard error of the mean. Activity in the left and right NAcc was greater for attractive than unattractive faces irrespective or the participants' sex. Activity in the mOFC exhibited an interaction between facial attractiveness and participant sex displaying greater activity for attractive than unattractive faces only for male participants.

Body odors - brain processing different from similar common odors

Here is an edited paste-up of text and abstract from Lundström et al.
Humans are highly accurate at identifying individuals based solely on their body odors, being able to use signals conveyed in body odor to make accurate kin–nonkin judgments, and to detect minute differences in genetic composition of unknown individuals. While visual and auditory stimuli of high social and ecological importance are processed in the brain by specialized neuronal networks, such specialized processing has not yet been demonstrated for olfactory stimuli. The authors used positron emission tomography to ask whether the central processing of body odors differs from perceptually similar non-body odors as women smelled odors collected from friends and non-friends who had slept for seven nights with tight cotton t-shirts with cotton nursing pads sewn into the underarm area. Body odors activated a network consisting of the posterior cingulate cortex, occipital gyrus, angular gyrus, and the anterior cingulate cortex, none of which is believed to be related to olfactory processing. However, together they form an interesting pattern. Posterior cingulate cortex is known to be active in response to emotional stimuli, whereas the anterior cingulate cortex is believed to regulate attentional efforts. This suggests processing of body odors is similar to what previously has been demonstrated for highly emotional stimuli, such as visual images of snakes, where the posterior cingulate cortex works in concert with the anterior cingulate cortex. A separation in the processing of odors based on their source was observed. Smelling a friend's body odor activated regions previously seen for familiar stimuli, whereas smelling a stranger activated amygdala and insular regions akin to what has previously been demonstrated for fearful stimuli.

The data provide evidence that social olfactory stimuli of high ecological relevance are processed by specialized neuronal networks, just as has been demonstrated for auditory and visual stimuli.

Wednesday, June 04, 2008

Update on resveratrol and aging...

Check out Nicholas Wade's article in today's NY Times. It includes mention of the report in a PLoS ONE article by Prolla and Weindruch's group here at Wisconsin that both caloric restriction and low amounts of resveratrol (near the amount of resveratrol and resveratrol-like compounds found in a 5 ounce glass of red wine) are sufficient to inhibit gene expression profiles associated with cardiac and skeletal muscle aging, and prevent age-related cardiac dysfunction. Dietary resveratrol also mimics the effects of caloric restriction in insulin mediated glucose uptake in muscle.

Brain Rules

I've been sent a review copy of "Brain Rules" by John Medina. The book, which includes a DVD, is an exuberant and entertaining hodgepodge of material thrown together out of which the author extracts "12 Principles for Surviving and Thriving at Work, Home, and School." The DVD has a perky in your face Dr. Medina leading you through the storyline. It is an enjoyable self help book, I think aimed at hooking readers less sophisticated than most of you who read this blog. A companion website offers supplemental material and references supporting each brain rule. (I find the references idiosyncratic and a bit dated). Here are the author's bottom line rules:
EXERCISE | Rule #1: Exercise boosts brain power.
SURVIVAL | Rule #2: The human brain evolved, too.
WIRING | Rule #3: Every brain is wired differently.
ATTENTION | Rule #4: We don't pay attention to boring things.
SHORT-TERM MEMORY | Rule #5: Repeat to remember.
LONG-TERM MEMORY | Rule #6: Remember to repeat.
SLEEP | Rule #7: Sleep well, think well.
STRESS | Rule #8: Stressed brains don't learn the same way.
SENSORY INTEGRATION | Rule #9: Stimulate more of the senses.
VISION | Rule #10: Vision trumps all other senses.
GENDER | Rule #11: Male and female brains are different.
EXPLORATION | Rule #12: We are powerful and natural explorers.

Healing and sedative effects of music.

An article by David Dobbs describes the work of musician/surgeon Claudius Conrad, who suggests that music may exert healing and sedative effects partly through a paradoxical stimulation of a growth hormone generally associated with stress rather than healing. His study, published in Critical Care Medicine:
...was fairly simple. The researchers fitted 10 postsurgical intensive-care patients with headphones, and in the hour just after the patients’ sedation was lifted, 5 were treated to gentle Mozart piano music while 5 heard nothing...The patients listening to music showed several responses that Dr. Conrad expected, based on other studies: reduced blood pressure and heart rate, less need for pain medication and a 20 percent drop in two important stress hormones, epinephrine and interleukin-6, or IL-6. Amid these expected responses was the study’s new finding: a 50 percent jump in pituitary growth hormone...The question is whether the jump in growth hormone actually drives the sedative effect or is part of something else going on.

Tuesday, June 03, 2008

The Evolution of Music

In the May 15 issue of Nature Josh McDermott discusses ideas about the evolution of music:
The mere presence of music in every known culture implies some genetic basis. But music varies dramatically from culture to culture, and many aspects of musical behaviour seem at best only weakly constrained by genetics. Whereas our ability to hear pitch intervals, for instance, could well be biologically rooted in the hardware of the auditory system, our emotional response to particular scales or chords seems likely to be acquired from exposure to a particular culture. Interactions between genes and environment are complex, and unravelling their contributions is not easy, but studies of music in different cultures and of musical development offer some hope.

A number of interesting music-related traits emerge in human infants with fairly minimal musical input, providing some evidence for innate constraints. Babies notice when the notes of a melody are reordered, but not when they are shifted to a different pitch range. Infants, like adults, are sensitive to the relationships between notes, which is preserved in transposition, but altered by reordering. Infants also tend to be captivated by music relative to many other stimuli. Not all music is equivalent to them — they prefer combinations of notes that are judged by adults to sound pleasing, or consonant (the perfect fifth, for instance), over combinations that are less pleasing, or dissonant (a minor second). Infants may even extract metre from music: they react when the rhythm changes from a march to a waltz.
Universal appeal

Features of music that occur repeatedly around the world despite the substantial cultural variation in music also provide clues to genetically constrained mechanisms. Lullabies seem to qualify as a rare universal — nearly every culture has a genre of music geared towards infants, and there is considerable consistency in how they sound, generally being slow, repetitive and featuring descending pitch contours. Other features that are common, if not completely universal, among cultures include the inclination to dance to music, musical metre, and the hierarchical organization of pitch, giving structural prominence to particular notes over others.

Neurobiology of trust

The June 2008 issue of Scientific American has an article by Zak on the neurobiology of trust, and the hormone oxytocin. I've previously mentioned Zak's work, and if you enter 'oxytocin' in MindBlog's search box in the left column you will pull up numerous previous posts on oxytocin, trust, and affiliative behaviors, some of which the Zak article mentions (for example, inhaling a nasal spray containing oxytocin increases trusting behaviors). I thought I would show one graphic from the article relevant to the fact that trust is among the strongest known predictors of a country’s wealth. Nations with low levels tend to be poor. Societies with low levels are poor because the inhabitants undertake too few of the long-term investments that create jobs and raise incomes. Such investments depend on mutual trust that both sides will fulfill their contractual obligations.

Monday, June 02, 2008

Brief Bach, and its piano and windows

A Bach two-part invention (No. 8)

Do chimpanzees have a theory of mind? 30 years later

Call and Tomasello offer a review in the May issue of Trends in Neuroscience on the controversial question of how much our nearest relatives understand about the minds of others:
On the 30th anniversary of Premack and Woodruff's seminal paper asking whether chimpanzees have a theory of mind, we review recent evidence that suggests in many respects they do, whereas in other respects they might not. Specifically, there is solid evidence from several different experimental paradigms that chimpanzees understand the goals and intentions of others, as well as the perception and knowledge of others. Nevertheless, despite several seemingly valid attempts, there is currently no evidence that chimpanzees understand false beliefs. Our conclusion for the moment is, thus, that chimpanzees understand others in terms of a perception–goal psychology, as opposed to a full-fledged, human-like belief–desire psychology.
Here is one description of an experimen showing that Chimpanzees infer a human's intentions:
Buttelmann et al. [Dev. Sci. 10 (2007 pp. F31–F38]...tested six human-raised chimpanzees in the so-called rational-imitation paradigm. The chimpanzees were shown how to operate an apparatus to produce an interesting result (e.g. lights or sounds), and then they were given a turn. The most natural behavior for them in all cases was to operate it with their hands. But this obvious behavior was never demonstrated for them; they always saw a human manipulate the apparatus in a novel way with some other body part. The idea was that in some cases the physical constraints of the situation dictated that the human (referred to as ‘E’ in the figure) had to use that unusual body part; for example, he had to turn on a light with his head because his hands were occupied holding a blanket or he had to operate a light with his foot because his hands were occupied with a heavy bucket (see Figure I). When the chimpanzees saw this forced use of the unusual body part, they mostly discounted it and used their hands as they normally would (because the constraints were not present for them). However, when they saw the human use the unusual body part when there was no physical constraint dictating this, they quite often copied the unusual behavioral means themselves. If we interpret this experiment the way it is interpreted for human infants, the conclusion is that the chimpanzees understood not only what the experimenter was trying to do (his goal) but also why he was doing it in the way he was doing it – the rationality behind the choice of the plan of action toward the goal. According to Tomasello et al. [Behav. Brain Sci. 28 (2005), pp. 675–691], an understanding of the action plan chosen toward a goal constitutes an understanding of the intention.