Wednesday, September 30, 2009

Green Porno.

In the 25 Sept. issue of Science Magazine, the Gonzo Scientist points us to these humorous performances on the Sundance channel (worth checking out) by Isabella Rossellini. She offers a series of brief video performances, between 1 and 2 minutes long, in which she dresses in elaborate animal costumes to paint a miniportrait of several organisms, describing key features of their physiology and behavior - in particular their reproductive biology.

A new chemical fix for chronic depression??

Maybe, for mice. With the results possibly relevant to us. There is evidence, obtained from both post-mortem human brains and from animal experiments, that persistent depression may involve long term chemical changes in gene-protein complexes called chromatin. Covington et al find that chronic social defeat stress in mice causes a transient decrease, followed by a persistent increase, in levels of acetylated histone H3 (a chromatin protein) in the nucleus accumbens, an important limbic brain region. They then find that infusion into this region of inhibitors of the enzyme that removes acetate groups lessens behavioral symptoms of depression and also reverses the effects of chronic defeat stress on global patterns of gene expression in the nucleus accumbens.

Out of Africa

The Sept. 22 issue of P.N.A.S. has a special section of articles on human evolution. The abstract of Ian Tattersall's introductory to this section has a nice summary:

Our species, Homo sapiens, is highly autapomorphic (uniquely derived) among hominids in the structure of its skull and postcranial skeleton. It is also sharply distinguished from other organisms by its unique symbolic mode of cognition. The fossil and archaeological records combine to show fairly clearly that our physical and cognitive attributes both first appeared in Africa, but at different times. Essentially modern bony conformation was established in that continent by the 200–150 Ka range (a dating in good agreement with dates for the origin of H. sapiens derived from modern molecular diversity). The event concerned was apparently short-term because it is essentially unanticipated in the fossil record. In contrast, the first convincing stirrings of symbolic behavior are not currently detectable until (possibly well) after 100 Ka. The radical reorganization of gene expression that underwrote the distinctive physical appearance of H. sapiens was probably also responsible for the neural substrate that permits symbolic cognition. This exaptively acquired potential lay unexploited until it was “discovered” via a cultural stimulus, plausibly the invention of language. Modern humans appear to have definitively exited Africa to populate the rest of the globe only after both their physical and cognitive peculiarities had been acquired within that continent.

Tuesday, September 29, 2009

Nutrition and Violence

In the Sept. 25 issue of Science John Bohannon describes work of Oxford's Bernard Gesch and others studying prison populations for evidence of links between nutrition and violent behavior. Two previous studies have shown that prisoners given nutritional supplements committed ~35% fewer violent incidences than those given a placebo, and a more ambitious study of over 1,000 prisoners in three U.K. prisons started this spring. The article offers a summary table which I pass on here:

How would you control eight legs?

It's a problem, if you are an octopus, because you have the challenge of controlling eight appendages that can assume an almost limitless number of positions. Zulio et al. (the paper has a neat video) show that the octopus brain takes a very different tack from our own. Instead of having a specific body part controlled by a specific area of the the brain (as in our brains), the control of complex, coordinated movements is consolidated into specific areas of the nervous system. They placed 35 electrodes to micro-stimulate higher motor centers (in the basal lobes)in free moving animals. Low-voltage stimulation of different areas evokes simple responses, such as a change in skin colour or small eyelid movements. Higher voltages elicit more complex responses, such as inking and jet-propelled swimming. Discrete and complex components have no central topographical organization but are distributed over wide regions. They found no stimulation site where movements of a single arm or body part could be elicited.

The Mind and LIfe Institute

Here is the link to download the Autumn 2009 Newsletter of the Mind and Life Institute. It describes the Mind and Life Education and Research Network, a multidisciplinary intellectual forum dedicated to investigating issues at the intersection of mind, brain, education and contemplative practice.

Monday, September 28, 2009

Size matters...

I work out every day in the university gym, where in the shower room it is obvious that the large more macho males subtly (or not so subtly) check out the 'packages' of their shower mates. Here's the payoff in another species, illustrated by Kahn et al.'s study showing that female mate preference in mosquitofish is influenced by size of male genitalia. The tested female preference for males that had had their genitalia considerably reduced in size by surgery compared with those with only a minor reduction (see figure). They found that females spent, on average, around one-and-a-half times longer associating with the better-endowed males. This preference was, however, only expressed when females chose between two large males; for small males, there was no effect of genital size on female association time.

Representative G. holbrooki showing the difference between wild-type (not used in trials) and treatment male gonopodia. (a) Wild-type; (b) minor reduction; (c) major reduction. Scale bar 1 mm.

Watch those shots of booze!

I've always been curious about the attraction that shots of sugar and alcohol (peppermint schnaps, etc.) have for adolescent drinkers. Now we have a possible animal model for this behavior: Rats fed tasty 'jelly shots' containing alcohol during adolescence became bigger risk-takers than teetotaller rats when presented with a lever game designed by Bernstein et. al. When the adult rats were faced with a choice between pressing a lever for a guaranteed two sugar pills or a lever that could give them either nothing or four sugar pills, the individuals exposed to alcohol in adolescence tended to gamble more often. This effect on behavior could still be seen three months after the alcohol was discontinued. The results indicate that the risk-taking behavior is caused by the alcohol. Here is the abstract of the work:

Individuals who abused alcohol at an early age show decision-making impairments. However, the question of whether maladaptive choice constitutes a predisposing factor to, or a consequence resulting from, alcohol exposure remains open. To examine whether a causal link exists between voluntary alcohol consumption during adolescence and adult decision making the present studies used a rodent model. High levels of voluntary alcohol intake were promoted by providing adolescent rats with access to alcohol in a palatable gel matrix under nondeprivation conditions. A probability-discounting instrumental response task offered a choice between large but uncertain rewards and small but certain rewards to assess risk-based choice in adulthood either 3 weeks or 3 months following alcohol exposure. While control animals' performance on this task closely conformed to a predictive model of risk-neutral value matching, rats that consumed high levels of alcohol during adolescence violated this model, demonstrating greater risk preference. Evidence of significant risk bias was still present when choice was assessed 3 months following discontinuation of alcohol access. These findings provide evidence that adolescent alcohol exposure may lead to altered decision making during adulthood and this model offers a promising approach to the investigation of the neurobiological underpinnings of this link.

Friday, September 25, 2009

Acting against our real self interest to preserve our self image

Here is a fascinating bit of game playing from Yamagishi et al. :

In a series of experiments, we demonstrate that certain players of an economic game reject unfair offers even when this behavior increases rather than decreases inequity. A substantial proportion (30–40%, compared with 60–70% in the standard ultimatum game) of those who responded rejected unfair offers even when rejection reduced only their own earnings to 0, while not affecting the earnings of the person who proposed the unfair split (in an impunity game). Furthermore, even when the responders were not able to communicate their anger to the proposers by rejecting unfair offers in a private impunity game, a similar rate of rejection was observed. The rejection of unfair offers that increases inequity cannot be explained by the social preference for inequity aversion or reciprocity; however, it does provide support for the model of emotion as a commitment device. In this view, emotions such as anger or moral disgust lead people to disregard the immediate consequences of their behavior, committing them to behave consistently to preserve integrity and maintain a reputation over time as someone who is reliably committed to this behavior.

Mindblog backlog...

Here is my second offering of links to a few bits of work that I find interesting, but that are so far down my list of potential blog postings that they are unlikely to make it into a regular post, and might be of interest to some MindBlog readers.

Cognitive fitness of cost-efficient brain functional networks

Superior task performance was positively correlated with global cost efficiency of the β-band network (15-30 Hz) and specifically with cost efficiency of nodes in left lateral parietal and frontal areas. These results are consistent with biophysical models highlighting the importance of β-band oscillations for long-distance functional connections in brain networks and with pathophysiological models of schizophrenia as a dysconnection syndrome. More generally, they echo the saying that “less is more”: The information processing performance of a network can be enhanced by a sparse or low-cost configuration with disproportionately high efficiency.
Do we really need vision? How blind people "see" the actions of others.
Our mirror neuron system develops in the absence of sight.
A 35,000 year old flute.
Fragments of ancient flutes reveal that music was well established in Europe by about 40,000 years ago.
Keeping in Touch with One's Self: Multisensory Mechanisms of Self-Consciousness
More from the laboratory that brought you the full body illusion.
Two related papers:
Neural Substrates of Mounting Temporal Expectation

Ready…Go: Amplitude of the fMRI Signal Encodes Expectation of Cue Arrival Time

Thursday, September 24, 2009

A new positive psychology website

You might want to check out the launch of a new self help website happiness.com. It has the support of gurus in the happiness field such as Martin Seligman, and offers its own particular set of happiness exercises and plans. It's hard to find fault with the simple exercises and suggestions offered; and indeed, whenever I take the attention space to spend some time doing common exercises in the field, like feeling or expressing gratitude or kindness, savoring small joys, forgiving, avoiding over thinking and social comparison, etc. it lightens me up considerably. However, one of the features of these sites that kind of gets to me is their Pollyanna aura, with the apparent goal of being 100% happy 100% of the time - of making 'sad' just go away....it seems to me that the spice of life is having robust highs and lows. I enjoy my lighter moments and I also savor my basically curmudgeonly nature.

Observing the brain pathway that lowers anxiety

Kim and Whalen publish an interesting study in the Journal of Neuroscience using diffusion tensor imaging to show that the structural integrity, or strength, of a pathway between the prefrontal cortex and the amygdala correlates with lower trait anxiety in individual subjects (the idea being that this pathway allows prefrontal cortex to inhibit amygdala reactivity to anxiety provoking stimuli). The abstract:

Here, we used diffusion tensor imaging (DTI) and showed that the strength of an axonal pathway identified between the amygdala and prefrontal cortex predicted individual differences in trait anxiety. A functional magnetic resonance imaging (fMRI) functional localizer that has been shown to produce reliable amygdala activation was collected in 20 psychiatrically healthy subjects. Voxelwise regression analyses using this fMRI amygdala reactivity as a regressor were performed on fractional anisotropy images derived from DTI. This analysis identified a white matter pathway between the amygdala and ventromedial prefrontal cortex. Individual differences in the structural integrity of this putative amygdala–prefrontal pathway were inversely correlated with trait anxiety levels (i.e., higher pathway strength predicted lower anxiety). More generally, this study illustrates a strategy for combining fMRI and DTI to identify individual differences in structural pathways that predict behavioral outcomes.

A unique area for tool use in human versus monkey brains

Peeters et al. observe an activation in the left inferior parietal lobule when humans observe tool use, absent in monkeys doing the same observation, which they suggest is related to our capacity to understand the causal relationship between tools and the result of their use.

Though other species of primates also use tools, humans appear unique in their capacity to understand the causal relationship between tools and the result of their use. In a comparative fMRI study, we scanned a large cohort of human volunteers and untrained monkeys, as well as two monkeys trained to use tools, while they observed hand actions and actions performed using simple tools. In both species, the observation of an action, regardless of how performed, activated occipitotemporal, intraparietal, and ventral premotor cortex, bilaterally. In humans, the observation of actions done with simple tools yielded an additional, specific activation of a rostral sector of the left inferior parietal lobule (IPL). This latter site was considered human-specific, as it was not observed in monkey IPL for any of the tool videos presented, even after monkeys had become proficient in using a rake or pliers through extensive training. In conclusion, while the observation of a grasping hand activated similar regions in humans and monkeys, an additional specific sector of IPL devoted to tool use has evolved in Homo sapiens, although tool-specific neurons might reside in the monkey grasping regions. These results shed new light on the changes of the hominid brain during evolution.

Wednesday, September 23, 2009

More on Brain Boosters

Gary Stix has written a review article for the Oct. 2009 issue of the Scientific American titled "Turbocharging the Brain", a topic that has been the subject of several previous mindblog posts. Here are two simple summary figures on effects and risks (click on figure to enlarge):


and on potential new drugs:

Bird brains get even more clever.

New Caledonian crows, already known for clever tool-making in the wild and in the lab, are now shown to be able of using three tools in the correct order to bag a treat. Such sequential tool use has never been observed in any other untrained nonhuman animal. In the wild, the crows (Corvus moneduloides) regularly fashion barbs and hooks from leaves and twigs to extract grubs from holes and crevices. In the new experiments, each of seven crows was given a test tube stuffed with a tasty piece of meat that could be pried out only with a particular stick. To get at the meat, the birds had to do three things in the right order: pick up a short stick, available on the cage floor, and use it to pull a longer stick out of a second test tube; use that stick to extract an even longer stick from a third test tube; and then use this longest stick to get the prize. Four crows were successful. It seems unlikely that they were selecting sticks at random, because they usually swapped sticks for longer ones.

Tuesday, September 22, 2009

Societal trend of media multitasking is changing our cognitive control

Lin reviews some interesting work of Ophir et al. showing:

...that heavy media multitaskers (HMMs) performed worse on task switching than light media multitaskers (LMMs), likely because of HMMs' reduced ability to filter out interference from irrelevant stimuli and representations in memory. Their findings are surprising in that, intuitively, HMMs should be better at task switching (i.e., multitasking) because they frequently switch between tasks, a habit or expertise (if so) that should have helped them to be better multitaskers (task switchers). However, the findings are also not surprising in that...HMMs tend to be breadth-biased in their behaviors and are inclined to pay attention to a larger scope of information instead of focusing on a particular piece of information. Such a behavior or habit has conditioned them to be less selective when it comes to filtering information and tasks in front of them. In other words, HMMs may have developed a habit of treating all of the information in front of them with equal (or almost equal) amounts of attention instead of focusing their attention steadily on a particular task. As a result, they performed worse than LMMs did when they were asked to focus attention on selective pieces.

Mood elevating endorphine release greater with social than with solitary exercise

The Research Highlights section of the Sept. 17 issue of Nature points to work by Cohen et al.:

Coordinated social activity, such as dancing or team sports, stimulates the brain to release high levels of mood-elevating endorphins that are believed to have a role in social bonding. But how can this be distinguished from the normal release of endorphins during exercise?...Emma Cohen of the University of Oxford, UK, and her colleagues looked at rowers training alone or with teammates on stationary rowing machines. Because measuring endorphins directly would require a spinal tap, the researchers instead used pain tolerance to gauge endorphin release after workouts. They found that rowers had greater increases in pain threshold after operating as a crew than when going solo.
Cohen et al. suggest that enhanced endorphin release from synchronized activity may explain the sense of euphoria experienced in social activities like laughter, music-making, and dancing that are involved in social bonding in humans (and possibly other vertebrates.)

MRI of emotions in a dead fish...

Even though this gem is making the rounds of the blogosphere it is worth pointing to again here. (This reminds me of my grandmother's answer to my "what do the people do here?" question as we were driving through small Texas towns. Her reply: "They take in each other's laundry." )

Bennett et. al. present a hilarious yet serious abstract showing different brain MRI responses as a dead salmon views pictures of people with different emotional expressions. It is a demonstration of the "multiple comparisons problem" - the fact that if you do a lot of different statistical tests, some of them will, just by chance, give interesting results. A multiple comparisons corrections can be applied, but many fMRI publications still report "uncorrected" results.

Monday, September 21, 2009

Will there ever be a "healthy" diet?

Darn.... here I've been religiously avoiding potatoes, pasta, bread, etc in my diet, and now Rosenzweig and his Harvard colleagues find evidence that low carbohydrate diets are linked to atherosclerosis and impaired blood vessel growth. They find that mice placed on a 12-week low-carbohydrate/high-protein diet showed a significant increase in atherosclerosis, a buildup of plaque in the heart’s arteries and a leading cause of heart attack and stroke. The findings also showed that the diet led to an impaired ability to form new blood vessels in tissues deprived of blood flow, as might occur during a heart attack.

Rewards work better than punishment in enhancing cooperation

Rand and colleagues have examined cooperation among 192 participants in a public goods game probing the fundamental tension between the interests of an individual and a group. In more than 50 rounds of interaction, each of four participants in a group would decide how much to contribute toward a common pool that benefited all four equally. Each participant was then able — at a cost to himself or herself — to either reward or punish each of the three other subjects for their contributions to the group, or lack thereof. Here is their abstract:

The public goods game is the classic laboratory paradigm for studying collective action problems. Each participant chooses how much to contribute to a common pool that returns benefits to all participants equally. The ideal outcome occurs if everybody contributes the maximum amount, but the self-interested strategy is not to contribute anything. Most previous studies have found punishment to be more effective than reward for maintaining cooperation in public goods games. The typical design of these studies, however, represses future consequences for today’s actions. In an experimental setting, we compare public goods games followed by punishment, reward, or both in the setting of truly repeated games, in which player identities persist from round to round. We show that reward is as effective as punishment for maintaining public cooperation and leads to higher total earnings. Moreover, when both options are available, reward leads to increased contributions and payoff, whereas punishment has no effect on contributions and leads to lower payoff. We conclude that reward outperforms punishment in repeated public goods games and that human cooperation in such repeated settings is best supported by positive interactions with others.

Friendship networks revealed by cell phone data.

Lazer and colleagues have compared data gathered through self-reporting versus data gathered through cell phone usage to determine whether such information can prove reliable in predicting friendships and job satisfaction. The study followed 94 subjects over the course of nine months.

Data collected from mobile phones have the potential to provide insight into the relational dynamics of individuals. This paper compares observational data from mobile phones with standard self-report survey data. We find that the information from these two data sources is overlapping but distinct. For example, self-reports of physical proximity deviate from mobile phone records depending on the recency and salience of the interactions. We also demonstrate that it is possible to accurately infer 95% of friendships based on the observational data alone, where friend dyads demonstrate distinctive temporal and spatial patterns in their physical proximity and calling patterns. These behavioral patterns, in turn, allow the prediction of individual-level outcomes such as job satisfaction.

Friday, September 18, 2009

Bad health is good business

Everyone should read this Michael Pollan article. Just two classic clips:

...food system reform has not figured in the national conversation about health care reform...the government is putting itself in the uncomfortable position of subsidizing both the costs of treating Type 2 diabetes and the consumption of high-fructose corn syrup.

There’s lots of money to be made selling fast food and then treating the diseases that fast food causes...As things stand, the health care industry finds it more profitable to treat chronic diseases than to prevent them. There’s more money in amputating the limbs of diabetics than in counseling them on diet and exercise.

This reminds me of the British Empire's 19th century Chinese tea for Indian opium scam that made opium addicts of the chinese.

At risk for pathological gambling.

I had not realized that treating Parkinson's disease or restless legs syndrome with dopamine agonists (mimics or enhancers) has been associated with impulse control disorders and pathological gambling. Abler et al. look at correlative changes in the brain:

We scanned 12 female restless leg syndrome patients without a history of pathological gambling. All patients were scanned twice: once whilst taking their regular medication with low dose dopamine receptor agonists and once after a washout phase interval. They performed an established gambling game task involving expectation and receipt or omission of monetary rewards at different levels of probabilities. Upon expectation of rewards, reliable ventral striatal activation was detected only when patients were on, but not when patients were off medication....Chronic dopamine receptor agonist medication changed the neural signalling of reward expectation predisposing the dopaminergic reward system to mediate an increased appetitive drive.

What if you were born with only one cerebral hemisphere?

Wolf Singer and collaborators have examined a woman whose right cerebral hemisphere did not develop after birth. Normally this hemisphere would receive information about the left visual field. From their abstract:

Despite the complete loss of her right hemisphere (di- and telencephalon) at birth, the patient's remaining hemisphere has not only developed maps of the contralateral (right) visual hemifield but, surprisingly, also maps of the ipsilateral (left) visual hemifield. Retinal ganglion-cells changed their predetermined crossing pattern in the optic chiasm and grew to the ipsilateral LGN. In the visual cortex, islands of ipsilateral visual field representations were located along the representations of the vertical meridian. In V1, smooth and continuous maps from contra- and ipsilateral hemifield overlap each other, whereas in ventral V2 and V3 ipsilateral quarter field representations invaded small distinct cortical patches. This reveals a surprising flexibility of the self-organizing developmental mechanisms responsible for map formation.

Thursday, September 17, 2009

We are the ones we've been waiting for?

That messianic phrase from Obama's campaign turns out not to pan out very well, as illustrated particularly by the current health care debate. Anand Giridharadas notes that web participatory democracy has yielded some rather embarrassing results so far:

During the transition, the administration created an online “Citizen’s Briefing Book” for people to submit ideas to the president. “The best-rated ones will rise to the top, and after the Inauguration, we’ll print them out and gather them into a binder like the ones the president receives every day from experts and advisors,” Valerie Jarrett, a senior adviser to Mr. Obama, wrote to supporters...They received 44,000 proposals and 1.4 million votes for those proposals. The results were quietly published, but they were embarrassing — not so much to the administration as to us, the ones we’ve been waiting for...In the middle of two wars and an economic meltdown, the highest-ranking idea was to legalize marijuana, an idea nearly twice as popular as repealing the Bush tax cuts on the wealthy. Legalizing online poker topped the technology ideas, twice as popular as nationwide wi-fi. Revoking the Church of Scientology’s tax-exempt status garnered three times more votes than raising funding for childhood cancer.

Yet another theory on why we sleep

Among the functions of sleep suggested are memory consolidation and repair of neuronal wear and tear. Jerome Siegel offers a rationale for why the duration of sleep varies so much between animals. From Carey's reivew:

Why should lions get 15 hours a night and giraffes just 5 — when it is the giraffes who will be running for their lives come hunting time? How on earth do migrating birds, in flight for days on end, sleep? Why is it that some people are early birds as young adults and night owls when they’re older?

[Siegel]...argues that sleep evolved to optimize animals’ use of time, keeping them safe and hidden when the hunting, fishing or scavenging was scarce and perhaps risky. In that view, differences in sleep quality, up to and including periods of insomnia, need not be seen as problems but as adaptations to the demands of the environment...Consider the big brown bat, perhaps the longest-sleeping mammal of them all. It snoozes 20 hours a day, and spends the other 4 hunting mosquitoes and moths in the dusk and early evening. Increased waking time would seem to be highly maladaptive for this animal, since it would expend energy and be exposed to predatory birds with better vision and better flight abilities.

In humans, it is well known that sleep quality changes with age, from the long, deep plunges of early childhood to the much lighter, more frequently interrupted five or six hours that many elderly people call a night’s sleep...In Dr. Siegel’s view, it’s a matter of tradeoffs: older people no longer have a child’s need to grow, which requires deep, long sleep and may have more need and more ability to do things for themselves instead.

Why do we swear? For pain relief.

An interesting little nugget from Scientific American Mind.

Wednesday, September 16, 2009

Social contagion - Is happiness (or obesity) catching?

Clive Thompson does a nice article in this past Sunday's New York Times magazine on social contagion. It covers the Framingham study that I have mentioned in previous posts along with other studies that document how good as well as bad behaviors pass from friend to friend almost as if they were contagious viruses.

...behaviors may spread partly through the subconscious social signals that we pick up from those around us, which serve as cues to what is considered normal behavior. Scientists have been documenting this phenomenon; for example, experiments have shown that if a person is seated next to someone who’s eating more, he will eat more, too, unwittingly calibrating his sense of what constitutes a normal meal.
While emotional mirroring might be the most alluring idea about why behaviors spread, there are..
..two other possible explanations. One is “homophily,” the tendency of people to gravitate toward others who are like them. People who are gaining weight might well prefer to hang out with others who are also gaining weight, just as people who are happy might seek out others who are happy. The other possible explanation is that the shared environment — and not social contagion — might be causing the people of Framingham to change in groups. If a McDonald’s opens up in a Framingham neighborhood, it could cause a cluster of people living nearby to gain weight or become slightly happier (or sadder, depending on what they think about McDonald’s). The cluster of people would appear as though they are sharing a contagious form of behavior, but it would be an illusion.

How we change our decisions...

Resulaj et al develop a new model that accounts for how and when we change our mind after we make a decision. They do a series of experiments on subjects who were asked to move a handle to one of two positions dependent on a noisy visual stimulus. Analysis of the rare occasions where subjects changed their mind half way through selecting their answer shows that even after making a decision the brain continues to process the information it had gathered — information still in the processing pipeline— to either reverse or reaffirm its initial decision. Their new theory introduces the acts of vacillation and self correction into the decision-making process. The abstract outlines their basis idea:

A decision is a commitment to a proposition or plan of action based on evidence and the expected costs and benefits associated with the outcome. Progress in a variety of fields has led to a quantitative understanding of the mechanisms that evaluate evidence and reach a decision. Several formalisms propose that a representation of noisy evidence is evaluated against a criterion to produce a decision. Without additional evidence, however, these formalisms fail to explain why a decision-maker would change their mind. Here we extend a model, developed to account for both the timing and the accuracy of the initial decision, to explain subsequent changes of mind. Subjects made decisions about a noisy visual stimulus, which they indicated by moving a handle. Although they received no additional information after initiating their movement, their hand trajectories betrayed a change of mind in some trials. We propose that noisy evidence is accumulated over time until it reaches a criterion level, or bound, which determines the initial decision, and that the brain exploits information that is in the processing pipeline when the initial decision is made to subsequently either reverse or reaffirm the initial decision. The model explains both the frequency of changes of mind as well as their dependence on both task difficulty and whether the initial decision was accurate or erroneous. The theoretical and experimental findings advance the understanding of decision-making to the highly flexible and cognitive acts of vacillation and self-correction.

How chaos drives the brain.

I've been meaning to point out this excellent article in The New Scientist describing evidence that self-organised criticality is important brain function. It has links to a number of useful references.

Tuesday, September 15, 2009

Looming global disaster, anyone?

A panel of experts publishes a manifesto or guide in Science that is just the ticket for someone like myself who verges on clinical depression after every morning reading of the New York Times:

Energy, food, and water crises; climate disruption; declining fisheries; increasing ocean acidification; emerging diseases; and increasing antibiotic resistance are examples of serious, intertwined global-scale challenges spawned by the accelerating scale of human activity. They are outpacing the development of institutions to deal with them and their many interactive effects. The core of the problem is inducing cooperation in situations where individuals and nations will collectively gain if all cooperate, but each faces the temptation to take a free ride on the cooperation of others. The nation-state achieves cooperation by the exercise of sovereign power within its boundaries. The difficulty to date is that transnational institutions provide, at best, only partial solutions, and implementation of even these solutions can be undermined by internation competition and recalcitrance.


Figure - Interactive effects of global drivers on unwanted outcomes in the state of the world. Some outcomes also act as drivers of others (dashed arrows).

The major powers must be willing to enforce agreements, but legitimacy will depend on acceptance by numerous and diverse countries and by nongovernmental actors, such as civil society and business. This seems to be the basis for the greater success of the Montreal Protocol relative to the Kyoto Protocol. Strong backing by a majority for collective action, even though it may restrict individual freedoms, is necessary to institute and uphold an agreement. Formal sanctions are necessary to prevent cheating and are more likely to succeed where the backing is based on transparent, common norms. Agreements should not only be instruments of change but should establish processes for change, engaging a wide set of actors.

The institution of the nation-state has helped improve the well-being of many individuals, but at the cost of reduced global resilience. To address our common threats we need greater interaction among existing institutions, as well as new institutions, to help construct and maintain a global-scale social contract.

Our brain's fast response to morally objectionable statements.

Van Berkum et. al. make observations that go alongside the observations on moral conviction and religiosity mentioned in last friday's post.

How does the brain respond to statements that clash with a person's value system? We recorded event-related brain potentials while respondents from contrasting political-ethical backgrounds completed an attitude survey on drugs, medical ethics, social conduct, and other issues. Our results show that value-based disagreement is unlocked by language extremely rapidly, within 200 to 250 ms after the first word that indicates a clash with the reader's value system (e.g., "I think euthanasia is an acceptable/unacceptable…"). Furthermore, strong disagreement rapidly influences the ongoing analysis of meaning, which indicates that even very early processes in language comprehension are sensitive to a person's value system. Our results testify to rapid reciprocal links between neural systems for language and for valuation.

How much sleep do we need?

Recent work suggests a role for sleep in memory and/or synaptic plasticity. There is a large difference in how much sleep people need, ranging from less than 6 to more than 9 hours. Short sleepers are found in families, as are long sleepers, which suggests a genetic basis for sleep duration. He et al. now show that a mutation in a transcriptional factor, DEC2, is associated with short sleep in humans and mice. DEC2 is a transcription factor (protein that regulates gene function) involved in cell proliferation and differentiation, response to hypoxia, and circadian rhythms. Here is their abstract:

Sleep deprivation can impair human health and performance. Habitual total sleep time and homeostatic sleep response to sleep deprivation are quantitative traits in humans. Genetic loci for these traits have been identified in model organisms, but none of these potential animal models have a corresponding human genotype and phenotype. We have identified a mutation in a transcriptional repressor (hDEC2-P385R) that is associated with a human short sleep phenotype. Activity profiles and sleep recordings of transgenic mice carrying this mutation showed increased vigilance time and less sleep time than control mice in a zeitgeber time– and sleep deprivation–dependent manner. These mice represent a model of human sleep homeostasis that provides an opportunity to probe the effect of sleep on human physical and mental health.

Monday, September 14, 2009

Stimulate your waking memory with an electrical cap

A tiny oscillating electrical stimulation of which we are completely unaware (passed between electrodes on the forehead and jaw) can have the effect of enhancing memory consolidation during waking, an effect shown previously during sleep. The abstract of the open access PNAS article from Kirov et al.:

The application of transcranial slow oscillation stimulation (tSOS; 0.75 Hz) was previously shown to enhance widespread endogenous EEG slow oscillatory activity when applied during a sleep period characterized by emerging endogenous slow oscillatory activity. Processes of memory consolidation typically occurring during this state of sleep were also enhanced. Here, we show that the same tSOS applied in the waking brain also induced an increase in endogenous EEG slow oscillations (0.4–1.2 Hz), although in a topographically restricted fashion. Applied during wakefulness tSOS, additionally, resulted in a marked and widespread increase in EEG theta (4–8 Hz) activity. During wake, tSOS did not enhance consolidation of memories when applied after learning, but improved encoding of hippocampus-dependent memories when applied during learning. We conclude that the EEG frequency and related memory processes induced by tSOS critically depend on brain state. In response to tSOS during wakefulness the brain transposes stimulation by responding preferentially with theta oscillations and facilitated encoding.

Convergence of human and dog evolution, striving to please

Topál et al. perform some fascinating comparative studies that look in dogs for a curious error noted first by Piaget, who showed that 10-month-old humans infants will persist in looking for a toy in box A, where it has been placed several times, even after having been shown that it has been moved to box B, whereas 12-month-old infants do not. This phenomenon marks a developmental milestone in human infant cognition. Adult dogs, like human infants, will persevere in searching erroneously in box A because they regard the placement of the toy by a human experimenter as a social teaching event. By contrast, wolves rapidly learn correctly to search box B. They also observed that infants are able to generalize and thus still persevere when one experimenter places the toy in box A and a second then places the toy in box B. Dogs, however, display episodic learning, and a second experimenter reduces their searching choice to chance. Topál et al. suggest that sensitivity to human communicative signals stems from convergent social evolution of the Homo and the Canis genera.

MindBlog posts in the queue

I think I'll start passing along links to bits of work that I find interesting, but that are so far down my list of potential blog postings that they are unlikely to make it into a regular post. It seems a pity to let them disappear, because I'm aware that a few MindBlog readers with more specialized interests might be interested in some of them.

A study that suggests that increased gamma band (~40 Hz) event-related synchronization is related to, but not sufficient for, consciousness.

Clelland et al. show that synthesis of new nerve cells contributes to formation of spatial memories.

I Heard That Coming: Bendixen et al. show that event related potentials can signal the predictability of pattern in an upcoming a tone sequence.

Watching whales watching us. The evidence suggesting association between sonar and whale deaths is very convincing.

Scientists have now documented behaviors like tool use and cooperative hunting strategies among whales. Orcas, or killer whales, have been found to mourn their own dead. Just three years ago, researchers at Mount Sinai School of Medicine in New York discovered, in the brains of a number of whale species, highly specialized neurons that are linked to, among other things, the use of language and were once thought to be the exclusive property of humans and a few other primates. Indeed, marine biologists are now revealing not only the dizzying variety of vocalizations among a number of whale species but also complex societal structures and cultures.

Vorauer et al. on multiculturalism versus avoidance in influencing the tone of dominant/minority group interactions.

David Sloane Wilson and collaborators on how nice guys can finish last. From the summary in Nature:
Selfish individuals can profit from the altruism of others in their group, and can even exploit a group's resources so much that the resources become exhausted — an event known as the tragedy of the commons...Omar Eldakar, of the University of Arizona in Tucson, and his colleagues have now shown experimentally that aggressive mating in water striders (Aquarius remigis) can result in one such tragedy. Harassment of female water striders by males has previously been shown to drive away females, diminishing the mating success of all males in a group...The team built pools and manipulated the number of aggressive and nonaggressive males in each. They found that hyperaggressive males had greater mating success than those which were not aggressive within mixed pools. But as the number of hyperaggressive insects increased, the mating success of both types decreased.

Friday, September 11, 2009

Testosterone levels and long term career choices

From Sapienzaore et al., more on testosterone, gender, and risk aversion:

Women are generally more risk averse than men. We investigated whether between- and within-gender variation in financial risk aversion was accounted for by variation in salivary concentrations of testosterone and in markers of prenatal testosterone exposure in a sample of >500 MBA students. Higher levels of circulating testosterone were associated with lower risk aversion among women, but not among men. At comparably low concentrations of salivary testosterone, however, the gender difference in risk aversion disappeared, suggesting that testosterone has nonlinear effects on risk aversion regardless of gender. A similar relationship between risk aversion and testosterone was also found using markers of prenatal testosterone exposure. Finally, both testosterone levels and risk aversion predicted career choices after graduation: Individuals high in testosterone and low in risk aversion were more likely to choose risky careers in finance. These results suggest that testosterone has both organizational and activational effects on risk-sensitive financial decisions and long-term career choices.

Moral conviction and religiosity - different in the viscera

An interesting bit from Wisneski et al. :

Theory and research point to different ways moral conviction and religiosity connect to trust in political authorities to decide controversial issues of the day. Specifically, we predicted that stronger moral convictions would be associated with greater distrust in authorities such as the U.S. Supreme Court making the "right" decisions regarding controversial issues. Conversely, we predicted that stronger religiosity would be associated with greater trust in authorities. We tested these hypotheses using a survey of a nationally representative sample of Americans (N = 727) that assessed the degree to which people trusted the U.S. Supreme Court to rule on the legal status of physician-assisted suicide. Results indicated that greater religiosity was associated with greater trust in the U.S. Supreme Court to decide this issue, and that stronger moral convictions about physician-assisted suicide were associated with greater distrust in the U.S. Supreme Court to decide this issue. Also, the processes underlying religious trust and distrust based on moral convictions were more quick and visceral than slow and carefully considered.

The amygdala contributes to both aversive and appetitive arousal

Apparently the "scram!" and "go for it" emotions share some brain wiring. Shabel and Janak note that a large part of the amygdala, whose activation is usually associated with aversive emotions, is also activated during appetitive emotions. Thus there do not appear to be different circuits for the amygdala and autonomic nervous system arousal caused by positive versus aversive stimuli.

The amygdala is important for determining the emotional significance of environmental stimuli. However, the degree to which appetitive and aversive stimuli are processed by the same or different neuronal circuits within the amygdala remains unclear. Here we show that neuronal activity during the expression of classically conditioned appetitive and aversive emotional responses is more similar than expected by chance, despite the different sensory modalities of the eliciting stimuli. We also found that the activity of a large number of cells (> 43%) was correlated with blood pressure, a measure of emotional arousal. Together, our results suggest that a substantial proportion of neuronal circuits within the amygdala can contribute to both appetitive and aversive emotional arousal.

Thursday, September 10, 2009

Another reason I live in Wisconsin

I can certify that medical care in Florida (where I now spend the winter) and Texas (where I grew up) is medieval in comparison with Wisconsin. My experience is consonant with a great graphic from a New York Times article on health care costs and quality (click on graphic to enlarge it):

Why fear memories are hard to erase.

Gogolla et al. present evidence that fear memories are protected from erasure (extinction) by an matrix of compounds (chondroitin sulfate proteoglycans) outside of nerve cells in the amygdala, ie. in the extra-cellular matrix:

In adult animals, fear conditioning induces a permanent memory that is resilient to erasure by extinction. In contrast, during early postnatal development, extinction of conditioned fear leads to memory erasure, suggesting that fear memories are actively protected in adults. We show here that this protection is conferred by extracellular matrix chondroitin sulfate proteoglycans (CSPGs) in the amygdala. The organization of CSPGs into perineuronal nets (PNNs) coincided with the developmental switch in fear memory resilience. In adults, degradation of PNNs by chondroitinase ABC specifically rendered subsequently acquired fear memories susceptible to erasure. This result indicates that intact PNNs mediate the formation of erasure-resistant fear memories and identifies a molecular mechanism closing a postnatal critical period during which traumatic memories can be erased by extinction.
These results, together with previous experiments in the visual cortex on visual plasticity, suggest that maturation of the extracellular matrix could be a mechanism used by different brain circuits to change from a malleable to a more crystallized state during development. The presence of a high concentration of CSPGs in the perineuronal nets surrounding inhibitory neurons suggests that inhibitory circuits could play an important role in the developmental control of plasticity.

Lessons from Hell

In the New York Times Book Review Tom Vanderbilt discusses the new book by Rebecca Solnit on the communities (frequently amazingly altruistic) that arise in times of disaster, during which one might have expected the social fabric to rend.

Disasters, for Solnit, do not merely put us in view of apocalypse, but provide glimpses of utopia. They do not merely destroy, but create. “Disasters are extraordinarily generative,” she writes. As the prevailing order — which she elliptically characterizes as advanced global capitalism, full of anomie and isolation — collapses, another order takes shape: “In its place appears a reversion to improvised, collaborative, cooperative and local society.” These “disaster communities” represent something akin to the role William James claimed for “the utopian dreams” of social justice: “They help to break the general reign of hardness, and are slow leavens of a better order.”

A meta-narrative governing official response to the various disasters Solnit examines, from the industrial explosion that devastated Halifax in 1917 to the Mexico City earthquake of 1985 to New York on 9/11, is that cities wracked by disaster need to be protected from rampaging mobs, that government needs to suppress the panicked masses and save the day. But as Solnit illustrates, through an absorbing study of the academic subfield of “disaster sociology,” these Hobbesian (and Holly­wood) beliefs are seldom true.

First, official emergency responders are rarely the first people to respond to an emergency. Second, the central command-and-control model often misinterprets the reality on the ground. Third, the hero motif neglects the role of social capital, a soft-power variable that is played down in disaster management but which might help answer such interesting questions as why Cuba, in contrast to its neighbors (including the United States), responds so well to hurricanes, or why the 2003 New York City blackout was calm while its 1977 equivalent was not...Lastly, there’s the panic myth. A sociologist who set out to research panic in disasters found it was a “vanishingly rare phenomenon,” with cooperation and rational behavior the norm. More typically, panic comes from the top

Wednesday, September 09, 2009

Walter Kirn on performance enhancing drugs

Check out his account of his own experience.

The ability to stay on task, even the dullest, most numbing task, was Adderall’s first gift to me. It was also its first curse, because it encouraged me to take on work of an increasingly stupefying nature and do it well enough that I got more of it, until I was doing almost no other kind. I can see, though, how harried students might covet this power and why, according to some estimates, a quarter of undergraduates at certain colleges are availing themselves of such stimulants. They’re well aware of the dire economic news — big law firms instituting hiring freezes; whole industries, like publishing, imploding — and it’s natural that they would welcome any advantage in their quests to get the grades that will get them the jobs that will get them the insurance that will get them the medications to do the jobs.

I reached a point with Adderall that reminded me of a warning the United States Marine Corps is said to give its enemies: You can run, but you’ll only die tired...Or graduate tired, in the case of college students. And what’s so wrong with that? The course of a formal education is short but its consequences vast, so why not give it your spirit-crushing all, especially during a fiercely competitive age? “Simply because,” the parent in me says. He’s been there, this man. He’s weary, he’s spent and he just knows.

A cartoon...

Cartoon from the Sept. 7 New Yorker that really struck home for Deric (given that such a tiny fraction of what I am actually thinking ever makes it into this blog):

Some comic relief - talk about costume changes!

Tuesday, September 08, 2009

The amygdala as the neural source of personal space.

It turns out the amygdala, known to be important in our social interactions, may also be the core of regulating our personal space. (Americans and northern Europeans prefer a larger personal space than southern Europeans, while people with autism tend to unknowingly invade others' personal space.) Here is a a clip from a ScienceNow account of studies on a 42-year-old woman with a rare genetic disorder that destroyed both sides of her amygdala.

In early experiments, the scientists discovered that the woman, referred to as SM, couldn't spot fear in other people's faces; she also rated people as more trustworthy than an average person did. And she was extremely outgoing, "almost to the point where it isn't normal," says team member Daniel Kennedy. Even if she's only just met someone, he says, SM will invade their personal space--touching their arm as she talks or poking their stomach...In the new study, Kennedy and his colleagues more rigorously tested SM's sense of personal space. They compared her with 20 healthy subjects in a series of experiments. In one test, an experimenter slowly walked toward a subject until the subject felt uncomfortable and told the experimenter to stop. SM let experimenters get about twice as close as other subjects did, 0.34 meters versus 0.64 meters, the team reports online this week in Nature Neuroscience. She even felt fine standing nose to nose with an experimenter.
The findings in general support the idea that the amygdala functions as the brakes in social interactions. Here is a figure from the Nature Neuroscience report:


(a) Preference of S.M. (red) was the closest distance to the experimenter (black), among age-, gender-, race- and education-matched controls (purple, n = 5), as well as general comparison subjects (blue, n = 15). (b) S.M.'s mean preferred distance from the experimenter (image drawn to scale). (c) Control participants' mean preferred distance from the experimenter, excluding the three largest outliers (image drawn to scale).

The placebo effect is hard wired into the brain

It has been assumed that 'higher' brain structures linked to expectation are involved with sham treatments that can relieve pain, and natural opioid pathways are known to be important players. Now Eippert and colleagues have imaged the brains of volunteers given a sham ointment to relieve a mild burning pain. Half of them had been treated with naloxone, a chemical that blocks opioid signalling. They observed that placebo-related brain activity occurs in both the prefrontal cortex and more hard-wired areas, such as the amygdala, hypothalamus and parts of the brainstem. Here is more detail from their abstract:

Naloxone reduced both behavioral and neural placebo effects as well as placebo-induced responses in pain-modulatory cortical structures, such as the rostral anterior cingulate cortex (rACC). In a brainstem-specific analysis, we observeda similar naloxone modulation of placebo-induced responses in key structures of the descending pain control system, including the hypothalamus, the periaqueductal gray (PAG), and the rostral ventromedial medulla (RVM). Most importantly, naloxone abolished placebo-induced coupling between rACC and PAG, which predicted both neural and behavioral placebo effects as well as activation of the RVM. These findings show that opioidergic signaling in pain-modulating areas and the projections to downstream effectors of the descending pain control system are crucially important for placebo analgesia.

Brain changes correlating with bipolar disorder.

Three-dimensional model of the brain showing regions of increased volume in the insula, cerebellar vermis, and substantia nigra in individuals with genetic predisposition for bipolar disorder. The image has been reformatted in a style inspired by Vincent van Gogh, the most famous painter with bipolar disorder. For more information, see article by Kempton et al.

How did economists get it so wrong?

Krugman's article in the New York Times Sunday Magazine is really worth reading.

Monday, September 07, 2009

Monkey music

It is generally assumed that music, especially its emotional or affective components, has played an important role in human evolution. The music like component of language, prosody, is central in the "motherese" sounds made to calm human infants. Non-human primates, however, are almost completely indifferent to the sounds of human music. Now Chuck Snowdon here at Wisconsin has collaborated with musician David Teie in an interesting bit of work that demonstrates that cotton-top tamarin monkeys respond to 'tamarin music' synthesized from their affective vocalization sounds. Some interesting samples of the music are here, and here is the abstract of their work, which suggests that affective components in human music may have evolutionary origins in the structure of calls of non-human animals:

Theories of music evolution agree that human music has an affective influence on listeners. Tests of non-humans provided little evidence of preferences for human music. However, prosodic features of speech (‘motherese’) influence affective behaviour of non-verbal infants as well as domestic animals, suggesting that features of music can influence the behaviour of non-human species. We incorporated acoustical characteristics of tamarin affiliation vocalizations and tamarin threat vocalizations into corresponding pieces of music. We compared music composed for tamarins with that composed for humans. Tamarins were generally indifferent to playbacks of human music, but responded with increased arousal to tamarin threat vocalization based music, and with decreased activity and increased calm behaviour to tamarin affective vocalization based music. Affective components in human music may have evolutionary origins in the structure of calls of non-human animals. In addition, animal signals may have evolved to manage the behaviour of listeners by influencing their affective state.

Reducing anxiety caused by early life social isolation.

For rats (and humans) early social isolation causes anxiety-like behavior in adulthood. Work by Lukkes et al. now shows that an antagonist of a brain membrane corticotropin-releasing factor (CRF) receptor (delivered by a brain cannula) partially reverses this effect. Will we be seeing clinical trials of this approach in humans before long? The abstract:

Social isolation of rats during the early part of development increases social anxiety-like behavior in adulthood. Furthermore, early-life social isolation increases the levels of corticotropin-releasing factor (CRF) receptors in the serotonergic dorsal raphe nucleus (dRN) of adult rats. Interactions between serotonin and CRF systems are thought to mediate anxiety behavior. Therefore, we investigated the effects of CRF receptor antagonism within the dRN on social anxiety-like behavior after early-life social isolation. Male rats were reared in isolation or in groups from weaning until midadolescence, and rehoused in groups and allowed to develop into adulthood. Adult rats underwent surgery to implant a drug cannula into the dRN. After recovery from surgery and acclimation to the testing arena, rats were infused with vehicle or the CRF receptor antagonist D-Phe-CRF(12-41) (50 or 500 ng) into the dRN before a social interaction test. Isolation-reared rats pretreated with vehicle exhibited increased social anxiety-like behavior compared with rats reared in groups. Pretreatment of the dRN with D-Phe-CRF(12-41) significantly reduced social anxiety-like behaviors exhibited by isolation-reared rats. Overall, this study shows that early-life social stress results in heightened social anxiety-like behavior, which is reversed by CRF antagonism within the dRN. These data suggest that CRF receptor antagonists could provide a potential treatment of stress-related social anxiety.

Our brains have separate hard wired categories for living and non-living objects

Evolution apparently has selected for hard-wiring that separates neural categories for animals — towards which humans have important emotional responses — from those for non-living things. Here is the abstract from Mahon et al.

Distinct regions within the ventral visual pathway show neural specialization for nonliving and living stimuli (e.g., tools, houses versus animals, faces). The causes of these category preferences are widely debated. Using functional magnetic resonance imaging, we find that the same regions of the ventral stream that show category preferences for nonliving stimuli and animals in sighted adults show the same category preferences in adults who are blind since birth. Both blind and sighted participants had larger blood oxygen-level dependent (BOLD) responses inthe medial fusiform gyrus for nonliving stimuli compared to animal stimuli and differential BOLD responses in lateral occipital cortex for animal stimulicompared to nonliving stimuli. These findings demonstrate that the medial-to-lateral bias by conceptual domain in the ventral visual pathway does not require visual experience in order to develop and suggest the operation of innately determined domain-specific constraints on the organization of object knowledge.

Friday, September 04, 2009

Viva Happy Hour!

I have a daily happy hour - a ritual I have imbued with an almost religious aura, in which the single daily drink is sufficient to put me in "the zone." In spite of a literature that mostly says that a little booze is good for you, I still worry that I might be pickling more little gray cells than is desirable. Thus a recent little gem from the American Journal of Geriatric Psychiatry is reassuring. A meta-analysis combining many studies concludes that compared with abstainers, male drinkers reduced their risk for dementia by 45 percent, and women by 27 percent. This is consonant with evidence from other studies that moderate alcohol consumption can increase HDL, or “good cholesterol,” improve blood flow to the brain and decrease blood coagulation. You can check the article for the various caveats to the study.

Happiness and unhappiness in East and West

From Uchida et al.:

Cultural folk models of happiness and unhappiness are likely to have important bearings on social cognition and social behavior. At present, however, little is known about the nature of these models. Here, the authors systematically analyzed American and Japanese participants’ spontaneously produced descriptions of the two emotions and observed, as predicted, that whereas Americans associated positive hedonic experience of happiness with personal achievement, Japanese associated it with social harmony. Furthermore, Japanese were more likely than Americans to mention both social disruption and transcendental reappraisal as features of happiness. As also predicted, unlike happiness, descriptions of unhappiness included various culture-specific coping actions: Whereas Americans focused on externalizing behavior (e.g., anger and aggression), Japanese highlighted transcendental reappraisal and self-improvement.

Brief early exposure to high fat diet changes long term dietary habits

Yet another study of how early environment can cause virtually irreversible changes in later life habits. From Teegarden et al.

Overweight and obesity in the United States continues to grow at epidemic rates in large part due to the overconsumption of calorically-dense palatable foods. Identification of factors influencing long-term macronutrient preferences may elucidate points of prevention and behavioral modification. In our current study, we examined the adult macronutrient preferences of mice acutely exposed to a high fat diet during the third postnatal week. We hypothesized that the consumption of a high fat diet during early life would alter the programming of central pathways important in adult dietary preferences. As adults, the early-exposed mice displayed a significant preference for a diet high in fat compared to controls. This effect was not due to diet familiarity as mice exposed to a novel high carbohydrate diet during this same early period failed to show differences in macronutrient preferences as adults. The increased intake of high fat diet in early exposed mice was specific to dietary preferences as no changes were detected for total caloric intake or caloric efficiency. Mechanistically, mice exposed to a high fat diet during early life exhibited significant alterations in biochemical markers of dopamine signaling in the nucleus accumbens, including changes in levels of phospho–dopamine and cyclic AMP-regulated phosphoprotein, molecular weight 32 kDa (DARPP-32) threonine-75, ΔFosB, and cyclin-dependent kinase 5. These results support our hypothesis that even brief early life exposure to calorically-dense palatable diets alters long-term programming of central mechanisms important in dietary preferences and reward. These changes may underlie the passive overconsumption of high fat foods contributing to the increasing body mass in the western world.

Thursday, September 03, 2009

Weight as an embodyment of importance.

Jostman et al. do some interesting experiments that indicate that our abstract concept of importance is grounded in bodily experiences of weight. This is not a surprise, for weight is a metaphor for importance in many languages. People "weigh" the value of different options before making a decision, they "add weight" to place emphasis on important ideas, and their opinion "carries weight" if they fill an influential position. The experiments suggest that the link between weight and importance exists not only on a linguistic level, but also is an embodied cognition grounded in our bodily experiences of weight.

Participants provided judgments of importance while they held either a heavy or a light clipboard. Holding a heavy clipboard increased judgments of monetary value (Study 1) and made participants consider fair decision-making procedures to be more important (Study 2). It also caused more elaborate thinking, as indicated by higher consistency between related judgments (Study 3) and by greater polarization of agreement ratings for strong versus weak arguments (Study 4). In line with an embodied perspective on cognition, these findings suggest that, much as weight makes people invest more physical effort in dealing with concrete objects, it also makes people invest more cognitive effort in dealing with abstract issues.

Gene variants that correlate with both psychosis and creativity?

Even though a number of studies have discounted an association between creativity and madness, the persistence of the idea may have some basis in fact. Kéri has studied the relationship between a functional promoter polymorphism of the neuregulin 1 gene (SNP8NRG243177/rs6994992; C vs. T) and creativity in 200 healthy participants with high intellectual and academic performance who filled out a creative achievement questionnaire. (Neuregulin 1 - which affects neuronal development, synaptic plasticity, glutamatergic neurotransmission, and glial functioning - is one of the most actively investigated candidate genes for psychosis.) His results suggest that polymorphism of the promoter region TT, T/C, C/C is associated with creativity in people with high intellectual and academic performance. Intriguingly, the highest creative achievements and creative-thinking scores are found in people who carried the T/T genotype, which has been shown to be related to psychosis risk and altered prefrontal activation.

Fleeing from Facebook

Virginia Heffernan writes an interesting piece on the small but noticeable group who are fleeing from Facebook — some of them ostentatiously. Many apparently feel a sense of creeping disillusionment, and that Facebook is stalking them.

Is Facebook doomed to someday become an online ghost town, run by zombie users who never update their pages and packs of marketers picking at the corpses of social circles they once hoped to exploit? Sad, if so. Though maybe fated, like the demise of a college clique.

Wednesday, September 02, 2009

Woodland Peace

Predicting child temperament - genes, brain and behavior

Work from Schmidt et al. on correlations between frontal EEG asymmetry, variations in a dopamine receptor gene, and later temperament:

Gene-environment interactions involving exogenous environmental factors are known to shape behavior and personality development. Although gene-environment interactions involving endogenous environmental factors are hypothesized to play an equally important role, this conceptual approach has not been empirically applied in the study of early-developing temperament in humans. Here we report evidence for a gene-endoenvironment (i.e., resting frontal brain electroencephalogram, EEG, asymmetry) interaction in predicting child temperament. The dopamine D4 receptor (DRD4) gene (long allele vs. short allele) moderated the relation between resting frontal EEG asymmetry (left vs. right) at 9 months and temperament at 48 months. Children who exhibited left frontal EEG asymmetry at 9 months and who possessed the DRD4 long allele were significantly more soothable at 48 months than other children. Among children with right frontal EEG asymmetry at 9 months, those with the DRD4 long allele had significantly more difficulties focusing and sustaining attention at 48 months than those with the DRD4 short allele. Resting frontal EEG asymmetry did not influence temperament in the absence of the DRD4 long allele. We discuss how the interaction of genetic and endoenvironmental factors may confer risk and protection for different behavioral styles in children.

Multitasking - bad for the brain?

From the random samples section of the Aug. 28 issue of Science, reporting unsettling news from one of the first-ever studies of chronic multitaskers:

A team headed by psychologist Eyal Ophir compared 19 "heavy media multitaskers" (HMMs), identified by questionnaires on media use, with 22 "light media multitaskers" (LMMs). They tested how well the subjects could filter relevant information from the environment, filter relevant information in their memories, and quickly switch cognitive tasks. One filtering test, for example, required viewers to note changes in red rectangles while ignoring blue rectangles in the same pictures.

HMMs did worse than LMMs across the board. Surprisingly, says co-author Clifford Nass, "they're bad at every cognitive control task necessary for multitasking." Nass, a sociologist, says the study has "disturbing" implications in an age when more and more people are simultaneously working on computers, listening to music, surfing the Web, and texting or talking on a phone. Also troubling, he notes, is that "people who chronically multitask believe they're good at it." The findings are reported this week in the Proceedings of the National Academy of Sciences.

The team hopes to investigate whether multitasking really scrambles brains or whether people with poor filtering and attentional abilities are more attracted to it to begin with. Psychologist Anthony Wagner suspects that media multitasking offers instant rewards that reinforce "exploratory" behavior at the expense of the ability to concentrate on a particular task.

Five second touch sufficient to convey emotion.

Bakalar reports on work of Herenstein and others who show the sophistication and rapidity of our human ability to communicate emotions such as anger, fear, happiness, sadness, disgust, love, gratitude or sympathy with a brief touch.

Our sense of smell is binaral.

When different images are presented to each of our two eyes, or different sounds to each of our two ears, our perception usually switches back and forth between the two alternatives. Now Zhou and Chen have found that the same applies to two odors separately presented to each nostril. This binaral rivalry involves both cortical and peripheral (olfactory receptor) adaptations. (If one of two odors is first presented to a nostril, and then after a brief interval it is again presented to the nostril while a second odor of equal initial power is presented to the other nostril, the second odor is predominantly sensed.)

Tuesday, September 01, 2009

Get aroused and be stronger.

From Schmidt et al.:

Effort magnitude is commonly thought to reflect motivation, but little is known about the influence of emotional factors. Here, we manipulated the emotional state of subjects, via the presentation of pictures, before they exerted physical effort (squeezing a hand grip) to win money. After highly arousing pictures, subjects produced more force and reported lower effort sensation, regardless of monetary incentives. Functional neuroimaging revealed that emotional arousal, as indexed by postscan ratings, specifically correlated with bilateral activity in the ventrolateral prefrontal cortex. We suggest that this region, by driving the motor cortex, constitutes a brain pathway that allows emotional arousal to facilitate physical effort.

Figure - The emotional incentive force task. Successive screens displayed in every trial are shown from left to right, with durations in milliseconds. Emotional pictures that could be neutral or arousing (with positive or negative valence) were shown before physical effort. Effort was triggered by simultaneously showing the amount of money at stake, materialized as coin images (1 cent, 10 cents, or 1 {euro}), and a thermometer in which fluid level represented the force exerted on the hand grip. Subjects knew that the top of the thermometer corresponded to the monetary incentive, such that the more they squeezed the hand grip, the more money they would win. The last screen informed subjects about the cumulative total of monetary earnings.

Oxytocin Increases Envy and Schadenfreude (Gloating)

Work from Shamay-Tsoory et al. suggests that oxytocin plays a role in a wider range of social emotion-related behaviors than just positive pro-social behaviors.

Fifty-six participants participated in a double-blind, placebo-controlled, within-subject study. Following the administration of oxytocin or a placebo, participants played a game of chance with another (fake) participant who either won more money (envy manipulation), lost more money (schadenfreude manipulation), or won/lost equal amounts of money. In comparison with the placebo, oxytocin increased the envy ratings during unequal monetary gain conditions involving relative loss (when the participant gained less money than another player). Oxytocin also increased the ratings of gloating during relative gain conditions (when the participant gained more money than the other player). By contrast, oxytocin had no effect on the emotional ratings following equal monetary gains nor did it affect general mood ratings.

More on "Running helps your knees?" and exercise

I received an email from Dan Peterson, reacting to my comment in my Aug. 27 post that I "feel strange if I have missed a day of going to the university gym to swim, run, or do weights." He had just done a story on a study by Robin Kanarek of Tufts University on the endorphin-fueled addictive qualities of running/exercise in rats. Here is Peterson's blog.