Friday, September 28, 2012

Just so stories about the evolution of our minds.

I want to point to a very nicely done review in The New Yorker by Anthony Gottlieb, who notes a number of recent books dealing with evolutionary psychology, but mainly comments on “Homo Mysterious: Evolutionary Puzzles of Human Nature” (Oxford), a new book by David Barash, a professor of psychology and biology at the University of Washington, Seattle. The main point of critics is that most evolutionary theories purporting to explain our sexual or other behaviors as evolved adaptations to conditions faced by our paleolithic ancestors have no more validity than Rudyard Kipling's "just so" stories about how the camel got his hump or the rhinoceros his wrinkly folds of skin. One clip from the review:

A review of the methods of evolutionary psychology, published last summer in a biology journal, underlined a point so simple that its implications are easily missed. To confirm any story about how the mind has been shaped, you need (among other things) to determine how people today actually think and behave, and to test rival accounts of how these traits function. Once you have done that, you will, in effect, have finished the job of explaining how the mind works. What life was really like in the Stone Age no longer matters. It doesn’t make any practical difference exactly how our traits became established. All that matters is that they are there.

Thursday, September 27, 2012

Voting patterns: “I” value competence but “we” value social competence

(Chen et al. ask whether judgments of candidates' social competence—defined as the capacity for effective functioning in social interactions—are related to outcomes in an individualistic society (the United States) and a collectivist society (Taiwan). They replicate the earlier result that a judgment of competence does predict winners in the United States, as it does in Taiwan, and they find that judgments of social competence are also predictive, though only for elections in Taiwan. Their abstract:

This investigation distinguishes interpersonally oriented social competence from intrapersonally oriented competence. It examines the influence of voters' individualism and collectivism orientation in affecting the roles of these two dimensions in predicting electoral outcomes. Participants made judgments of personality traits based on inferences from faces of political candidates in the U.S. and Taiwan. Two social outcomes were examined: actual election results and voting support of the participants. With respect to actual electoral success, perceived competence is more important for the candidates in the U.S. than for those in Taiwan, whereas perceived social competence is more important for the candidates in Taiwan than for those in the U.S. With respect to subjective voting support, within cultural findings mirror those found cross-culturally. Competence is valued more among voters who are more individualistic, and social competence is valued more among voters who are more collectivistic. These results highlight important omissions in the social perception/judgment literature.


(excuse a techie note irrelevant to this post: I confirm the subscription of this blog to the Paperblog service under the username mdbownds)

Wednesday, September 26, 2012

Combat stress causes long term changes in brain connectivity.

Sobering results from Wingen et al.:

Prolonged stress can have long-lasting effects on cognition. Animal models suggest that deficits in executive functioning could result from alterations within the mesofrontal circuit. We investigated this hypothesis in soldiers before and after deployment to Afghanistan and a control group using functional and diffusion tensor imaging. Combat stress reduced midbrain activity and integrity, which was associated to compromised sustained attention. Long-term follow-up showed that the functional and structural changes had normalized within 1.5 y. In contrast, combat stress induced a persistent reduction in functional connectivity between the midbrain and prefrontal cortex. These results demonstrate that combat stress has adverse effects on the human mesofrontal circuit and suggests that these alterations are partially reversible.
Legend (click figure to enlarge) - Combat stress reduces functional connectivity of the midbrain with the lateral prefrontal cortex. The reduction from baseline to short-term follow-up is presented in blue. The persistent reduction from baseline to long-term follow-up at 1.5 y after military deployment is presented in green. The overlap between the short-term and long-term effects is presented in cyan.
A bit more expanded summary in their discussion:
These results show that the adverse effects of combat stress on sustained attention are related to functional and structural changes in the midbrain. These alterations normalize within 1.5 y in soldiers without psychiatric complaints, which may explain why long-term cognitive deficits following combat are mainly observed in soldiers with posttraumatic stress symptoms. In contrast to the reversible effects on the midbrain itself, its reduced interaction with the prefrontal cortex persists for at least 1.5 y. Taken together, these results suggest that the human brain can largely recover from the adverse effects of stress, supporting the view that neural plasticity in response to prolonged stress is adaptive. However, the results also reveal long-term changes within the mesofrontal network that may increase the vulnerability to subsequent stressors and lead to long-lasting cognitive deficits.

Tuesday, September 25, 2012

Male sex hormones alter the brain after exercise.

Numerous experiments have shown that exercise ability our ability to remember and think, and causes formation of new nerve cells. A collaboration that includes McEwen's Laboratory of Neuroendocrinology at Rockefeller now shows (in rats) that brain (not gonadal) production of the testosterone derivative dihydroxtestosterone (DHT) is required for this effect. The amount of exercise required is quite mild (McEwen: "the equivalent of jogging at a pace at which someone could speak (or squeak) to a companion."). In castrated rats blocking the action of testosterone levels that have been enhanced by exercise (by blocking testosterone receptors in the brain) also blocks the formation of new nerve cells. The chemical details are given by their abstract:

Mild exercise activates hippocampal neurons through the glutamatergic pathway and also promotes adult hippocampal neurogenesis (AHN). We hypothesized that such exercise could enhance local androgen synthesis and cause AHN because hippocampal steroid synthesis is facilitated by activated neurons via N-methyl-D-aspartate receptors. Here we addressed this question using a mild-intense treadmill running model that has been shown to be a potent AHN stimulator. A mass-spectrometric analysis demonstrated that hippocampal dihydrotestosterone increased significantly, whereas testosterone levels did not increase significantly after 2 wk of treadmill running in both orchidectomized (ORX) and sham castrated (Sham) male rats. Furthermore, analysis of mRNA expression for the two isoforms of 5α-reductases (srd5a1, srd5a2) and for androgen receptor (AR) revealed that both increased in the hippocampus after exercise, even in ORX rats. All rats were injected twice with 5′-bromo-2′deoxyuridine (50 mg/kg body weight, i.p.) on the day before training. Mild exercise significantly increased AHN in both ORX and Sham rats. Moreover, the increase of doublecortin or 5′-bromo-2′deoxyuridine/NeuN-positive cells in ORX rats was blocked by s.c. flutamide, an AR antagonist. It was also found that application of an estrogen receptor antagonist, tamoxifen, did not suppress exercise-induced AHN. These results support the hypothesis that, in male animals, mild exercise enhances hippocampal synthesis of dihydrotestosterone and increases AHN via androgenenic mediation.
In commenting on this work in the NYTimes, Gretchen Reynolds raises an interesting question for women:
But while those findings may be salutary for men who are active and fit, or planning to become so, they seem potentially troubling for those of us without testes. If DHT is necessary for neurogenesis after exercise and women produce far less of it than men, do women gain less brain benefit from exercise than men?

Monday, September 24, 2012

On being nothing...

The "Opinionater" feature of the New York Times has "Anxiety" as one of its topics inviting online essays. I wanted to pass on a piece submitted by Brian Jay Stanley that notes how at every stage of our lives we desire to be noticed and affirmed by others, and in the absence of notice can easily become anxious, feeling insignificant and insubstantial. His last two paragraphs are a treat:

Society is adroit at disillusioning newcomers, and many self-assured children grow up to be bitter adults. But bitterness, instead of a form of disillusionment, is really the refusal to give up your childhood illusions of importance. Ignored instead of welcomed by the world, you fault the world as blind and evil in order not to fault yourself as naïve. Bitterness is a child’s coddling narcissism within the context of an adult’s harsh life. Instead, I know that the world only tramples me as a street crowd does an earthworm — not out of malice or stupidity, but because no one sees it. Thus my pain is not to feel wrongly slighted, but to feel rightly slighted.
There must be a Copernican revolution of the self. Instead of pointlessly cursing the sun to go around me, my chance of contentment is learning to orbit, being the world’s audience instead of demanding the world be mine. If the world is a stage, then everyone’s an extra, acting minor roles in simultaneous scenes in which no one has the lead. With so much happening, society is poorly made to satisfy pride, but well made to satisfy interest, if we will only let go of our vanity and join the swirl of activity.

Friday, September 21, 2012

Signing beforehand increases honesty.

Here is a fascinating simple study by Shu et al. Simply signing a statement of honesty at the top rather the bottom of a form makes you more honest. They outline the problem:

The annual tax gap between actual and claimed taxes due in the United States amounts to roughly $345 billion. The Internal Revenue Service estimates more than half this amount is due to individuals misrepresenting their income and deductions (1). Insurance is another domain burdened by the staggering cost of individual dishonesty; the Coalition Against Insurance Fraud estimated that the overall magnitude of insurance fraud in the United States totaled $80 billion in 2006 (2). The problem with curbing dishonesty in behaviors such as filing tax returns, submitting insurance claims, claiming business expenses or reporting billable hours is that they primarily rely on self-monitoring in lieu of external policing.
Here is their abstract:
Many written forms required by businesses and governments rely on honest reporting. Proof of honest intent is typically provided through signature at the end of, e.g., tax returns or insurance policy forms. Still, people sometimes cheat to advance their financial self-interests—at great costs to society. We test an easy-to-implement method to discourage dishonesty: signing at the beginning rather than at the end of a self-report, thereby reversing the order of the current practice. Using laboratory and field experiments, we find that signing before, rather than after, the opportunity to cheat makes ethics salient when they are needed most and significantly reduces dishonesty.
The experimental design used several different measures of cheating: self-reported earnings (income) on a math puzzles task wherein university participants could cheat for financial gain, self reported travel expenses to the laboratory (deductions) claimed on a tax return form on research earnings. Another experiment was done in the field with an insurance company in the southeastern United States asking some of their existing customers to report their odometer reading. They examined the effect of requiring the signature at the top of the form, the bottom, or the control of requiring no signature.

A personal history.

I thought I would mention that in response to several requests from friends and family I have now posted a personal history on my dericbownds.net website at http://www.dericbownds.net/DericHistory.html.

Thursday, September 20, 2012

Distinct prefrontal areas regulating cognitive control and value decisions.

A massive study involving workers at five different universities has utilized a dataset on brain lesions accumulated over many decades to reveal two distinct functional-anatomical networks within the prefrontal cortex (PFC), one associated with cognitive control and the other associated with value-based decision-making. They used lesion-symptom mapping in 344 participants who were assessed by using a large battery of standardized neuropsychological tasks. Of these participants, 165 had damage in the frontal lobes that included sectors of the PFC, supplementary motor area (SMA), or premotor cortex (PM). Here is their abstract, followed by some details:

A considerable body of previous research on the prefrontal cortex (PFC) has helped characterize the regional specificity of various cognitive functions, such as cognitive control and decision making. Here we provide definitive findings on this topic, using a neuropsychological approach that takes advantage of a unique dataset accrued over several decades. We applied voxel-based lesion-symptom mapping in 344 individuals with focal lesions (165 involving the PFC) who had been tested on a comprehensive battery of neuropsychological tasks. Two distinct functional-anatomical networks were revealed within the PFC: one associated with cognitive control (response inhibition, conflict monitoring, and switching), which included the dorsolateral prefrontal cortex and anterior cingulate cortex and a second associated with value-based decision-making, which included the orbitofrontal, ventromedial, and frontopolar cortex. Furthermore, cognitive control tasks shared a common performance factor related to set shifting that was linked to the rostral anterior cingulate cortex. By contrast, regions in the ventral PFC were required for decision-making. These findings provide detailed causal evidence for a remarkable functional-anatomical specificity in the human PFC.
Here is a description of the array of tests used (edited to simplify):
The four cognitive control tasks were as follows: the Trail-Making Test (TMT), a measure of executive response switching; the Perseverative Errors score from the Wisconsin Card Sorting Test (WCST), which measures impairments in set switching; the Color-Word Interference score from the Stroop Test (STROOP), a measure of response inhibition; and the Number of Words score from the Controlled Oral Word Association Test (COWA), which measures verbal fluency, divergent thinking, and response creativity. As an index of value-based decision-making and reward learning, we used the Net Score (advantageous minus disadvantageous choices) from the Iowa Gambling Task (IGT). All these tasks have been extensively used and well standardized, and they have been shown to detect impairments reliably in clinical populations such as ours. As expected, the cognitive control-related tasks were all weakly, but positively intercorrelated, whereas their correlation with the IGT was generally lower, a pattern that remained even after the covariates were statistically removed from the data.
And here is a summary graphic:


Results from the lesion overlap analysis of different tests of cognitive control and value-based decision making.

Wednesday, September 19, 2012

Motivation influences how time flies when you’re having fun.

Numerous studies have shown that a positive state, relative to a negative state, makes time appear to pass more quickly and causes assessments of elapsed time to be shorter. Gable and Pool examine how the degree of motivation - as distinguished from positive or negative valence (as in approach versus withdrawal) - influences subjective time:

Time flies when you’re having fun, but what is it about pleasant experiences that makes time seem to go by faster? In the experiments reported here, we tested the proposal that approach motivation causes perceptual shortening of time during pleasant experiences. A first experiment showed that, relative to a neutral state or a positive state with low approach motivation, a positive state with high approach motivation shortened perceptions of time. Also, individual differences in approach motivation predicted shorter perceptions of time. In a second experiment we manipulated approach motivation independently of the affective state and showed that increasing approach motivation caused time to be perceived as passing more quickly. Finally we showed that positive approach motivation, as opposed to arousal, shortens perception of time by comparing a highly arousing positive state with a highly arousing negative state. Shortening of time perception in appetitive states may prolong approach-motivated behavior and increase the likelihood of acquiring appetitive objects or goals.

Tuesday, September 18, 2012

Neural signature of affiliative emotions.

Moll et al. do an interesting study to experimentally disentangle affiliative experience from general emotional valence, by demonstrating that brain areas distinctive to expression of affiliative (bonding) emotions engage an ensemble of basal forebrain structures that is conserved in mammals, and can be distinguished from areas reflecting the positive or negative emotional valence that accompanies the subjective affiliative experience. Here is their abstract, following by one of the illustrations from the paper:

Comparative studies have established that a number of structures within the rostromedial basal forebrain are critical for affiliative behaviors and social attachment. Lesion and neuroimaging studies concur with the importance of these regions for attachment and the experience of affiliation in humans as well. Yet it remains obscure whether the neural bases of affiliative experiences can be differentiated from the emotional valence with which they are inextricably associated at the experiential level. Here we show, using functional MRI, that kinship-related social scenarios evocative of affiliative emotion induce septal–preoptic–anterior hypothalamic activity that cannot be explained by positive or negative emotional valence alone. Our findings suggest that a phylogenetically conserved ensemble of basal forebrain structures, especially the septohypothalamic area, may play a key role in enabling human affiliative emotion. Our finding of a neural signature of human affiliative experience bears direct implications for the neurobiological mechanisms underpinning impaired affiliative experiences and behaviors in neuropsychiatric conditions.

Figure Legend - Activation of the septal/preoptic-anterior hypothalamic and medial FPC, predicted a priori, as well as in the left posterior superior temporal sulcus region (data not shown) and precuneus (Prec), observed in the affiliative versus nonaffiliative contrast.

Figure Legend - Brain regions associated with positive versus negative conditions (red-yellow) and negative versus positive contrasts (blue-green). Activation of the ventral striatum (VStr) and medial orbitofrontal cortex (medOFC; BA11/32) was observed in the positive versus negative contrast. For the negative versus positive contrast, activation of dorsomedial prefrontal cortex (dmPFC; BA 8/9) and lateral frontal cortex, including the lateral orbitofrontal cortex and inferior frontal gyrus (latFC), as well as the adjoining anterior insula (antIns) was observed (BA 45/47/48).

Monday, September 17, 2012

Do implicit attitudes predict actual voting behavior?

How can psychologists and pollsters predict the voting behavior of undecided voters? Is there is any hope for us Obama supporters who worry about the effectiveness of the clever framing of the conservative marketing aimed at undecided voters that pushes emotional buttons with complete disregard for rationality or facts? Friese et al. show that explicit attitudes predict voting behavior better than implicit attitudes for both decided and undecided voters, while implicit attitudes predict voting behavior better for decided than undecided voters. While this is not to say that explicit attitudes can't also be based on irrationality, it does argue against the power of implicit attitudes of which the voter is unaware. Here is their abstract:

The prediction of voting behavior of undecided voters poses a challenge to psychologists and pollsters. Recently, researchers argued that implicit attitudes would predict voting behavior particularly for undecided voters whereas explicit attitudes would predict voting behavior particularly for decided voters. We tested this assumption in two studies in two countries with distinct political systems in the context of real political elections. Results revealed that (a) explicit attitudes predicted voting behavior better than implicit attitudes for both decided and undecided voters, and (b) implicit attitudes predicted voting behavior better for decided than undecided voters. We propose that greater elaboration of attitudes produces stronger convergence between implicit and explicit attitudes resulting in better predictive validity of both, and less incremental validity of implicit over explicit attitudes for the prediction of voting behavior. However, greater incremental predictive validity of implicit over explicit attitudes may be associated with less elaboration.

Friday, September 14, 2012

Psychological distance enhances conformity to group norms.

In yet another of one of those studies that give what would appear to be a generally applicable result, but is based on experiments carried out on two rather selective population represented by undergraduate psychology students at a U.S. college (UC-Davis, and NYU), Ledgerwood and Callahan demonstrate that psychological distance can enhance conformity to group norms, contra the usual association of the distanced or abstracted thinker (think Spock or Obama) with reasoned opinions that resist group pressure.

In the first study noted in their abstract below. they manipulated the temporal distance of a policy by varying whether it would be implemented in the near or distant future. They then provided participants with information about the majority opinion before asking them to report their own attitudes toward the policy. (The study's 67 participants (72% female) completed a study described as an online student opinion survey. All participants read an article excerpt (ostensibly from an online campus newsletter), which stated that the Davis City Council was considering whether to approve a proposal that would require all bicycles - the primary mode of student transportation in Davis - to use rear bicycle lights for nighttime travel.) Participants tended to conform to group opinion when the policy would be implemented in the relatively distant future, expressing more favorable attitudes when the group favored the policy than when the group opposed it.

The second study, a bit more complicated, asked students who had been primed in a diversionary task that required thinking in either concrete or abstract terms, to vote on a previously defined affirmation action issue. They did this by privately placing a number of 'yes' or 'no' tokens proportional to how strongly they felt in boxes that already contained tokens placed by the group of previous voters (actually the experimenters). Participants conformed to the group norm after they had been led to think abstractly, voting more strongly in favor of affirmative action when the group seemed to support it rather than oppose it.

Here is the abstract:

Intuition suggests that a distanced or abstract thinker should be immune to social influence, and on its surface, the current literature could seem to support this view. The present research builds on recent theorizing to suggest a different possibility. Drawing on the notion that psychological distance regulates the extent to which evaluations incorporate context-specific or context-independent information, we suggest that psychological distance should actually increase susceptibility to sources of social influence that tend to be consistently encountered across contexts, such as group norms. Consistent with this hypothesis, two studies showed that psychological distance and abstraction increased conformity to group opinion and that this effect persisted in a novel voting-booth paradigm in which participants believed their voting behavior was both anonymous and consequential. We discuss implications of these findings for understanding the social side of abstraction as well as the conditions under which different types of social influence are likely to be most influential.

Thursday, September 13, 2012

Zero effect of caloric restriction on lifespan

I would be very surprised if there were any blog readers who are unaware of this material, released two weeks ago with saturation coverage by the popular press, but because human aging has been a continuous topic in this blog I thought I should pass on reference to the results of an exhaustive study by Mattison et al. that has failed to confirm an effect of dietary caloric restriction on longevity in rhesus monkeys, even though some beneficial health effects are noted. This takes the edge off my motivation to do occasional fits of dieting with the assurance that this might influence how long this 70-year old body continues to hang around.

Calorie restriction (CR), a reduction of 10–40% in intake of a nutritious diet, is often reported as the most robust non-genetic mechanism to extend lifespan and healthspan. CR is frequently used as a tool to understand mechanisms behind ageing and age-associated diseases. In addition to and independently of increasing lifespan, CR has been reported to delay or prevent the occurrence of many chronic diseases in a variety of animals. Beneficial effects of CR on outcomes such as immune function, motor coordination and resistance to sarcopenia in rhesus monkeys have recently been reported. We report here that a CR regimen implemented in young and older age rhesus monkeys at the National Institute on Aging (NIA) has not improved survival outcomes. Our findings contrast with an ongoing study at the Wisconsin National Primate Research Center (WNPRC), which reported improved survival associated with 30% CR initiated in adult rhesus monkeys (7–14 years) and a preliminary report with a small number of CR monkeys. Over the years, both NIA and WNPRC have extensively documented beneficial health effects of CR in these two apparently parallel studies. The implications of the WNPRC findings were important as they extended CR findings beyond the laboratory rodent and to a long-lived primate. Our study suggests a separation between health effects, morbidity and mortality, and similar to what has been shown in rodents, study design, husbandry and diet composition may strongly affect the life-prolonging effect of CR in a long-lived nonhuman primate.

Wednesday, September 12, 2012

Cognitive load disrupts implicit theory of mind processing.

I'm passing this on because I was totally unaware of the implicit theory of mind (TOM) system that is explained in these clips from the article by Schneider et al.. They test whether this implicit TOM system is independent of domain-general, capacity-limited, cognitive resources (e.g., working memory.) First the abstract:

Eye movements in Sally-Anne false-belief tasks appear to reflect the ability to implicitly monitor the mental states of other individuals (theory of mind, or ToM). It has recently been proposed that an early-developing, efficient, and automatically operating ToM system subserves this ability. Surprisingly absent from the literature, however, is an empirical test of the influence of domain-general executive processing resources on this implicit ToM system. In the study reported here, a dual-task method was employed to investigate the impact of executive load on eye movements in an implicit Sally-Anne false-belief task. Under no-load conditions, adult participants displayed eye movement behavior consistent with implicit belief processing, whereas evidence for belief processing was absent for participants under cognitive load. These findings indicate that the cognitive system responsible for implicitly tracking beliefs draws at least minimally on executive processing resources. Thus, even the most low-level processing of beliefs appears to reflect a capacity-limited operation.
And here, slightly edited, is some essential background material from their introduction:
A key paradigm for assessing ToM abilities is the Sally-Anne false-belief task: In still images, movies, or “live” performance (with puppets, actors, or both), “Sally” sees an object (e.g., a ball) being placed in a container. Sally then leaves the room. Next, “Anne” hides the object in a different container. When Sally returns to the room, participants are required to identify the location where they think Sally will first look for the object. To succeed at the task, participants must select (e.g., point to) the location that is consistent with Sally’s belief, as opposed to the actual, known location of the object.
Passing this explicit Sally-Anne task is thought to reflect a developmental milestone, which is typically achieved by the age of 4 years. Such findings suggest that children understand other people’s beliefs by this age. However, recent research using a variety of implicit ToM tasks suggests that children as young as 7 months may be able to register other individuals’ beliefs. For example, monitoring of eye movement behavior in free-viewing false-belief scenarios has demonstrated that 2-year-olds preferentially look toward the location at which the actor believes the ball to be.
Do humans fail to understand other individuals’ internal mental states until the age of 4, or is this fundamental ability already present during the 1st year of life? To accommodate these seemingly incongruent findings, Apperly and Butterfill proposed that throughout the life span, ToM is subserved by two distinct systems. According to this framework, an earlier-developing system, which operates implicitly and is independent of the development of language and executive function (e.g., working memory), is responsible for efficient monitoring of belief-like states. A later-developing system, which is dependent on domain-general cognitive functions (e.g., executive function), allows conscious (explicit) ToM inferences. Evidence supporting this framework includes a dissociation found in adults with Asperger’s syndrome, who can pass explicit false-belief tasks but do not display eye movement patterns consistent with implicit ToM in a Sally-Anne free-viewing paradigm.

Tuesday, September 11, 2012

Why the sex gap in affective disorders?

Here is an abstract from Hu et al., which I pass on to you even though it is rather technical, that shows that an increase in negative affective behavior in stressed female versus male mice that correlates with a decrease (vs increase in males) in their hippocampal NO (nitric oxide) levels. If the hippocampal NO levels are equalized in male and females, their affective behaviors become similar.

Mechanisms underlying the female preponderance in affective disorders are poorly understood. Here we show that hippocampal nitric oxide (NO) plays a role in the sex difference of depression-like behaviors in rodents. Female mice had substantially lower NO production in the hippocampus and were significantly more likely to display negative affective behaviors than their male littermates. Eliminating the difference in the basal hippocampal NO level between male and female mice mended the sex gap of affective behaviors. Estradiol exerted a positive control on hippocampal NO production via estrogen receptor-β–mediated neuronal NO synthase expression. Thus, low estrogen in the female hippocampus accounts for lower local NO than in the male hippocampus. Although estrogen has important significance in modulating affective behaviors, it is not estrogen but NO in the hippocampus that mediates the sex difference of affective behaviors directly, because hippocampal NO was necessary for the behavioral effects of estradiol, and NO was an independent factor in modulating behaviors. Stress promoted hippocampal NO production in males because of glucocorticoid release, thus leading to local NO excess. In contrast, stress suppressed NO production in females because of decreased estrogen, thereby resulting in hippocampal NO shortage. Whereas activating cAMP response element binding protein (CREB) rescued the depression-like effects of the intrahippocampal NO donor diethylenetriamine/nitric oxide adduct (DETA/NONOate), inactivating CREB abolished the antidepressant-like effects of the intrahippocampal NO donor DETA/NONOate. Our findings suggest a molecular mechanism underlying the sex difference of affective behaviors.

Monday, September 10, 2012

Investing in Karma - When Wanting Promotes Helping

An interesting piece from Converse et al. provides reliable evidence that people do good deeds when they want something beyond their control. This suggests that they act in accord with a karmic tenet rooted in immanent justice (but doesn't necessarily imply pervasive explicit belief in karma.) Here is the abstract slightly edited:

People often face outcomes of important events that are beyond their personal control, such as when they wait for an acceptance letter, job offer, or medical test results. We suggest that when wanting and uncertainty are high and personal control is lacking, people may be more likely to help others, as if they can encourage fate’s favor by doing good deeds proactively. Four experiments support this karmic-investment hypothesis. The first two experiments show that when people want an outcome over which they have little control, their donations of time and money increase, but their participation in other rewarding activities does not. A third experiment shows that, in addition, at a job fair, job seekers who feel the process is outside (vs. within) their control make more generous pledges to charities. A final experiment shows that karmic investments increase optimism about a desired outcome. We conclude by discussing the role of personal control and magical beliefs in this phenomenon.
Some clips from their discussion:
Past research has found that people automatically anticipate negative outcomes following behaviors that tempt fate, and that people associate positive outcomes with virtuous behaviors. Thus, people may develop a basic good-behavior—good-outcome association, such that hoping for good outcomes activates the cognitive script to do good deeds...whether based on explicit or implicit belief, some version of a karmic belief system must be at least momentarily activated when people face important, uncontrollable outcomes...our findings fit with the notion that people turn to external sources of control, such as gods and governments, when internal control is lacking, and may even turn to apparently magical systems when necessary...rather than increasing selfishness, wanting can increase helping...people may not only pursue reciprocal exchanges interpersonally, but may also attempt to bargain with the universe.

Friday, September 07, 2012

Alcohol and group formation.

Sayette et al. do what looks like a thorough piece of work, but I also have a "Duh...tell us something else we didn't already know" kind of reaction. This is why evidence of human grape fermentation is found very early in the archeological record, and probably extends beyond it.

We integrated research on emotion and on small groups to address a fundamental and enduring question facing alcohol researchers: What are the specific mechanisms that underlie the reinforcing effects of drinking? In one of the largest alcohol-administration studies yet conducted, we employed a novel group-formation paradigm to evaluate the socioemotional effects of alcohol. Seven hundred twenty social drinkers (360 male, 360 female) were assembled into groups of 3 unacquainted persons each and given a moderate dose of an alcoholic, placebo, or control beverage, which they consumed over 36 min. These groups’ social interactions were video recorded, and the duration and sequence of interaction partners’ facial and speech behaviors were systematically coded (e.g., using the Facial Action Coding System). Alcohol consumption enhanced individual- and group-level behaviors associated with positive affect, reduced individual-level behaviors associated with negative affect, and elevated self-reported bonding. Our results indicate that alcohol facilitates bonding during group formation. Assessing nonverbal responses in social contexts offers new directions for evaluating the effects of alcohol.

Thursday, September 06, 2012

Where thinking about thinking happens in the brain.

We evaluate and alter the cognitive functions we perform, as when we revise or edit our writing or speaking. This monitoring and controlling is usually referred to as metacognition. Middlebrooks and Sommer have recently done an elegant study of metacognition in Macaque monkeys, using a simple betting paradigm:

Humans are metacognitive: they monitor and control their cognition. Our hypothesis was that neuronal correlates of metacognition reside in the same brain areas responsible for cognition, including frontal cortex. Recent work demonstrated that nonhuman primates are capable of metacognition, so we recorded from single neurons in the frontal eye field, dorsolateral prefrontal cortex, and supplementary eye field of monkeys (Macaca mulatta) that performed a metacognitive visual-oculomotor task. The animals made a decision and reported it with a saccade, but received no immediate reward or feedback. Instead, they had to monitor their decision and bet whether it was correct. Activity was correlated with decisions and bets in all three brain areas, but putative metacognitive activity that linked decisions to appropriate bets occurred exclusively in the SEF. Our results offer a survey of neuronal correlates of metacognition and implicate the SEF in linking cognitive functions over short periods of time.
Highlight points:
-Monkeys made decisions and wagered on their performance in a metacognitive task
-Single neurons were recorded in three frontal cortical region
-Only supplementary eye field (SEF) neuronal activity correlated with metacognition
-The SEF metacognitive signal provided a temporal “bridge” between decision and bet

Wednesday, September 05, 2012

The unimaginable complexity of our evolved human systems.

In the face of all the current hubris about redesigning and engineering humans using modern genetic and biochemical tools, trying to reverse engineer brain systems that were never engineered in the first place, Randolph Nesse offers a very therapeutic essay. Here is a slightly edited version:

The products of natural selection are … not merely complicated in the way that machines are complicated, they are organically complex in ways that are fundamentally different from any product of design. This makes them difficult for human minds to fully describe or comprehend. So, we use that grand human gambit for understanding, a metaphor, in this case, the body as machine…it easy to portray the systems that mediate cell division, immune responses, glucose regulation, and all the rest, using boxes for the parts, and arrows to indicate causes what. Such diagrams summarize important information in ways we can grasp. .. But, they fundamentally misrepresent the nature of organic complexity.
Thinking about the body as a machine was a grand advance in the 16th century, when it offered an alternative to vitalism and vague notions of the life force. Now it is outmoded. It distorts our view of biological systems by fostering thinking about them as simpler and more sensibly "designed" than they are. Experts know better. They recognize that the mechanisms that regulate blood clotting are represented only crudely by the neat diagrams medical students memorize; most molecules in the clotting system interact with many others. Experts on the amygdala know that it does not have one or two functions, it has many, and they are mediated by scores of pathways to other brain loci. Serotonin exists not mainly to regulate mood and anxiety, it is essential to vascular tone, intestinal motility, and bone deposition. Leptin is not mainly a fat hormone, it has many functions, serving different ones at different time, even in the same cell. The reality of organic systems is vastly untidy. If only their parts were all distinct, with specific functions for each! Alas, they are not like machines. Our human minds have as little intuitive feeling for organic complexity as they do for quantum physics.
Recent progress in genetics confronts the problem. Naming genes according to postulated functions is as natural as defining chairs and boats by their functions. If each gene were a box on a blueprint labeled with its specific function, biology would be so much more tractable! However, it is increasingly clear that most traits are influenced by many genes, and most genes influence many traits. For instance, about 80% of the variation in human height is accounted for by genetic variation. It would seem straightforward to find the responsible genes. But looking for them has revealed that the 180 loci with the largest effects together account for only about 10% of the phenotypic variation. Recent findings in medical genetics are more discouraging. Just a decade ago, hope was high that we would soon find the variations that account for highly heritable diseases, such as schizophrenia and autism. But scanning the entire genome has revealed that there are no common alleles with large effects on these diseases. Some say we should have known. Natural selection would, after all, tend to eliminate alleles that cause disease. But, thinking about the body as a machine aroused unrealistic hopes.
The grand vision for some neuroscientists is to trace every molecule and pathway to characterize all circuits in order to understand how the brain works. Molecules, loci, and pathways do serve differentiated functions, this is real knowledge with great importance for human health. But, understanding how the brain works by drawing a diagram that describes all the components and their connections and functions is a dream that may be unfulfillable. The problem is not merely fitting a million items on a page, the problem is that no such diagram can adequately describe the structure of organic systems. They are products of miniscule changes, from diverse mutations, migration, drift, and selection, which develop into systems with incompletely differentiated parts and incomprehensible interconnections, that, nonetheless, work very well indeed. Trying to reverse engineer brain systems focuses important attention on functional significance, but it inherently limited, because brain systems were never engineered in the first place.
If bodies are not like machines, what are they like? They are more like Darwin's "tangled bank" with its "elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner." Lovely. But, can an ecological metaphor replace the metaphor of body as machine? Not likely. Perhaps someday understanding how natural selection shapes organic complexity will be so widely and deeply understood that scientists will be able to say "A body is like…a living body," and everyone will know exactly what that means. 

Tuesday, September 04, 2012

Mapping discrete and dimensional emotions onto the brain.

Here I am passing on the abstract and one summary figure from a useful recent review article by Stephan Hamann:

A longstanding controversy in the field of emotion research has concerned whether emotions are better conceptualized in terms of discrete categories, such as fear and anger, or underlying dimensions, such as arousal and valence. In the domain of neuroimaging studies of emotion, the debate has centered on whether neuroimaging findings support characteristic and discriminable neural signatures for basic emotions or whether they favor competing dimensional and psychological construction accounts. This review highlights recent neuroimaging findings in this controversy, assesses what they have contributed to this debate, and offers some preliminary conclusions. Namely, although neuroimaging studies have identified consistent neural correlates associated with basic emotions and other emotion models, they have ruled out simple one-to-one mappings between emotions and brain regions, pointing to the need for more complex, network-based representations of emotion.

Figure - Levels of mapping between emotion models and the brain. The left panel illustrates the most commonly proposed one-to-one mappings between elements of emotion theories and individual brain regions. For example, amygdala activation typically correlates with emotional arousal, whereas activation in the orbitofrontal cortex correlates with emotional valence. As noted in the text, these one-to-one mappings run afoul of numerous experimental findings that show that, for example, fear consistently activates regions other than the amygdala, and the amygdala in turn is associated with several emotion processes. Such difficulties with one-to-one mappings have motivated a shift to more complex interrelationships, such as functional networks. For example, in the right panel, network mappings may involve individual brain regions (small rectangles) participating in networks that carry out the processing mediating different emotions. An individual region, such as the amygdala (red rectangle) can participate in multiple networks and that region's role can be modulated according to the currently active network configuration. These network dynamics have important implications for evaluating the neuroimaging evidence for different emotion theories.

Monday, September 03, 2012

How childhood musical training shapes the adult brain.

From Skoe and Kraus:

Playing a musical instrument changes the anatomy and function of the brain. But do these changes persist after music training stops? We probed this question by measuring auditory brainstem responses in a cohort of healthy young human adults with varying amounts of past musical training. We show that adults who received formal music instruction as children have more robust brainstem responses to sound than peers who never participated in music lessons and that the magnitude of the response correlates with how recently training ceased. Our results suggest that neural changes accompanying musical training during childhood are retained in adulthood. These findings advance our understanding of long-term neuroplasticity and have general implications for the development of effective auditory training programs.