Friday, April 10, 2009

Sites for abstract versus concrete actions in frontal lobes.

By observing behavioral deficits of lesion patients Badre et al. find that there is a hierarchical organization of cognitive control, with rostral (towards top of head) areas of the frontal lobes being required for decisions about more abstract actions and lower caudal areas (towards spinal column or tail) being required for decisions about more concrete actions.
Cognitive control permits us to make decisions about abstract actions, such as whether to e-mail versus call a friend, and to select the concrete motor programs required to produce those actions, based on our goals and knowledge. The frontal lobes are necessary for cognitive control at all levels of abstraction. Recent neuroimaging data have motivated the hypothesis that the frontal lobes are organized hierarchically, such that control is supported in progressively caudal regions as decisions are made at more concrete levels of action. We found that frontal damage impaired action decisions at a level of abstraction that was dependent on lesion location (rostral lesions affected more abstract tasks, whereas caudal lesions affected more concrete tasks), in addition to impairing tasks requiring more, but not less, abstract action control. Moreover, two adjacent regions were distinguished on the basis of the level of control, consistent with previous functional magnetic resonance imaging results. These results provide direct evidence for a rostro-caudal hierarchical organization of the frontal lobes.

Thursday, April 09, 2009

Neural mechanism of first impressions.

From Schiller et al:
Evaluating social others requires processing complex information. Nevertheless, we can rapidly form an opinion of an individual during an initial encounter. Moreover, people can vary in these opinions, even though the same information is provided. We investigated the brain mechanisms that give rise to the impressions that are formed on meeting a new person. Neuroimaging revealed that responses in the amygdala and the posterior cingulate cortex (PCC) were stronger while encoding social information that was consistent, relative to inconsistent, with subsequent evaluations. In addition, these responses scaled parametrically with the strength of evaluations. These findings provide evidence for encoding differences on the basis of subsequent evaluations, suggesting that the amygdala and PCC are important for forming first impressions.

Figure. (Click to enlarge) a - Functional regions of interest (ROIs) were identified by contrasting faces with person-descriptive sentences versus face-alone presentations. The dmPFC and left amygdala are denoted by yellow circle on the statistical activation map. b - To examine whether these ROIs show differential neural response to information that is relevant versus irrelevant to later evaluations, we extracted the BOLD response from each of these regions and compared the mean percentage BOLD signal change during the presentation of evaluation-relevant versus evaluation-irrelevant person-descriptive sentences. The differential score was calculated by subtracting evaluation-irrelevant from evaluation-relevant responses, so positive scores correspond to stronger responses to the evaluation-relevant information. A significant differential responding was shown by the PCC and the amygdala, but not by the dmPFC.


Thinking like a trader reduces your loss aversion.

Sokol-Hessnera et al (open access). note that a cognitive regulation strategy can reduce loss aversion:
Research on emotion regulation has focused upon observers' ability to regulate their emotional reaction to stimuli such as affective pictures, but many other aspects of our affective experience are also potentially amenable to intentional cognitive regulation. In the domain of decision-making, recent work has demonstrated a role for emotions in choice, although such work has generally remained agnostic about the specific role of emotion. Combining psychologically-derived cognitive strategies, physiological measurements of arousal, and an economic model of behavior, this study examined changes in choices (specifically, loss aversion) and physiological correlates of behavior as the result of an intentional cognitive regulation strategy. Participants were on average more aroused per dollar to losses relative to gains, as measured with skin conductance response, and the difference in arousal to losses versus gains correlated with behavioral loss aversion across subjects. These results suggest a specific role for arousal responses in loss aversion. Most importantly, the intentional cognitive regulation strategy, which emphasized “perspective-taking,” uniquely reduced both behavioral loss aversion and arousal to losses relative to gains, largely by influencing arousal to losses. Our results confirm previous research demonstrating loss aversion while providing new evidence characterizing individual differences and arousal correlates and illustrating the effectiveness of intentional regulation strategies in reducing loss aversion both behaviorally and physiologically.

Wednesday, April 08, 2009

Fetal ethanol exposure increases ethanol intake of offspring

More sobering information on how maternal patterns of drug use, can be passed on to offspring, presumably by means of epigenetic chemosensory mechanisms.
Human epidemiologic studies reveal that fetal ethanol exposure is highly predictive of adolescent ethanol avidity and abuse. Little is known about how fetal exposure produces these effects. It is hypothesized that fetal ethanol exposure results in stimulus-induced chemosensory plasticity. Here, we asked whether gestational ethanol exposure increases postnatal ethanol avidity in rats by altering its taste and odor. Experimental rats were exposed to ethanol in utero via the dam's diet, whereas control rats were either pair-fed an iso-caloric diet or given food ad libitum. We found that fetal ethanol exposure increased the taste-mediated acceptability of both ethanol and quinine hydrochloride (bitter), but not sucrose (sweet). Importantly, a significant proportion of the increased ethanol acceptability could be attributed directly to the attenuated aversion to ethanol's quinine-like taste quality. Fetal ethanol exposure also enhanced ethanol intake and the behavioral response to ethanol odor. Notably, the elevated intake of ethanol was also causally linked to the enhanced odor response. Our results demonstrate that fetal exposure specifically increases ethanol avidity by, in part, making it taste and smell better. More generally, they establish an epigenetic chemosensory mechanism by which maternal patterns of drug use can be transferred to offspring. Given that many licit (e.g., tobacco products) and illicit (e.g., marijuana) drugs have noteworthy chemosensory components, our findings have broad implications for the relationship between maternal patterns of drug use, child development, and postnatal vulnerability.

Visual neglect overcome by pleasant music

Soto et al. make the fascinating observation that positive emotions can overcome the neglect of part of the visual field that can result from brain lesions:
During the past 20 years there has been much research into the factors that modulate awareness of contralesional information in neurological patients with visual neglect or extinction. However, the potential role of the individual's emotional state in modulating awareness has been largely overlooked. In the current study, we induced a pleasant and positive affective response in patients with chronic visual neglect by allowing them to listen to their pleasant preferred music. We report that the patients showed enhanced visual awareness when tasks were performed under preferred music conditions relative to when tasks were performed either with unpreferred music or in silence. These results were also replicated when positive affect was induced before neglect was tested. Functional MRI data showed enhanced activity in the orbitofrontal cortex and the cingulate gyrus associated with emotional responses when tasks were performed with preferred music relative to unpreferred music. Improved awareness of contralesional (left) targets with preferred music was also associated with a strong functional coupling between emotional areas and attentional brain regions in spared areas of the parietal cortex and early visual areas of the right hemisphere. These findings suggest that positive affect, generated by preferred music, can decrease visual neglect by increasing attentional resources. We discuss the possible roles of arousal and mood in generating these effects.

Tuesday, April 07, 2009

The end of moral philosophy

Again I am amazed at how well David Brooks keeps up with contemporary psychology and brain science, picking up on the recent upsurge in research on the good stuff in human nature like our evolved affiliative emotions. Check out this Op-Ed piece.

Another Twitter parody...

I couldn't resist passing this on:

Medial prefrontal cortex exhibits money illusion

My Feb. 23 post noted work showing, yet again, that we can be lured into making decisions by numbers that seem bigger than they really are. We apparently go with numerical values rather than real economic values. Weber et al. look at brain activity at accompanies the money illusion:
Behavioral economists have proposed that money illusion, which is a deviation from rationality in which individuals engage in nominal evaluation, can explain a wide range of important economic and social phenomena. This proposition stands in sharp contrast to the standard economic assumption of rationality that requires individuals to judge the value of money only on the basis of the bundle of goods that it can buy—its real value—and not on the basis of the actual amount of currency—its nominal value. We used fMRI to investigate whether the brain's reward circuitry exhibits money illusion. Subjects received prizes in 2 different experimental conditions that were identical in real economic terms, but differed in nominal terms. Thus, in the absence of money illusion there should be no differences in activation in reward-related brain areas. In contrast, we found that areas of the ventromedial prefrontal cortex (vmPFC), which have been previously associated with the processing of anticipatory and experienced rewards, and the valuation of goods, exhibited money illusion. We also found that the amount of money illusion exhibited by the vmPFC was correlated with the amount of money illusion exhibited in the evaluation of economic transactions.

Delayed brain development in humans compared with other primates

A prevailing view is that the appearance of many human-specific features during development has been made possible by a slowing down of the process, particularly in the brain (developmental retardation, or neoteny). Somel et al. prove the point by looking at gene expression in humans and other primates during development:
In development, timing is of the utmost importance, and the timing of developmental processes often changes as organisms evolve. In human evolution, developmental retardation, or neoteny, has been proposed as a possible mechanism that contributed to the rise of many human-specific features, including an increase in brain size and the emergence of human-specific cognitive traits. We analyzed mRNA expression in the prefrontal cortex of humans, chimpanzees, and rhesus macaques to determine whether human-specific neotenic changes are present at the gene expression level. We show that the brain transcriptome is dramatically remodeled during postnatal development and that developmental changes in the human brain are indeed delayed relative to other primates. This delay is not uniform across the human transcriptome but affects a specific subset of genes that play a potential role in neural development.

Monday, April 06, 2009

MindBlog is on the road again.

This is the time of year when I leave Fort Lauderdale with my new one year old children, shown in the photographs, to drive first to Austin Texas for a visit with my son and his wife, and then on to my home in Madison Wisconsin. (The photos show Marvin and Melvin checking out their carrier, then in the carrier on top of the car, but in fact they are given free range while in the car ). The posts in the queue this week for Tuesday through Friday are mainly passing on abstracts that I have found interesting, with an occasional figure.


The surprising power of neighborly advice.

I did a series of posts in June, 2006 abstracting Dan Gilberts book "Stumbling on Happiness." (You can use the blog search box to find them by entering the word "stumbling.") His main suggestion for knowing how you might actually feel emotionally about a desired future situation was simply to ask someone who has been there (become a successful doctor, actor, writer, etc.) Following in this vein, his group has recently obtained a very simple result concerning how people predict their future emotional reactions. Their abstract, following by some text:
Two experiments revealed that (i) people can more accurately predict their affective reactions to a future event when they know how a neighbor in their social network reacted to the event than when they know about the event itself and (ii) people do not believe this. Undergraduates made more accurate predictions about their affective reactions to a 5-minute speed date (n = 25) and to a peer evaluation (n = 88) when they knew only how another undergraduate had reacted to these events than when they had information about the events themselves. Both participants and independent judges mistakenly believed that predictions based on information about the event would be more accurate than predictions based on information about how another person had reacted to it.
Some context from the text of the article:
People make systematic errors when attempting to predict their affective reactions to future events...to overestimate how unhappy they will be after receiving bad test results, becoming disabled, or being denied a promotion, and to overestimate how happy they will be after winning a prize, initiating a romantic relationship, or taking revenge against those who have harmed them. Research suggests that the main reason people mispredict their affective reactions to future events is that they imagine those events inaccurately.

The 17th century writer François de La Rochefoucauld suggested that rather than mentally simulating a future event, people should consult those who have experienced it. "Before we set our hearts too much upon anything," he wrote, "let us first examine how happy those are who already possess it" . La Rochefoucauld was essentially suggesting that forecasters should use other people as surrogates for themselves, and the advantages of his "surrogation strategy" are clear: Because surrogation does not rely on mental simulation, it is immune to the many errors that inaccurate simulations produce.

The disadvantages of surrogation are also clear: Individuals differ, and thus, one person's affective reaction is almost certainly an imperfect predictor of another's. But there are at least two reasons to suspect that affective reactions are not as different as people may believe. First, affective reactions are produced in large part by physiological mechanisms that are evolutionarily ancient, which is why people the world over have very different beliefs and opinions but very similar affective reactions to a wide range of stimuli, preferring warm to cold, satiety to hunger, friends to enemies, winning to losing, and so on.
Their summary and conclusions:
In two experiments, participants more accurately predicted their affective reactions to a future event when they knew how a neighbor in their social network had reacted to it than when they knew about the event itself. Women made more accurate predictions about how much they would enjoy a date with a man when they knew how much another woman in their social network enjoyed dating the man than when they read the man's personal profile and saw his photograph. Men and women made more accurate predictions about how they would feel after being evaluated by a peer when they knew how another person in their social network had felt after being evaluated than when they previewed the evaluation itself. Although surrogation trumped simulation, both participants and independent judges had precisely the opposite intuition. By a wide margin, they believed that simulation was more likely than surrogation to produce accurate affective forecasts.

Two points are worthy of note. First, surrogation is by definition superior to simulation when individual differences are relatively small and simulations errors are relatively large, and it is inferior to simulation when the opposite is true. Although there is no way to know which of these is more typical in everyday life, the situations we studied—dating and peer-evaluation—are by no means exotic.

Second, although our experiments demonstrate the power of surrogation, they also suggest that people may not normally take advantage of this power. Our participants mistakenly believed that simulation was the superior strategy even after it had failed them, which suggests that people may be reluctant to engage in surrogation if they have the opportunity to do otherwise...it seems likely that in everyday life, La Rochefoucauld's advice—like the advice of good neighbors—is more often than not ignored. When we want to know our emotional futures, it is difficult to believe that a neighbor's experience can provide greater insight than our own best guess.

Language shapes fundamental unconscious visual perception.

From Thierry et al:
It is now established that native language affects one's perception of the world. However, it is unknown whether this effect is merely driven by conscious, language-based evaluation of the environment or whether it reflects fundamental differences in perceptual processing between individuals speaking different languages. Using brain potentials, we demonstrate that the existence in Greek of 2 color terms—ghalazio and ble—distinguishing light and dark blue leads to greater and faster perceptual discrimination of these colors in native speakers of Greek than in native speakers of English. The visual mismatch negativity, an index of automatic and preattentive change detection, was similar for blue and green deviant stimuli during a color oddball detection task in English participants, but it was significantly larger for blue than green deviant stimuli in native speakers of Greek. These findings establish an implicit effect of language-specific terminology on human color perception.

Friday, April 03, 2009

Previous choice shapes MRI signals reflecting future expectation and choice

An interesting piece from Dolan's group (open access) on correlates of future expected hedonic outcome:
Humans tend to modify their attitudes to align with past action. For example, after choosing between similarly valued alternatives, people rate the selected option as better than they originally did, and the rejected option as worse. However, it is unknown whether these modifications in evaluation reflect an underlying change in the physiological representation of a stimulus' expected hedonic value and our emotional response to it. Here, we addressed this question by combining participants' estimations of the pleasure they will derive from future events, with brain imaging data recorded while they imagined those events, both before, and after, choosing between them. Participants rated the selected alternatives as better after the decision stage relative to before, whereas discarded alternatives were valued less. Our functional magnetic resonance imaging findings reveal that postchoice changes in preference are tracked in caudate nucleus activity. Specifically, the difference in blood oxygenation level-dependent (BOLD) signal associated with the selected and rejected stimuli was enhanced after a decision was taken, reflecting the choice that had just been made. This finding suggests that the physiological representation of a stimulus' expected hedonic value is altered by a commitment to it. Furthermore, before any revaluation induced by the decision process, our data show that BOLD signal in this same region reflects the choices we are likely to make at a later time.

Brain activity related to estimated hedonic experience. Regions in which BOLD response was positively correlated with participants' ratings of estimated hedonic experience included the right and left caudate nucleus, previously associated with reward expectancy (a), as well as the left amygdala (b), and left pregenual anterior cingulate cortex (c), both previously shown to be engaged when imagining positive future autobiographical events.

The decline of science journalism.

Brumfield writes an essay on the rise of science blogging alongside the decay of science journalism:
because of a generalized downturn, especially in newspaper revenues, the traditional media are shedding full-time science journalists...At the same time, researcher-run blogs and websites are growing apace in both number and readership.

An online 'science of happiness' course.

Foundations of Positive Psychology, from the University of Pennsylvania College of Liberal and Professional Studies.

Thursday, April 02, 2009

Facebook, Twitter...can evolution keep up with us? A coming crash?

This post continues the thread started in last Monday's post on future shock and yesterday's iParticipate post. I try to stay informed about (and even join, to check out) the emerging connectivity contexts such as Facebook and Twitter (these links are to NY Times articles on these services, some graphics are shown below). All of these can bind us into increasingly complex and numerous interactions at an ever accelerating pace (see also Rapid Publishing). This may be congenial to the 18-30 demographic, but it leaves me with a sense of vertigo and overload. We know that human evolution occurs much more rapidly than previously thought, and that the plasticity of developing brains allows young people to acquire more complex mental abilities. But, how long will it be until our physiological and emotional repertoires, still largely those of our paleolithic ancestors, are sufficiently overwhelmed that the resulting stress and immune dysfunction increases from being a 'problem' to really shutting us down? I find myself wishing there was a STOP! function, with a RESET button, that could start us all over again with the rate knob dialed down ten-fold, in the spirit of slow food.

Facebook just passed the 200 million mark in membership. It started with 17-24 year olds, but the fastest growing member group of members is now over 35. What a 'friend' is on Facebook depends on how you define friend (click to enlarge):


Here is a small subset of the Twitter-verse, a subsection of a larger graphic that focuses on celebrities (click to enlarge):

MindBlog on Twitter

In spite of today's companion post on potential toxic effects of new social phenomena such as Twitter and Facebook, I can't give it a rest, and so have decided to jump in and see what happens. My twitter name is DericBownds. I've put a link to my "tweets" in the left column of the blog under the links to the podcasts. I'm thinking this might be useful not to tell you things like 'now I'm brushing my teeth', but rather to pass on ideas and URLs that I think are interesting, but that are unlikely to make it into a regular post. And to continue my (headache-inducing) entry into the Twitter/Facebook world I've linked the two. I hope I can back track and delete all this if I panic at some point.

Check out this humorous video on the follies:

Wednesday, April 01, 2009

Want some diet soda?

iParticipate - social participation networks

I guess I am a hard wired old curmudgeon. I wonder how many of you also get an overload headache when confronting this brave new social networking environment on the internet (Facebook, Twitter, etc)? I pass on a few points from an enthusiastic bubbly letter to Science Magazine titled "A National Initiative for Social Participation" which proposes an organized research program to study social action networks:
This program would systematically study the emerging phenomena, determine the sources of success or failure, and disseminate best practices. The payoffs are large enough to warrant an intense national effort akin to NASA's space program or the National Institutes of Health.
Some clips from the letter:
Health discussion groups have long been one of the Internet's success stories. Now, clever entrepreneurs are exploring new social participation ideas with projects such as the www.PatientsLikeMe.com Web site, where users offer their medical experiences in the hope of learning about treatment outcomes from one another. At the same time, these users are building a remarkable resource for medical research and discovery. Physicians have already discussed 30,000 cases at www.sermo.com, where they can offer insights about innovative treatments as well as detect unusual disease patterns. Large corporations also recognize the opportunities and are inviting users to store their medical histories in the Microsoft Health Vault or at Google Health.

Although social networking plays only a small role in national security, community safety could be enormously improved by expanding resident reporting systems, such as www.WatchJeffersonCounty.net, which collects reports of unusual behaviors. These reports provide important clues for civic officials to prevent crimes, control teenage gangs, or simply fix potholes.

The micro-blogging tool Twitter is now rapidly spreading, as users from Orange County fire-fighters to Mumbai police post their 140-character messages about where they are and what they are doing.

The benefits of social media participation are well understood by Obama's staff--during the campaign, they engaged 4 million donors and volunteers. To replicate their success, a National Initiative for Social Participation could stimulate effective collaborations in many professions, restore community social capital, and coordinate national service projects. The challenge is to understand what motivates participants, such as altruism, reputation, or community service. Researchers would have to develop fresh strategies that increased the conversion rates from readers to contributors from the currently typical 100 to 1 to much higher rates. Getting contributors to collaborate for ambitious efforts and to become leaders or mentors are further challenges. Coping with legitimate dangers such as privacy violations, misguided rumors, malicious vandalism, and infrastructure destruction or overload all demand careful planning and testing of potential solutions.

The huge research effort required for a National Initiative for Social Participation would tap the skills of computer scientists to build scalable and reliable systems, interface designers to accommodate diverse user needs, and social scientists to study successes and failures. The risks are substantial, but the payoffs could be enormous.

Markers of conscious access.

An interesting study from Gaillard et. al. :
What is the neural signature of the conscious perception of a visual stimulus? To address this question, we recorded neural activity directly from the brains of human subjects (who were undergoing neural surgery for medical reasons). This rare opportunity afforded greater spatial and temporal resolution than noninvasive methods used previously to probe the neural basis of consciousness. We compared neural activity concomitant with conscious and nonconscious processing of words by using a visual masking procedure that allowed us to manipulate the conscious visibility of briefly masked words. Nonconscious processing of words elicited short-lasting activity across multiple cortical areas, including parietal and visual areas. In sharp contrast, only consciously perceived words were accompanied by long-lasting effects (>200 ms) across a great variety of cortical sites, with a special involvement of the prefrontal lobes. This sustained pattern of neural activity was characterized by a specific increase of coherence between distant areas, suggesting conscious perception is broadcasted widely across the cortex.