Thursday, November 30, 2006

Predictive Codes for Forthcoming Perception in the Frontal Cortex

Incoming sensory information is often ambiguous, and the brain has to make decisions during perception. "Predictive coding" proposes that the brain resolves perceptual ambiguity by anticipating the forthcoming sensory environment, generating a template against which to match observed sensory evidence. Summerfield et al have observed a neural representation of predicted perception in the medial frontal cortex, while human subjects decided whether visual objects were faces or not. Perceptual decisions about faces were associated with an increase in top-down connectivity from the frontal cortex to face-sensitive visual areas, consistent with the matching of predicted and observed evidence for the presence of faces.

Figure: A simple dynamic causal model with hierarchically ordered bidirectional connections between vMFC (ventromedial frontal cortex), amygdala, FFA (fusiform face area), and IOG (inferior occipital gyrus). Face and nonface stimuli were modeled as inputs to IOG, and face sets as inputs to vMFC.

Wednesday, November 29, 2006

For Some People, Intimacy Is Toxic.... The Virtues of Solitude

I've been wanting to mention a brief essay in the Nov. 21 New York Times by psychotherapist Richard Friedman that describes a patient who defied the "article of faith among psychotherapists that an intimate human relationship is good for you." A software engineer pushed by family and constant therapy to be more social, he finally became engaged to a woman, and then came to Friedman after a suicide attempt, treatment for depression, and breaking from the engagement. Friedman found "He wasn't depressed or unhappy at all. He enjoyed his work as a software engineer immensely, and he was obviously successful at it. It was just that human relationships were not that important to him; in fact, he found them stressful...intimacy, it seems, is not for everyone."

It hardly seems surprising that genetic and developmental reasons lead some humans to be extremely affiliative, while others can be quite content in solitude. "Solitude: a return to the self" is in fact the title of an excellent and thoughtful book by Oxford University psychiatrist Anthony Storr. He notes: "The current emphasis upon intimate interpersonal relationships as the touchstone of health and happiness is a comparatively recent phenomenon. Earlier generations would not have rated human relationships so highly; believing, perhaps that the daily round, the common task, should furnish all we need to ask.." Storr provides an interesting history of how mental health came to be equated with the quality and quality of social relationships, and argues that a preference for solitude, self understanding, and a more muted social presence can be also be compatible with robust mental health.

Tuesday, November 28, 2006

The latest on Resveratrol enhancing health and longevity

Pretty soon we'll all be chowing down on grape skin extracts. I actually tried this stuff several years ago and thought it increased my joint I stopped. Many scientists recommed caution before plunging into yet another food supplement fad.

Anyway, here is the latest bit from a Nature article:

"Resveratrol (3,5,4'-trihydroxystilbene) extends the lifespan of diverse species including Saccharomyces cerevisiae, Caenorhabditis elegans and Drosophila melanogaster. In these organisms, lifespan extension is dependent on Sir2, a conserved deacetylase proposed to underlie the beneficial effects of caloric restriction. Here we show that resveratrol shifts the physiology of middle-aged mice on a high-calorie diet towards that of mice on a standard diet and significantly increases their survival. Resveratrol produces [biochemical] changes associated with longer lifespan......"

Monday, November 27, 2006

How we make our visual world appear to be constant.

At the same time that our brains command a body movement, they also generate an expection of the sensory outcome of that movement that is checked against the actual results. The nerve pathways underlying this elegant control system have not been well understood. Now comes a nice piece of work from Sommer and Wurtz. In their own words: "Each of our movements activates our own sensory receptors, and therefore keeping track of self-movement is a necessary part of analysing sensory input. One way in which the brain keeps track of self-movement is by monitoring an internal copy, or corollary discharge, of motor commands. This concept could explain why we perceive a stable visual world despite our frequent quick, or saccadic, eye movements: corollary discharge about each saccade would permit the visual system to ignore saccade-induced visual changes. The critical missing link has been the connection between corollary discharge and visual processing. Here we show that such a link is formed by a corollary discharge from the thalamus that targets the frontal cortex. In the thalamus, neurons in the mediodorsal nucleus relay a corollary discharge of saccades from the midbrain superior colliculus to the cortical frontal eye field. In the frontal eye field, neurons use corollary discharge to shift their visual receptive fields spatially before saccades...These experiments establish the first link between corollary discharge and visual processing, delineate a brain circuit that is well suited for mediating visual stability, and provide a framework for studying corollary discharge in other sensory systems."

Thursday, November 23, 2006

Making pain worse - basis of the Nocebo effect

In the nocebo effect - the opposite of the placebo effect - expectations of symptom worsening play a crucial role. Most of our knowledge about the analgesic placebo effect comes from the field of pain. It has been associated with decreased activity in the anterior cingulate and is diminished by antagonists of opiodergic peptide systems. The worsening of pain by exppectation has not been studied as thoroughly. Benedetti et al have now used a neuropharmacological approach to show that the hyperalgesic nocebo effect is associated with the activation of the CCKergic brain peptide system, as well as activation of the hypothalamic–pituitary–adrenal axis activated by stress. Thus the the analgesic placebo/hyperalgesic nocebo phenomenon may involve the opposite activation of endogenous opioidergic and CCKergic systems.

Wednesday, November 22, 2006

The Case Against Faith .. and what's the alternative

I've mentioned Sam Harris in previous posts. He is the author of two New York Times best sellers: "Letter to a Christian Nation" and "The End of Faith." Below I'm passing on a concise essay he recently wrote for Newsweek magazine.

What is absent from his critique of religion is a positive scientifically grounded alternative that meets the same human needs for solice and community that religion sometimes serves. Relevant to this is the recent NYTimes article "A Free-for-All on Science and Religion." which describes a meeting held at th Salk Institute in San Diego which "began to resemble the founding convention for a political party built on a single plank: in a world dangerously charged with ideology, science needs to take on an evangelical role, vying with religion as teller of the greatest story ever told."

The Harris essay:

"Despite a full century of scientific insights attesting to the antiquity of life and the greater antiquity of the Earth, more than half the American population believes that the entire cosmos was created 6,000 years ago. This is, incidentally, about a thousand years after the Sumerians invented glue. Those with the power to elect presidents and congressmen—and many who themselves get elected—believe that dinosaurs lived two by two upon Noah's Ark, that light from distant galaxies was created en route to the Earth and that the first members of our species were fashioned out of dirt and divine breath, in a garden with a talking snake, by the hand of an invisible God.

This is embarrassing. But add to this comedy of false certainties the fact that 44 percent of Americans are confident that Jesus will return to Earth sometime in the next 50 years, and you will glimpse the terrible liability of this sort of thinking. Given the most common interpretation of Biblical prophecy, it is not an exaggeration to say that nearly half the American population is eagerly anticipating the end of the world. It should be clear that this faith-based nihilism provides its adherents with absolutely no incentive to build a sustainable civilization—economically, environmentally or geopolitically. Some of these people are lunatics, of course, but they are not the lunatic fringe. We are talking about the explicit views of Christian ministers who have congregations numbering in the tens of thousands. These are some of the most influential, politically connected and well-funded people in our society.

It is, of course, taboo to criticize a person's religious beliefs. The problem, however, is that much of what people believe in the name of religion is intrinsically divisive, unreasonable and incompatible with genuine morality. One of the worst things about religion is that it tends to separate questions of right and wrong from the living reality of human and animal suffering. Consequently, religious people will devote immense energy to so-called moral problems—such as gay marriage—where no real suffering is at issue, and they will happily contribute to the surplus of human misery if it serves their religious beliefs.

A case in point: embryonic-stem-cell research is one of the most promising developments in the last century of medicine. It could offer therapeutic breakthroughs for every human ailment (for the simple reason that stem cells can become any tissue in the human body), including diabetes, Parkinson's disease, severe burns, etc. In July, President George W. Bush used his first veto to deny federal funding to this research. He did this on the basis of his religious faith. Like millions of other Americans, President Bush believes that "human life starts at the moment of conception." Specifically, he believes that there is a soul in every 3-day-old human embryo, and the interests of one soul—the soul of a little girl with burns over 75 percent of her body, for instance—cannot trump the interests of another soul, even if that soul happens to live inside a petri dish. Here, as ever, religious dogmatism impedes genuine wisdom and compassion.

A 3-day-old human embryo is a collection of 150 cells called a blastocyst. There are, for the sake of comparison, more than 100,000 cells in the brain of a fly. The embryos that are destroyed in stem-cell research do not have brains, or even neurons. Consequently, there is no reason to believe they can suffer their destruction in any way at all. The truth is that President Bush's unjustified religious beliefs about the human soul are, at this very moment, prolonging the scarcely endurable misery of tens of millions of human beings.

Given our status as a superpower, our material wealth and the continuous advancements in our technology, it seems safe to say that the president of the United States has more power and responsibility than any person in history. It is worth noting, therefore, that we have elected a president who seems to imagine that whenever he closes his eyes in the Oval Office—wondering whether to go to war or not to go to war, for instance—his intuitions have been vetted by the Creator of the universe. Speaking to a small group of supporters in 1999, Bush reportedly said, "I believe God wants me to be president." Believing that God has delivered you unto the presidency really seems to entail the belief that you cannot make any catastrophic mistakes while in office. One question we might want to collectively ponder in the future: do we really want to hand the tiller of civilization to a person who thinks this way?

Religion is the one area of our discourse in which people are systematically protected from the demand to give good evidence and valid arguments in defense of their strongly held beliefs. And yet these beliefs regularly determine what they live for, what they will die for and—all too often—what they will kill for. Consequently, we are living in a world in which millions of grown men and women can rationalize the violent sacrifice of their own children by recourse to fairy tales. We are living in a world in which millions of Muslims believe that there is nothing better than to be killed in defense of Islam. We are living in a world in which millions of Christians hope to soon be raptured into the stratosphere by Jesus so that they can safely enjoy a sacred genocide that will inaugurate the end of human history. In a world brimming with increasingly destructive technology, our infatuation with religious myths now poses a tremendous danger. And it is not a danger for which more religious faith is a remedy."

Tuesday, November 21, 2006

An inherited primate baseline for spatial cognition.

Haun et al report some interesting experiments that suggest that human infants inherit many of the same cognitive preferences and biases as our primate cousins but then go on to build cognitive structures that may diverge in various ways from this primate base under the influence of language and culture. Their experiments examine the spatial frames of reference (FoRs) used by children and adults in a Dutch village and a Khoisan hunter-gatherer community in Namibia, as well as by representative of the three major great ape genera (orangutans, gorillas, and chimpanzees; using animals in the Leipzig Zoo). Extensive field research in over 20 languages reveal that just three FoRs seem to be used. Some languages mainly use a relative EGOCENTRIC, viewpoint-dependent FoR with terms like front, back, left, and right: "The ball is to the left of the tree" (from my point of view). Some languages mainly use an intrinsic OBJECT CENTERED relational FoR, which makes reference to faceted objects, e.g., "The ball is at the front of the house." Some languages mainly use a third, so-called absolute GEOCENTRIC FoR in which linguistic descriptions use cardinal-direction type systems such as our North, South, East, and West: "The hot water is in the northern tap." Although most languages have several FoRs in their repertoire, egocentric relative constructions are predominant in European languages, whereas the geocentric absolute FoR is dominant, for example, in several indigenous languages of Australia, Papua New Guinea, Mexico, Nepal, and south West Africa.

Here is the experimental setup used for Dutch and Khosian children and adults:

Legend ((Click figure to enlarge)) Experimental setup in two consecutive example trials. Ten exactly identical cups were placed on two tables (five cups on each table). Participants were watching while a target was hidden under the cup depicted as white (HIDING). Then the participants moved to the other table and indicated where they thought a second target might be hidden (FINDING). The three differently striped cups show the different contingencies rewarded in the three consecutive blocks of trials.

Both children and adults were more accurate (made fewer errors) and were faster to learn the finding pattern that matched the FoR dominant in their language (egocentric for the Dutch, geocentric for the Khosian). This correlation is fully robust by age 8 and persists into adulthood.

Because of the shorter attention span of the ape participants, and because of their known limitations with respect to abstract reasoning, experimental conditions were simplified, so that three instead of five cups were on each table. As a result, the object-centered and geocentric conditions were collapsed. The three identical cups in a straight line offer only two alternative strategies: The egocentric one and an allocentric one, which could be based on either object-centered or geocentric cues. Experiments precisely analogous to the human experiment ware done, but more clear results were obtained in further experiments when rewards (food in one cup) were incorporated.

The bottom line, according to the authors: "All great ape genera prefer to process spatial relations based on environmental cues and not self. The standard methods of comparative cognition thus suggest a common phylogenetic inheritance of a preference for allocentric spatial strategies from the ancestor shared by all four existing genera of Hominidae (Pongo, Gorilla, Pan, and Homo). Based on this result, we argue that, at least for small-scale spatial relations, the inherited cognitive mode of operation is not, as argued by Kant and others, egocentric but preferably deploys environmental cues as common reference between objects."

Monday, November 20, 2006

Enhancing Cognition after Stress with Gene Therapy

This is the title of an article from Sapolsky's laboratory. Sapolsky is an amazing off the wall guy. His book "Why Zebras Don't Get Ulcers" is a classic on the biology of stress. He also has written fascinating stuff on aging. In this article he and his coworkers describe a clever trick for diminishing the impairment of memory acquisition and retrieval caused by the adrenal steroid hormones secreted during stress (glucocorticoids, or GCs). Estrogen, known to enhance spatial memory performance, can block the deleterious effects of GCs. The laboratory constructed a chimeric gene ("ER/GR") containing the hormone-binding domain of the GC receptor and the DNA binding domain of the estrogen receptor; as a result, ER/GR transduces deleterious GC signals into beneficial estrogenic ones. A deleterious effect of immobilization stress on spatial memory acquisition and retrieval in male rats was blocked by hippocampal expression of the ER/GR transgene. ER/GR also blocks the suppressive effects of GCs on expression of brain-derived neurotrophic factor (BDNF), a growth factor central to hippocampal-dependent cognition and plasticity, instead producing an estrogenic increase in BDNF expression. These experiments don't mean we are going to be able to use gene therapy to reverse the effects of stress on memory in humans any time soon. The clever tricks for getting transgenes into specific parts of rat brains don't yet exist for us humans.

Friday, November 17, 2006

Memory enhancement during your sleep...just wear an electric head strap?

I'm wondering how long it is going to be before we start seeings advertisements for "effortless memory enhancement" devices inspired by the work of Marshall et al reported in Nature. (For example, a tiara that places button electrodes bilaterally over the mastoids and frontolateral cortex and generates a low oscillating current around 0.75 cycles per second during non-REM sleep). Although I'm tempted to cook down their description to make it a bit more palatable, their abstract does do the job:

"There is compelling evidence that sleep contributes to the long-term consolidation of new memories. This function of sleep has been linked to slow per se is unclear, but can easily be investigated by inducing the extracellular oscillating potential fields of interest. Here we show that inducing slow oscillation-like potential fields by transcranial application of oscillating potentials (0.75 Hz) during early nocturnal non-rapid-eye-movement sleep, that is, a period of emerging slow wave sleep, enhances the retention of hippocampus-dependent declarative memories in healthy humans. The slowly oscillating potential stimulation induced an immediate increase in slow wave sleep, endogenous cortical slow oscillations and slow spindle activity in the frontal cortex. Brain stimulation with oscillations at 5 Hz—another frequency band that normally predominates during rapid-eye-movement sleep—decreased slow oscillations and left declarative memory unchanged. Our findings indicate that endogenous slow potential oscillations have a causal role in the sleep-associated consolidation of memory, and that this role is enhanced by field effects in cortical extracellular space."

Thursday, November 16, 2006

Is there a biology of intelligence?

Because I once had an article in Behavioral and Brain Science, I receive email on final drafts of forthcoming articles for review. The purpose of this post is to point you to an interesting review and synthesis by R.E. Jung and R.J. Haier that will appear in a future issue. Its title is "The Parieto-Frontal Integration Theory (P-FIT) of Intelligence: Converging Neuroimaging Evidence." (Note added in Sept, 2007: the reference is Behavioral and Brain Sciences (2007) 30, 135-187)

The article reviews 37 modern neuroimaging studies, including functional (i.e. functional Magnetic Resonance Imaging, Positron Emission Tomography) and structural (i.e. Magnetic Resonance Spectroscopy, Diffusion Tensor Imaging,Voxel Based Morphometry)paradigms. They converge on a striking consensus suggesting that variations in a distributed network predict individual differences found on intelligence and reasoning tasks. They describe this network as the Parieto-Frontal Integration Theory: P-FIT. (How is a network a theory? Oh well, not to worry).

The P-FIT includes, by Brodmann Areas (BAs): dorsolateral prefrontal cortex (BAs 6, 9, 10, 45, 46, 47), the inferior (BAs 39/40) and superior parietal (BA 7) lobe, the anterior cingulate (BA 32), and regions within the temporal (BAs 21, 37) and occipital lobes (BAs 18 & 19). White matter regions (i.e., arcuate fasciculus) are also implicated.

The P-FIT is examined in light of findings from both human lesion studies, including missile wounds, frontal lobotomy/leukotomy, temporal lobectomy, and lesions resulting in damage to the language network (e.g., aphasia), as well as from imaging research identifying brain regions under significant genetic control. Overall, they conclude that modern neuroimaging techniques are beginning to articulate a biology of intelligence. They propose that the P-FIT provides a parsimonious account for many of the empirical observations to-date relating individual differences in intelligence test scores to variations in brain structure and function. They hope the model provides a framework for testing new hypotheses in future experimental designs.

Here is a graphic of the brain areas (copyright Cambridge University Press).

Legend: Brain regions by Brodmann Area (BA) associated with better performance on measures of intelligence and reasoning. Numbers represent BAs; solid blue circles = predominant left hemisphere associations; shadow blue circle = predominant left medial associations; shadow red circles = predominant bilateral associations; yellow arrow = arcuate fasciculus.

Wednesday, November 15, 2006

Gender and sexual orientation regulate the effect of invisible images.

As we are contantly bombarded with vast amounts of information, selective attention mechanisms help us quickly attend to what is important while ignoring what is irrelevant. It makes ecological and evolutionary sense if important events can influence our spatial attention even before we become aware of the event. Recent studies have shown that subliminal presentation of emotional stimuli can modulate activity of the amygdala. Jiang et al ask whether activation of the emotional system directs observers' attention to the stimulus in the absence of awareness.

They show that information that has not entered our consciousness, such as interocularly suppressed (invisible) erotic pictures, can direct the distribution of spatial attention. They further show that invisible erotic information can either attract or repel observers' spatial attention depending on their gender and sexual orientation. While unaware of the suppressed pictures, heterosexual males' attention was attracted to invisible female nudes, heterosexual females' attention was attracted to invisible male nudes, gay males behaved similarly to heterosexual females, and gay/bisexual females performed in-between heterosexual males and females.

Here is their description of how information is presented so that it does not enter consciousness. "In the interocular suppression paradigm, a pair of high-contrast dynamic noise patches are presented to both sides of a fixation point in one eye, and a test picture and its scrambled control are presented to the fellow eye in spatial locations corresponding to the noise patches. Because of strong interocular suppression, the intact meaningful image and its scrambled control remain invisible for the period they are presented. If the suppressed images exert a location-specific effect on the attentional system, these images could potentially act as attentional cues that would influence the distribution of spatial attention and thus performance on a subsequent detection task."

(click on image to enlarge it)
Figure: Schematic representation of the experimental paradigm for the invisible condition. For the visible condition, the noise patches were replaced with the same pair of intact and scrambled pictures presented to the other eye. In each trial, observers pressed one of two buttons to indicate the perceived orientation (CW or CCW) of a Gabor patch (the circle with lines in the right frame) briefly presented on either side of fixation. In the invisible condition, as shown, if observers detected any difference between the two sides of the fixation, they pressed another button to abort that trial.

Heterosexual male observers were more accurate at the orientation discrimination task when the Gabor targets followed the site of the invisible nude female pictures (attentional benefit) and were less accurate when the Gabor patches were at the site of invisible nude male pictures (attentional cost). Thus, heterosexual male observers' attention was attracted to nude female images and was repelled from nude male images, even though the images were not consciously perceived by the observers. Similarly, heterosexual female participants showed an attentional benefit (attraction) to invisible nude male pictures (positive attentional effect, although they did not show a significant attentional effect to invisible nude female pictures. Gay males had a similar pattern to female participants in that invisible female nude pictures did not attract their attention while male erotic images enhanced performance. Gay/bisexual females fell in-between the heterosexual male group and the heterosexual female group.

Tuesday, November 14, 2006

Mind over Matter: how depression causes bone loss through nerve activation.

The chronic activation of the arousal part of our autonomic nervous system (the sympathetic nervous system) that can occur during stress has been shown to cause an array of degenerative effects. Yirmiya et al, using a mouse model system, now link this system to the low bone mass and increased incidence of osteoporotic fractures associated with major depression. They show that mice subjected to chronic mild stress (CMS) show behavioral depression and impaired bone mass and structure. Antidepressant therapy, which prevents the behavioral responses to CMS, completely inhibits the decrease in bone formation and markedly attenuates the CMS-induced bone loss. The depression-triggered bone loss is associated with a substantial increase in bone norepinephrine levels and can be blocked by the beta-adrenergic antagonist propranolol, suggesting that the sympathetic nervous system mediates the skeletal effects of stress-induced depression. These results demonstrate an interaction among behavioral responses, the brain, and the skeleton, which leads to impaired bone structure. This suggests that depression is a potential major risk factor for osteoporosis in the aging population.

Monday, November 13, 2006

Imaging the brain during "speaking in tongues"

The charismatic practice of speaking with the full conviction that God is talking through you has ancient roots in many religious traditions, notably the Old and New Testaments. Its technical term is glossolalia. It is experienced as a normal and expected behavior in religious prayer groups in which the individual appears to be speaking in an incomprehensible language.

Newberg et al. at the University of Pennsylvania have now performed brain imaging on five women while they spoke in tongues (Psychiatry Research: Neuroimaging, Volume 148, Issue 1 , 22 November 2006, Pages 67-71) They tracked changes in blood flow in each woman’s brain as she sang a gospel song and again while speaking in tongues.

An interesting difference was observed between these two emotional, devotional activities , described in a review by Carey, was that the "frontal lobes — the thinking, willful part of the brain through which people control what they do — were relatively quiet, as were the language centers. The regions involved in maintaining self-consciousness were active. The women were not in blind trances, and it was unclear which region was driving the behavior."... "a co-author of the study, was also a research subject. She is a born-again Christian who says she considers the ability to speak in tongues a gift. “You’re aware of your surroundings,” she said. “You’re not really out of control. But you have no control over what’s happening. You’re just flowing. You’re in a realm of peace and comfort, and it’s a fantastic feeling.”

"The scans also showed a dip in the activity of the left caudate. .. the caudate is usually active when you have positive affect, pleasure, positive emotions, and is also involved in motor and emotional may be that practitioners, while mindful of their circumstances, nonetheless cede some control over their bodies and emotions."

Friday, November 10, 2006

Putting humans and their climate in perspective

I always find it theraputic to renew my awareness of the fact that humans as we know them occupy only an eyeblink in the timeline of complex life on this planet. If just the period in which complex organisms arose is thought of in terms of a single year, fish would have appeared in January, land animals in March, dinosaurs in June, monkeys in December and humans late on New Year’s Eve.

This graphic from the Nov. 7 Science section of the NYTimes, prepared by Robert Rohde at Berkeley, is so striking that I wanted to pass it on. Carbon dioxide levels have been much higher at various times in the past than they are now. The accompanying article helps frame the debate over carbon dioxide in the atmosphere.

Thursday, November 09, 2006

Deric and MindBlog are moving south for the winter...

From Madison, WI to Fort Lauderdale, FL. The pictures below show why… Five years after retiring as a department chair at the Univ. of Wisconsin I still am grateful and a bit incredulous that I can actually do what I want to do when I feel like doing it. I'm not sure how quickly I'll get my broadband connection running again, so apologies ahead of time for any lapse in posting.

From my office in Bock Labs and the Wisconsin summer, to what it looks like now (It was 16 degress Farenheit last week), to the new alternative:

Wednesday, November 08, 2006

The Brain Making Choices: The Lesser of Two Evils or the Better of Two Goods....

The relevance of this topic to yesterday's election was mentioned in the post just below. Blair et al. have now used functional magnetic resonance imaging to delineate the functional roles of the ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortices (ACd), which are considered important for reward-based decision making. Response choice often occurs in situations where both options are desirable (e.g., choosing between mousse au chocolat or crème caramel cheesecake from a menu) or, alternatively, in situations where both options are undesirable. Moreover, response choice is easier when the reinforcements associated with the objects are far apart, rather than close together, in value. The authors used functional magnetic resonance imaging to delineate the functional roles of the vmPFC and ACd by investigating these two aspects of decision making: (1) decision form (i.e., choosing between two objects to gain the greater reward or the lesser punishment), and (2) between-object reinforcement distance (i.e., the difference in reinforcements associated with the two objects). Responses within the ACd and vmPFC were both related to decision form but differentially. ACd showed greater responses when deciding between objects to gain the lesser punishment, while vmPFC showed greater responses when deciding between objects to gain the greater reward. Moreover, vmPFC was sensitive to reinforcement expectations associated with both the chosen and the forgone choice. In contrast, responses within ACd, but not vmPFC, related to between-object reinforcement distance, increasing as the distance between the reinforcements of the two objects decreased.

Figure: anterior cingulate and ventromedial prefrontal areas examined in study.

Tuesday, November 07, 2006

The psychology of framing in this election - are we deciding whom to accept or whom to reject?

Barry Schartz (a psychology professor at Swarthmore, and author of “The Paradox of Choice: Why More Is Less.”) has a nice OpEd piece in today's NYTimes which I want to pass on because it is relevant to today's election...

ANOTHER national election season has come to an end — the sorriest, sleaziest, most disheartening and embarrassing in memory. The best one can hope for is a candidate who is a complete cipher. How has American electoral politics come to this?

I think we can gain insight from a study published by the psychologist Eldar Shafir 13 years ago. Suppose you are confronted with the following problem:

You’re serving as a juror in a custody case in which each parent is demanding sole custody of an only child. The facts of the case are complicated by ambiguous economic, social and emotional considerations, and you decide to base your decision entirely on the following few observations:

Parent A
• average income
• reasonable rapport with child
• relatively stable social life
• average working hours
• average health

Parent B
• above-average income
• close relationship with child
• extremely active social life
• lots of work-related travel
• minor health problems

To which parent would you award sole custody of the child?

Parent A is average in every way, without compelling positive or negative features. Parent B has a mix of strong positive (very close to the child) and strong negative (lots of travel) features. Asked to make this choice, the majority of respondents — 64 percent — choose Parent B.

What makes this study really interesting is what happens when another group of respondents is given the same character sketches, but asked a slightly different question: “To which parent would you deny custody of the child?” Here again, a majority, 55 percent, choose Parent B.

How can it be that a majority both accept and reject the same parent?

Professor Shafir’s explanation is that when people are asked whom to accept, they look for positive features in the parents — reasons to accept one over the other — and Parent B has them. In contrast, when people are asked whom to reject, they look for negative features — and again, Parent B has them. No matter which question you ask, Parent B stands out.

What does this tell us about modern electoral politics? When you go into the voting booth, you’re trying to decide whom to accept or whom to reject. Are you judging who the good candidate is or who the less bad candidate is?

The effort by each side to coat the opposition in slime has made many of us cynical, giving us the sense that our task is to reject the worst, not select the best. Nobody’s any good, we think, but some are worse than others. Let’s keep those candidates out of office. Our job becomes one of denying, not awarding, office.

What that means is that if you want to win an election, you need to find candidates like Parent A, who give us no reason to say no, rather than Parent B, who present a complex set of features, some attractive and some problematic.

If somehow the cynicism lifted, and we saw ourselves charged with the task of deciding who to say yes to, we’d have more candidates like Parent B. Just one negative feature would not be enough to disqualify someone, in our minds. There would be little to gain by capturing and broadcasting “macaca moments,” or subtly invoking old Southern fears of black men cavorting with white women. Candidates would be able to take positions and speak their minds. This might lead to the arrival of candidates who actually have positions and minds. We might even be willing to risk generating a little enthusiasm at the prospect of being led by them.

But unless something is done to quell “gotcha” journalism and relentlessly negative campaigning — and as long as we continue to enter the voting booth looking for reasons to say no — the ciphers will be the winners.

The evolution of morals - a nudge of clarity

Relevant to my recent post, This letter to the editor in the science section of the NYTimes from my Univ. of Wisconsin colleague Larry Shapiro, in the Philosophy Department:

To the Editor:

As a professional philosopher, I found myself with no worries about whether Marc Hauser’s theory would put my colleagues in ethics out of business. There’s a tremendous difference between the two questions: 1) Why do human beings make the judgments of right and wrong that they do?; and 2) Are these judgments correct?

Perhaps an evolutionary story can suffice to answer the first question, but I can’t imagine how it might answer the second.

Larry Shapiro
Madison, Wis.

Where your brain sizes up your competition...

Goodman reports on a study led by Caroline Zink, a postdoctoral fellow at the National Institute of Mental Health, that found that several brain regions showed increased activity when people were evaluating their standings in a social hierarchy. Zink recruited 24 healthy volunteers — 12 men and 12 women — and had them play a game of skill while their brain activity was imaged using fMRI. Participants were told they would simultaneously be playing two other people: an inferior “one star” player and a superior “three star” player. These other players were invented, however, and their actions carried out by a computer. To convince the participants that the other players where real, the research team constructed elaborate ruses — postponing the start of the game for 15 minutes because another player was running late, for example, or leaving the room under the pretense of helping a player get set up. The volunteers were asked to press a button as soon as they were given a signal. If they responded quickly enough, they won a dollar. Though the researchers emphasized that the participants were not competing against the other players, they also made sure that the volunteers saw the scores of the one-star players and three-star players.

The results were clear and strong...When the volunteers won more money than the three-star players, raising their status in the game, the brain scanner showed increased activity in three brain regions: the anterior cingulate, an area that has been shown to monitor conflict and resolve discrepancies; the medial prefrontal cortex, which processes thoughts about other people; and the precuneus, a region that some speculate is involved in the brain’s ability to think about itself.

In contrast, when the one-star players won more money during the game than the volunteers, lowering their status, activity increased in the ventral striatum and the insular cortex, or insula. This area appears to be responsible for the somatic representation of emotional states, such as disgust. The ventral striatum is a deep brain structure linked in primates to motivation and reward, and may be part of the neural circuitry that keeps track of progress through learning.

Monday, November 06, 2006

No effect of DHEA or Testosterone in Elderly

Nicholas Bakalar reviews a study reported in the New England Journal of Medicine involving 87 men, average age 79, and 57 women, average age 68. The men were divided into three groups who received daily doses of 5 milligrams of testosterone, 75 milligrams of DHEA or a placebo. The women were divided into two groups that received either DHEA or a placebo.

Friday, November 03, 2006

Are we born with a moral grammar?

By now I've probably read at least 5 mixed (mainly positive) reviews of Mark Hauser's new book "Moral Minds," and the commentary on the book by Nicholas Wade in the 10/31/06 New York Times stirs me to mention it in a post.

Hauser suggests that we have a universal and innate capacity for developing moral rules analogous to our capacity to develop language in the presence of other humans. A more reserved review in an earlier New York Times Book Review Magazine by Richard Rorty raises some concerns: "The exuberant triumphalism of the prologue to “Moral Minds” leads the reader to expect that Hauser will lay out criteria for distinguishing parochial moral codes from universal principles, and will offer at least a tentative list of those principles. These expectations are not fulfilled......the reader is left guessing about how he proposes to distinguish morality not just from etiquette, but also from prudential calculation, mindless conformity to peer pressure and various other things. This makes it hard to figure out what exactly his moral module is supposed to do. It also makes it difficult to envisage experiments that would help us decide between his hypothesis and the view that all we need to internalize a moral code is general-purpose learning-from-experience circuitry — the same circuitry that lets us internalize, say, the rules of baseball."

A review by Bloom and Jarudi in Nature makes some further points: "Certain deep parallels between language and morality make Hauser's proposal worth taking seriously. ....In other regards, however, language seems very different from morality. For one thing, linguistic knowledge is distinct from emotion. You might be disgusted or outraged by what somebody says, but the principles that make sense of sentences are themselves entirely cold-blooded. Your eyes do not well with tears as you unconsciously determine the structural geometry of a verb phrase. By contrast — and Hauser wrestles with this throughout Moral Minds — even those who accept that some moral capacity is innate often see it as inextricably linked to emotion. Perhaps the universal core of morality is a set of emotional responses — disgust, shame, sympathy, guilt and so on — that are triggered by certain situations. This hypothesis is supported by clear demonstrations that, at least in some circumstances, emotion precedes intuition. ...A different concern is that languages are combinatorial symbolic systems. An English speaker, for example, knows perhaps hundreds of thousands of words, and also knows principles of syntax that dictate how these words combine with one another to form sentences. There are other combinatorial systems in human cognition, such as number and music, but it's not clear that morality is one of them. Even if it is distinct from emotion, moral knowledge might be better characterized as a small list of evolved rules, perhaps simple (such as a default prohibition against intentional harm), perhaps complex (such as some version of the doctrine of double effect), but still very different in character from linguistic knowledge."

Countering these reservations, from Wade's article: "Much of the present evidence for the moral grammar is indirect. Some of it comes from psychological tests of children, showing that they have an innate sense of fairness that starts to unfold at age 4. Some comes from ingenious dilemmas devised to show a subconscious moral judgment generator at work. These are known by the moral philosophers who developed them as “trolley problems." ...Suppose you are standing by a railroad track. Ahead, in a deep cutting from which no escape is possible, five people are walking on the track. You hear a train approaching. Beside you is a lever with which you can switch the train to a sidetrack. One person is walking on the sidetrack. Is it O.K. to pull the lever and save the five people, though one will die?...Most people say it is....Assume now you are on a bridge overlooking the track. Ahead, five people on the track are at risk. You can save them by throwing down a heavy object into the path of the approaching train. One is available beside you, in the form of a fat man. Is it O.K. to push him to save the five? Most people say no, although lives saved and lost are the same as in the first problem." (Note: Brain imagining experiments show the second scenario activates emotional areas of the brain that counter the more frontal rational areas engaged by the first scenario.).. "Why does the moral grammar generate such different judgments in apparently similar situations? It makes a distinction, Dr. Hauser writes, between a foreseen harm (the train killing the person on the track) and an intended harm (throwing the person in front of the train), despite the fact that the consequences are the same in either case. It also rates killing an animal as more acceptable than killing a person... Many people cannot articulate the foreseen/intended distinction, Dr. Hauser says, a sign that it is being made at inaccessible levels of the mind. This inability challenges the general belief that moral behavior is learned. For if people cannot articulate the foreseen/intended distinction, how can they teach it?"

This last point seems weak, all kinds of teaching occurs without articulation. Even given that some moral judgements can be more rapid than conscious thought, or are carried out by unconscious background processes, how do we design experiments to distinguish whether they are innate or learned? We need a paradigm as powerful that provided by the Nicaraguan school for deaf children, where the children invented among themselves a unique sign language following Chomsky's rules for a universal grammar. Would a group of children isolated from outside moral influence develop universal moral codes (an experiement that can't be done) or would we have the scenario of Golding's "The Lord of the Flies?"

Tony Auth and Tom Tooles on the resveratrol story

Thursday, November 02, 2006

Self recognition - humans, apes, dolphins...and now elephants

Plotnik, de Waal, and Reiss report in PNAS that mirror self recognition (MSR), considered an indicator of self awareness, can be observed in Asian elephants. Slightly edited from their abstract: "MSR is thought to correlate with higher forms of empathy and altruistic behavior. Apart from humans and apes, dolphins and elephants are also known for such capacities. After the recent discovery of MSR in dolphins (Tursiops truncatus), elephants thus were the next logical candidate species. The authors exposed three Asian elephants (Elephas maximus) to a large mirror to investigate their responses. Animals that possess MSR typically progress through four stages of behavior when facing a mirror: (i) social responses, (ii) physical inspection (e.g., looking behind the mirror), (iii) repetitive mirror-testing behavior, and (iv) realization of seeing themselves. Visible marks and invisible sham-marks were applied to the elephants' heads to test whether they would pass the litmus "mark test" for MSR in which an individual spontaneously uses a mirror to touch an otherwise imperceptible mark on its own body. Here, we report a successful MSR elephant study and report striking parallels in the progression of responses to mirrors among apes, dolphins, and elephants. These parallels suggest convergent cognitive evolution most likely related to complex sociality and cooperation.

Above video (click the rectangle to play) was taken from the Elmo lipstick camera embedded in the mirror on Happy's first day of marking. Happy repetitively touches the mark or the area immediately around the mark with her trunk while in full view of the mirror. She never touches the sham-mark during this session.

Followup: take resveratrol and continue to pig out...

In my 10/31/06 post on caloric restriction I elected not to get into the resveratrol story, but followup articles in the NY Times and Nature now force me to do that (....added note: after writing this post I see the resveratrol story on the NBC Evening News with Brian Williams!) Experiments showing that resveratrol extends lifespan in lower animals have been extended now to mice. Several Biotec companies are testing improved versions of the compound.

Here's the abstract from the Nature article:

Resveratrol (3,5,4'-trihydroxystilbene) extends the lifespan of diverse species including Saccharomyces cerevisiae, Caenorhabditis elegans and Drosophila melanogaster. In these organisms, lifespan extension is dependent on Sir2, a conserved deacetylase proposed to underlie the beneficial effects of caloric restriction. Here we show that resveratrol shifts the physiology of middle-aged mice on a high-calorie diet towards that of mice on a standard diet and significantly increases their survival. Resveratrol produces changes associated with longer lifespan, including increased insulin sensitivity, reduced insulin-like growth factor-1 (IGF-I) levels, increased AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC-1alpha) activity, increased mitochondrial number, and improved motor function. Parametric analysis of gene set enrichment revealed that resveratrol opposed the effects of the high-calorie diet in 144 out of 153 significantly altered pathways. These data show that improving general health in mammals using small molecules is an attainable goal, and point to new approaches for treating obesity-related disorders and diseases of ageing.

Wednesday, November 01, 2006

How emotions modulate memory through the amygdala

Transmission of sensory information through the rhinal cortices is essential for hippocampus-dependent learning. In Nature Neuroscience Quirk & Vidal-Gonzalez provide a nice summary of work by Paz. et. al. showing that amygdala activity elicited by an unexpected reward facilitates communication from perirhinal to entorhinal cortex, providing a physiological mechanism for emotional modulation of memory.

Figure: The amygdala enhances transfer of sensory information.
Sensory input flows from the neocortex to the hippocampus via the rhinal cortices (descending arrows). The hippocampus in turn assists in consolidating and storing this information through projections back to neocortex (ascending arrows). (a) During spontaneous activity, with low amygdala firing rates (blue traces on left), transfer of information from perirhinal cortex (Prh) to entorhinal cortex (Ent) is minimal (thin red arrows). (b) Following reward, the amygdala increases its firing rate and synchrony. This enables the transfer of sensory information through the rhinal cortices into the hippocampus (large red arrow).