Thursday, August 31, 2006
After interviewing candidates who ranged from genuine to humorous to bizarre, Joshua Boden (35) was chosen to attempt to establish his "Church of Now", a God-optional religion that lists 14 precepts, including, “The only ‘sin’ is not living fully,” and, “This life is the one that counts; this IS your eternal reward.” The religion has elements of Buddhism, Taoism and New Age thinking. Although some of the beliefs might sound unorthodox and nonreligious (“Laughter is a must!”), Mr. Boden is earnest in his beliefs and his desire to establish a spiritual community. The going as been rocky so far. Potential followers indicated the presentation was not persuasive and authoritative ("Believe this!") enough.
Wednesday, August 30, 2006
An NIMH research team, led by Jay Giedd, has made a movie of normal brain changes from ages 5 to 20. It reveals that the grey matter thickens in childhood but then thins in a wave that begins at the back of the brain and reaches the front by early adulthood (see movie, below). The process completes itself sooner in girls than in boys. This corresponds to a long-held assumption that adolescence sees the prefrontal cortex regions that handle executive functions 'waking up' and to the conventional wisdom that girls mature faster in this respect.
(Click on the thin rectangular box below this line if you want to start the movie)
A reward centre on overdrive coupled with planning regions not yet fully functional could make an adolescent an entirely different creature to an adult when it comes to seeking pleasure. In adolescents given a medium or large reward, the nucleus accumbens (part of the reward center of the brain) reacts more strongly than in children or adults
A speculation is that the lag between the frontal regions and the reward centre is an evolutionary feature, not a bug. "You need to engage in high-risk behaviour to leave your village and find a mate," and risk-taking soars at just the same time as hormones drive adolescents to seek out sexual partners.... in rodents, primates and even some birds, adolescence is a time of risky business, seeking out same-age peers and fighting with parents, which "all help get the adolescent away from the home territory".
"I don't think we can fight the biology of wanting to take risks and try on different identities. ...As a society, we can give kids creative, positive outlets that do not lead to irreversible mistakes...Attempts to push kids towards safe sex or pharmaceutical temperance shouldn't be expected to succeed if they simply explain consequences....Adolescents have some fundamental qualities to them that are not voluntary and not easily modified by rational, information-based interventions."
Tuesday, August 29, 2006
Monday, August 28, 2006
Here are the composite prototypes they offer:
Characteristics of the male "Sexy face" in the comparison to the "unsexy face":
* Browner skin
* Narrower facial shape
* Less fat
* Fuller and more symmetrical lips
* Darker eye brows
* More and darker lashes
* Upper half of the face broader in relation to the lower
* Higher cheek bones
* Prominent lower jaw
* More prominent chin
* No receding brows
* Thinner lids
* No wrinkles between nose and corner of the mouth
Characteristic features of the female "sexy face" in comparison to the "unsexy face":
* Suntanned skin
* Narrower facial shape
* Less fat
* Fuller lips
* Slightly bigger distance of eyes
* Darker, narrower eye brows
* More, longer and darker lashes
* Higher cheek bones
* Narrower nose
* No eye rings
* Thinner lids
Friday, August 25, 2006
"Different forms of learning and memory depend on functionally and anatomically separable neural circuits [Squire, L. R. (1992) Psychol. Rev. 99, 195–231]. Declarative memory relies on a medial temporal lobe system, whereas habit learning relies on the striatum [Cohen, N. J. & Eichenbaum, H. (1993) Memory, Amnesia, and the Hippocampal System (MIT Press, Cambridge, MA)]. How these systems are engaged to optimize learning and behavior is not clear. Here, we present results from functional neuroimaging showing that the presence of a demanding secondary task during learning modulates the degree to which subjects solve a problem using either declarative memory or habit learning. Dual-task conditions did not reduce accuracy but reduced the amount of declarative learning about the task. Medial temporal lobe activity was correlated with task performance and declarative knowledge after learning under single-task conditions, whereas performance was correlated with striatal activity after dual-task learning conditions. These results demonstrate a fundamental difference in these memory systems in their sensitivity to concurrent distraction. The results are consistent with the notion that declarative and habit learning compete to mediate task performance, and they suggest that the presence of distraction can bias this competition. These results have implications for learning in multitask situations, suggesting that, even if distraction does not decrease the overall level of learning, it can result in the acquisition of knowledge that can be applied less flexibly in new situations."
Thursday, August 24, 2006
Sensing or exploring the nature of our elemental physical existence, our body breathing and homeostasis, is a focus of the Buddha's First Foundation of Mindfulness. This first foundation corresponds to physical elements of the body and homeostasis (regulation of blood flow, body temperature, etc.) These functions center in primitive brain stem structures we share with reptiles and other vertebrates. This core regulates interactions with the physical world elemental to having a self that we seldom think about - like breathing, supporting ourselves against gravity, seeing, tasting, smelling, touching, hearing.
These core structures also regulate our urge to remedy hunger, to have sex, to approach or avoid, to flee or fight when suddenly presented with very threatening situations. Our experience of these primary and instinctual basic drives, in its urgency and automaticity, has a very different quality than our experience of thoughts or more complicated emotions. The Buddha's Second Foundation of Mindfulness rests on the sentience of the nervous system which can note these elemental feelings, impressions of pleasant/unpleasant/neutral/painful, etc. We can, in more quiet moments of reflection or meditation note the more muted `flickers' of these primal forces, appearing and disappearing almost as transient quantal energies.
Our human introspective access to, observation of, emotional feelings more nuanced than the basic drives mentioned above is the focus of the Buddha's third foundation of mindfulness (affection, fear, anger, sadness, playfulness, etc.). These are regulated by a new kind of cortex that appears in mammals between the brain stem and the outer layer of the cortex, usually referred to as the limbic system.
Finally, our higher level cognitive abilities associated with the newer cortex (neocortex) that forms the top layers or our brain - our ability to note how thoughts and feelings are produced, as natural occurrences like breathing or the heartbeat - are a focus of the Buddha's fourth foundation of mindfulness.
Nisker's book has several sections of exercises or meditations useful in sensing layers of the self, its evolutionary nature, and its symbiosis with the external social and physical world.
Wednesday, August 23, 2006
"The developmental and evolutionary mechanisms behind the emergence of human-specific brain features remain largely unknown. However, the recent ability to compare our genome to that of our closest relative, the chimpanzee, provides new avenues to link genetic and phenotypic changes in the evolution of the human brain. We devised a ranking of regions in the human genome that show significant evolutionary acceleration. Here we report that the most dramatic of these 'human accelerated regions', HAR1, is part of a novel RNA gene (HAR1F) that is expressed specifically in Cajal–Retzius neurons in the developing human neocortex from 7 to 19 gestational weeks, a crucial period for cortical neuron specification and migration. HAR1F is co-expressed with reelin, a product of Cajal–Retzius neurons that is of fundamental importance in specifying the six-layer structure of the human cortex. HAR1 and the other human accelerated regions provide new candidates in the search for uniquely human biology."
The work suggests that protein-coding genes may not be the movers and shakers of human evolution. Rather, the non-coding 'dark matter' of genomes may harbour most of these vital changes, such as the set of 49 HAR regions - with HAR1 having accrued 18 changes in sequence since our divergence from chimpanzees, whereas only 1 or 2 substitutions would have been expected by chance.
Tuesday, August 22, 2006
Thus new neurons are not born in the adult human brain, and changes required for memory, learning, and injury repair must involve alterations or growth of connections between existing nerve cells.
Monday, August 21, 2006
Friday, August 18, 2006
Wallace argues that John Searles position ( "Mental phenomena are caused by neurophysiological processes in the brain and are themselves features of the brain" ) represents an "Illusion of Knowledge." a modern physicalist resistance to using introspection or accepting discoveries made with it, in favor of focus on behavioral and neural correlates of mental phenomena. He suggests an analogy with medieval theological resistance to Galileo, the refusal to use the telescope or accept discoveries made with it. He thinks that there should be a long delayed revolution in the mind sciences, to finally take up the challenges of William James ("Introspective Observation is what we have to rely on first and foremost and always..") and Wilhelm Wundt: ("The service which it [the experimental method] can yield consists essentially in perfecting our inner observation...."). He cites the 3,000 year old tradition of awareness training and introspection in Buddhism as one example of an appropriate approach to these goals (and in the discussion period he also mentions, Hindu, native american, and other meditative traditions.)
I'm entirely sympathetic with Wallace's goals and work, but I think that he's setting up a bit of a straw man in his extreme portrayals of physicalists or materialists (many of whom are quite open to any avenue of insight they can find). The problem I think is that his analogy with other scientific revolutions fails on the issue of universality and ability to reproduce basic introspective observations. Galileo's and Darwin's observations and measurements can be reproduced by anyone in any culture having appropriate equipment. In the period after William James' challenge and before the behaviorists' 50+ year death grip on progress in psychology a number of groups pursuing an introspective approach could not agree on many basic observations (Wallace commented on, but did not really address this issue in the discussion period). The introspective and meditative approaches associated with many different cultures and religions don't seem remotely close to yielding a unified introspective description of consciousness and our mental processes that transcends their cultural origins in the way that astronomy and biology do.
Still, I think that the Buddha was the first great human biologist in his astute descriptions of levels of human behavior that corresponds roughly to stages in the biological evolution of our own brains and behavior (see my "Beast Within" essay). The mutual reinforcement of ancient introspective and modern scientific traditions yields some robustness, and perhaps the prospect of an eventual union of materialistic and mentalistic perspectives. Perhaps this will yield the "consciousness meter," analogous to a telescope or microscope, than we are now lacking.
Wallace is president of The Santa Barbara Institute for Consciousness Studies. He trained for many years as a monk in Buddhist monasteries in India and Switzerland. He has taught Buddhist theory and practice in Europe and America since 1976 and has served as interpreter for numerous Tibetan scholars and contemplatives, including H. H. the Dalai Lama. After graduating summa cum laude from Amherst College, where he studied physics and the philosophy of science, he earned his M.A. and Ph.D. in religious studies at Stanford University. He has edited, translated, authored, and contributed to more than thirty books on Tibetan Buddhism, medicine, language, and culture, and the interface between science and religion. Dr. Wallace is a primary contributer to meditation research projects, including the Cultivating Emotional Balance project and the Shamatha project.
Wallace's published works include Choosing Reality: A Buddhist View of Physics and the Mind (Snow Lion, 1996), The Taboo of Subjectivity: Toward a New Science of Consciousness (Oxford, 2000), Buddhism and Science: Breaking New Ground (Columbia University Press 2003), Balancing the Mind: A Tibetan Buddhist Approach to Refining Attention (Snow Lion, 2005), and Genuine Happiness: Meditation as the Path to Fulfillment (John Wiley & Sons, 2005)
Thursday, August 17, 2006
A New York Times article today discusses a very practical use of noting subtle changes in this evolved facial musclulature. It is a key element of behavioral profiling increasingly being used at airports to discern potential terrorists. Work over many years by Paul Ekman at UCSF has generated a detailed catalog of these muscles and how they change in different contexts. He has developed a Facial Action Coding System (FACS) that is now widely used.
Here are some photos provided by Ekman showing several expressions. See if you can recognize them before looking at the captions.
Wednesday, August 16, 2006
Embodiment, the sense of being localized within one's physical body, is a fundamental aspect of the self. Recent evidence has started to show that self and body processing require two distinct brain mechanisms, with key loci in the temporoparietal junction (TPJ) - involved in self processing and multisensory integration of body-related information - and the extrastriate body area (EBA) - which responds selectively to human bodies and body parts. Arzy et al have used evoked potential mapping to show that activations in EBA and TPJ code differentially for embodiment and self location, because the location and timing of brain activation depended on whether mental imagery is performed with mentally embodied (EBA) or disembodied (TPJ) self location. In a second experiment, they showed that only EBA activation, related to embodied self location, but not TPJ activation, related to disembodied self location, was modified by the subjects' body position during task performance (supine or sitting). This suggests that embodied self location and actual body location share neural mechanisms.
Figure. To investigate embodiment and self location, subjects were asked to perform two mental-imagery tasks with respect to their own body in response to a schematic front- or back-facing human figure. In an own-body transformation task, (OBT task) subjects were asked to imagine themselves in the position and orientation of a schematic human figure, as shown on a computer screen (bottom row, the correct responses for each task are indicated under each stimulus) Either the right or left hand of the figure was marked, and subjects indicated which hand was marked. In a mirror task (MIR task), the same schematic human figure was shown, but subjects were instructed to imagine that the schematic figure (as shown on the computer screen) was their mirror reflection, as seen from their habitual point of view ( top row, the correct responses for each task are indicated under each stimulus).
Figure. Generators of mirror task (MIR. top row, were localized at the left EBA and of the own body transformation task (OBT, bottom row) at the right TPJ and left EBA
Figure. EBA. The mean (x, y) Talairach coordinates of the EBA are given for several neuroimaging studies. Note the similarity of EBA localization across studies, neuroimaging techniques, and behavioral tasks.
Tuesday, August 15, 2006
"Over the past 20 years, the percentage of U.S. adults accepting the idea of evolution has declined from 45% to 40% and the percentage of adults overtly rejecting evolution declined from 48% to 39%. The percentage of adults who were not sure about evolution increased from 7% in 1985 to 21% in 2005...Regardless of the form of the question, one in three American adults firmly rejects the concept of evolution, a significantly higher proportion than found in any western European country...the structure and beliefs of American fundamentalism historically differ from those of mainstream Protestantism in both the United States and Europe. The biblical literalist focus of fundamentalism in the United States sees Genesis as a true and accurate account of the creation of human life that supersedes any scientific finding or interpretation. In contrast, mainstream Protestant faiths in Europe (and their U.S. counterparts) have viewed Genesis as metaphorical and--like the Catholic Church--have not seen a major contradiction between their faith and the work of Darwin and other scientists...the evolution issue has been politicized and incorporated into the current partisan division in the United States in a manner never seen in Europe or Japan. In the second half of the 20th century, the conservative wing of the Republican Party has adopted creationism as a part of a platform designed to consolidate their support in southern and Midwestern states--the "red" states. In the 1990s, the state Republican platforms in seven states included explicit demands for the teaching of "creation science". There is no major political party in Europe or Japan that uses opposition to evolution as a part of its political platform...The broad public acceptance of the benefits of science and technology in the second half of the 20th century allowed science to develop a nonpartisan identification that largely protected it from overt partisanship. That era appears to have closed."
(By the way, in my July 20 post on involvement of the Locus Ceruleus in the retrieval of emotional memories I inexplicably neglected to mention that this cluster of nerve cells in the lower brain synthesizes noradrenaline (norepinephrine). Its axons, which project to the amygdala and other cortical areas, can 'spritz' large areas of the cortex during arousal, to enhance both the storage and retrieval of emotional memories.)
McGaugh gives a simplified graphic to summarize the main idea:
Figure - Schematic representation of modulation of memory consolidation by emotional arousal-induced release of adrenal stress hormones and noradrenergic activation of the amygdala. Emotional arousal activates the release of noradrenaline in the basolateral amygdala as well as the release of adrenal stress hormones. The stress hormones then provide increased and sustained noradrenergic activation in the amygdala. The amygdala activation modulates memory consolidation via projections to other brain systems processing memory. (Credit TICS)
Sunday, August 13, 2006
In their Report "On making the right choice: The deliberation-without-attention effect" (17 Feb., p. 1005), A. Dijksterhuis and colleagues reported the intriguing finding that when participants had to choose among four cars on the basis of various attributes, a period of conscious reflection worsened performance. They took this as evidence that complex choices are better when made unconsciously. A close examination of their methods, however, suggests a less startling interpretation.
Because of the easily confusable statements about the four cars, the 4-min period of reflection would cause considerable memory interference and leave participants utterly confused (was it the Hatsdun that had good handling and the Kaiwa no cupholders, or the other way round?). Memory research in the Bartlettian tradition has revealed many examples of such self-generated interference (1). The unconscious group made their decision after a similar 4-min period filled with a distractor task. Knowing that they would have no further opportunity for reflection prior to being required to make their choice, these individuals probably just made their decision at the end of the study period based on their overall impression of which car was best. This alternative account makes a simple and testable prediction, namely, that memory recall will be worse in the conscious condition.
An interesting but unnoted aspect of the findings was that the deliberation group chose the best car on only about 25% of occasions, exactly at chance. Does conscious deliberation yield no more than random results? The alternative account suggested here offers an explanation: It must have been because these individuals were faced with an insurmountable memory challenge and were completely confused about which attributes went with which car.
In any event, the decision problem presented in this study is very unlike the way we normally deliberate about a problem. When choosing between cars, we don't expend effort struggling to recall their attributes; we familiarize ourselves with the relevant attributes during the information search stage, and if we can't recall some attribute, we find it out. Dijksterhuis et al.'s findings would be altogether more compelling if they were replicated in a situation in which the 4-min deliberation period was spent studying the cars' attributes. But the likelihood is that under such circumstances, the best alternative would be selected by close to 100% of participants.
Reference 1. H. L. Roediger, E. T. Bergman, M. L. Meade, in Bartlett, Cognition and Culture, A. Saito, Ed. (Routledge, London, 2000), pp. 115-134.
David R. Shanks
Department of Psychology
University College London
London WC1E 6BT, UK
In our work on the "Deliberation-without-attention" effect, we found that, under complex decision circumstances, unconscious thinkers made better decisions than conscious deliberators. Conscious deliberators suffer from the low memory capacity of consciousness, which renders it impossible for them to take into account substantial amounts of information simultaneously. Unconscious thinkers, on the other hand, are not negatively affected by such capacity constraints. Shanks offers alternative explanations for our findings for both conscious deliberators and unconscious thinkers.
Shanks argues that our conscious thinkers may have faced memory problems. However, memory problems are not causing the effects we see. We have shown that even when the statements are presented in blocks (i.e., first all information on car A, then on car B, etc.), conscious deliberation still produces poor results (1). In addition, we have shown that even when people do have all the information at hand during conscious deliberation, it still produces poor results (2).
Shanks's suggestion that unconscious thinkers simply stick to the initial decision they made immediately after processing the information is not correct. In other experiments (1-3), we have compared unconscious thinkers with people who made decisions immediately after having received all the information, and unconscious thinkers performed better. Unconscious thought does lead to changes in preference, and it does so for the better.
Shanks also notes that under complex conditions, decisions made by conscious deliberators are no better than chance. Although conscious deliberation itself cannot be said to be random, the decisions produced by conscious deliberation are under some circumstances not superior to randomly generated decisions. There are moderators at work here, of course (e.g., expertise). Thus, the idea that conscious deliberation before making decisions is always good is simply one of those illusions consciousness creates for us.
Finally, Shanks observed that our experiments do not reflect the way people normally make decisions. This is true, as is usually the case with lab experiments. However, that is exactly the reason we included two field studies in our Report. In the field studies, people made real decisions with real consequences. These studies also confirmed the "deliberation-without-attention" hypothesis.
References 1. A. Dijksterhuis, J. Pers. Soc. Psychol. 87, 586 (2004). 2. A. Dijksterhuis, Z. van Olden, J. Exp. Soc. Psychol., in press. 3. A. Dijksterhuis, L. F. Nordgren, Pers. Psychol. Sci. 1, 95 (2006).
Maarten W. Bos
Loran F. Nordgren
Rick B. van Baaren
Department of Psychology
University of Amsterdam
Roetersstraat 15, 1018 WB
Amsterdam, the Netherlands
Friday, August 11, 2006
The term 'undermind' hasn't caught on, and the subsequent excellent book "The Wayward Mind" reverts to using the term "unconscious". "The Wayward Mind" is a history of human attempts to explain the unconscious mind, from ancient descriptions of the 'underworld' to the theories of modern neuroscience.
Here are (clipped and truncated) some lines from pp 348-352 of "Wayward Mind" that I like:
"What we call our ‘self’ is an agglomeration of both conscious and unconscious ingredients: cans, needs, dos, oughts, thinks….these constructions hold out an overwhelming temptation: to assume that the “I” is the same in all of them… so that instead of having an intricate web of things that make me Me, I have to create a single imaginary hub around which they all revolve, to which they all refer…the attempt to keep this fiction going, to ‘hold it together’ can become quite tiring and bothersome… If “I” am essentially reasonable, if I imagine that my zones of control – over my own feelings for example – are wider and more robust than they are, then I am going to get in a tangle trying to ‘control myself.’ If I have decided that who I am is clever, attractive, athletic, stable, creating the hub of “I” locks everything together and prevents it moving. It stops Me expanding to include the unconscious, or graciously shrinking to accommodate old age. I can’t enjoy my waywardness, nor see it as an intrinsic part of ME….All the evidence is that a more relaxed attitude toward the bounds of self makes for a richer, easier and more creative life. Perhaps, after all, waywardness in all its forms is in need not so much of explanation, but of a mystified but friendly welcome. We can explain it if we wish, and the brain is beginning to a reasonable job. But the need to explain, when not motivated by the dispassionate curiosity of the scientist, is surely a sign of anxiety: of the desire to tame with words that which is experienced as unsettling.. "
Thursday, August 10, 2006
At any rate, a report from Buck's laboratory (Nature 442, 645-650,10 August 2006) now finds mouse pheromone receptors in the lining of the nose, rather than the vomeronasal organ, and genes encoding this family of receptors are found also in humans and fish.
Figure legend: Digoxigenin-labelled antisense RNA probes for the mouse Taar genes indicated were hybridized to coronal sections of mouse olfactory epithelium. Each Taar probe hybridized to mRNA in a small percentage of OSNs scattered in selected olfactory epithelial regions. Credit: Nature Magazine
From the abstract: "these receptors, called 'trace amine-associated receptors' (TAARs), ... like odorant receptors... are expressed in unique subsets of neurons dispersed in the epithelium... at least three mouse TAARs recognize volatile amines found in urine: one detects a compound linked to stress, whereas the other two detect compounds enriched in male versus female urine—one of which is reportedly a pheromone. The evolutionary conservation of the TAAR family suggests a chemosensory function distinct from odorant receptors. Ligands identified for TAARs thus far suggest a function associated with the detection of social cues."
It remains to be seen whether activating or eliminating any of these TAAR receptors alters mouse behavior, and this needs to be demonstrated before moving on to possible human studies.
Wednesday, August 09, 2006
In some ways it is like shooting fish in a barrel. When giving his decision at the trial in which the school board in Dover, Pennsylvania, was challenged for including intelligent design in the biology curriculum (see Nature 439, 6–7;2006), federal judge John Jones described the argument that intelligent design is science as a "breathtaking inanity". His ruling is reprinted in part at the end of the book.
A recent election in Kansas has returned control of the State Board of Education to moderates who plan to reverse the redefinition of science attempted by the previous conservative board. Intelligent design advocates also have recently received setbacks in Ohio and Pennsylvania, but will certainly not give up their crusade.
Tuesday, August 08, 2006
The data suggest that preweanling pups have two odor-shock learning circuits, with maternal presence providing suppression of stress-induced corticosterone release and engaging the odor-shock circuit for odor preference learning supporting infant-mother attachment. The data suggest a way in which the functional maturation of brain development may be disrupted by stress.. The mother's ability to modify fear learning circuitry may provide clues to abusive attachment and predisposition for mental illness and altered emotional expression later in life. The validity of an animal model of abusive attachment is strengthened by the wide phylogenetic representation of abusive attachment, which has been documented in chicks, infant dogs, rodents and nonhuman primates.
Monday, August 07, 2006
"Human choices are remarkably susceptible to the manner in which options are presented. This so-called "framing effect" represents a striking violation of standard economic accounts of human rationality, although its underlying neurobiology is not understood. We found that the framing effect was specifically associated with amygdala activity, suggesting a key role for an emotional system in mediating decision biases. Moreover, across individuals, orbital and medial prefrontal cortex activity predicted a reduced susceptibility to the framing effect. This finding highlights the importance of incorporating emotional processes within models of human choice and suggests how the brain may modulate the effect of these biasing influences to approximate rationality."
From the brief review of this article by Miller in the same issue of Science, one example of framing:
Faced with a decision between two packages of ground beef, one labeled "80% lean," the other "20% fat," which would you choose? The meat is exactly the same, but most people would pick "80% lean." The language used to describe options often influences what people choose, a phenomenon behavioral economists call the framing effect. The Martino et al. experiments look directly at brain activity correlating with this effect.
The experiments used a novel financial decision-making task. Participants (20 university students or graduates) received a message indicating the amount of money that they would initially receive in that trial (e.g., "You receive £50"). Subjects then had to choose between a "sure" option and a "gamble" option presented in the context of two different frames. The "sure" option was formulated as either the amount of money retained from the initial starting amount (e.g., keep £20 of the £50; "Gain" frame) or as the amount of money lost from the initial amount (e.g., lose £30 of the £50; "Loss" frame). Subjects - who performed the task while inside an fMRI scanner! - were risk-averse in the Gain frame, tending to choose the sure option over the gamble option and were risk-seeking in the Loss frame, preferring the gamble option.
The amygdala (A, in the figure) was relatively more activated when subjects chose in accordance with the frame effect. When subjects made decisions that ran counter to their general behavioral tendency enhanced activity in the anterior cingulate cortex was observed (C, in the figure). This suggests an opponency between two neural systems, with ACC activation consistent with the detection of conflict between predominantly "analytic" response tendencies and a more "emotional" amygdala-based system.
Decreased susceptibility to the framing effect correlated with enhanced activity in the orbital and medial prefrontal cortex, specifically in the right orbitofrontal cortex (A, in the figure). The findings support a model in which the OMPFC evaluates and integrates emotional and cognitive information, thus underpinning more "rational" (i.e., description-invariant) behavior.
The framing bias occurs because "individuals incorporate a potentially broad range of additional emotional information into the decision process. In evolutionary terms, this mechanism may confer a strong advantage, because such contextual cues may carry useful, if not critical, information. Neglecting such information may ignore the subtle social cues that communicate elements of (possibly unconscious) knowledge that allow optimal decisions to be made in a variety of environments. However, in modern society, which contains many symbolic artifacts and where optimal decision-making often requires skills of abstraction and decontextualization, such mechanisms may render human choices irrational."
Saturday, August 05, 2006
The graphic shows the types of complex movement elicited by long-duration microstimulation. The maps of motor cortex regulating these movements are a bit complex to show in this posting.
Figure: Complex movements elicited by long-duration microstimulation. (A–C) Three types of complex movements evoked by long-duration stimulation within motor cortex. Complex movements elicited by long-duration microstimulation occur across multiple joints. (A) Reaching movement characterized by rostral displacement of the elbow and shoulder, without change in wrist configuration. (B) Retraction characterized by caudal displacement of the elbow and forepaw. (C) Grasping movement characterized by contraction of all digit joints simultaneously. Credit: PNAS.
Friday, August 04, 2006
And, in a bit of a non-sequitur: "The only comfort I’ve had from these disturbing trends is another recent story in The Times. Joyce Wadler reported that women in places like the Hamptons are still bedding down with the hired help. R. Couri Hay, the society editor of Hamptons magazine, celebrated rich women’s tendency to sleep with their home renovators..."Nobody knows,” he said. “The contractor isn’t going to tell because the husband is writing the check, the wife isn’t going to tell, and you get a better job because she’s providing a fringe benefit. Everybody wins.”...Thank God somebody is standing up for traditional morality."
Thursday, August 03, 2006
The gender debate: science promises an honest investigation of the world
- Department of Psychology, Harvard University, Cambridge, Massachusetts 02138, USA
Ben Barres's Commentary article "Does gender matter?" (Nature 442, 133–136; 2006) misrepresents my position.
In my book The Blank Slate (Allen Lane, London, 2002), and in a published debate (http://www.edge.org/3rd_culture/debate05/debate05_index.html), I reviewed a large empirical literature showing differences in mean and variance in the distributions of talents, temperaments and life priorities among men and women. Given these differences, some favouring men, some women, it is unlikely that the proportions of men and women in any profession would be identical, even without discrimination. That is probably one of several reasons that the sex ratio tips towards women in some scientific disciplines (such as my own, developmental psycholinguistics) and towards men in others. Barres renders this conclusion as "a whole group of people is innately wired to fail" — an egregious distortion.
Barres claims that I have denied that sex discrimination is a significant factor in professional life, whereas I have repeatedly stated the opposite, and indeed provided a jacket endorsement for Virginia Valian's book Why So Slow? (MIT Press, Cambridge, 1998) that summarized the evidence.
As for encouraging women in science: in my experience, students of both sexes are attracted to science because it promises an honest investigation into how the world works, an alternative to the subjectivity, simplistic dichotomies and moralistic name-calling that characterize politics and personal quarrels. Let's hope Barres's Commentary article does not discourage them.
Readers are encouraged to add their comments to the Ben Barres Commentary on the Nature News Blog at: http://blogs.nature.com/news/blog/2006/07/
A recent entry by J. B. Engelmann discusses a paper by Beaver et al. that examines the relationship between a personality trait, reward sensitivity, and activity of the brain reward system measured by functional magnetic resonance imaging. A study like this is relevant to understanding the over-consumption of appetizing high-caloric foods that has contributed to the dramatic increase in obesity within the past 20 years, making obesity a top 10 global health threat. Here are some clips from the review and article:
Figure - A highly simplified schematic diagram outlines the connections between central nodes in the brain reward system (modified from Berridge and Robinson, 2003). Animal as well as human neuroimaging studies have implicated this network in the hedonic and motivational effects of natural rewards and drugs of abuse, such as food and amphetamine. AMYG, Amygdala; NAC, nucleus accumbens; OFC, orbitofrontal cortex; VP, ventral pallidum; VTA/SN, ventral tegmental area/substantia nigra.
Beaver et al. showed that reward sensitivity, as assessed by the Behavioral Inhibition Scale/Behavioral Activation Scale, predicted neural responses to pictures of appetizing foods in the network of the brain regions outlined in the Figure. Functional magnetic resonance imaging, in conjunction with a blocked experimental design, was used to record blood oxygenation-level dependent (BOLD) responses while participants passively viewed pictures of foods from four different categories...The authors found increased activation in orbitofrontal cortex (appetizing vs nonfood objects) and bilateral ventral striatum (appetizing vs bland foods). Interestingly, there was a dissociation between left and right orbitofrontal cortex such that appetizing food stimuli activated the left orbitofrontal cortex, whereas disgusting food stimuli activated the right orbitofrontal cortex.
Beaver et al. provide an important link between human behavioral research that has demonstrated an association between trait reward sensitivity and unhealthy eating habits and animal research implicating the reward network in hyperphagia and increased intake of high-caloric foods. Their findings thus offer a possible explanation for why some individuals overeat compulsively. It will be interesting to establish a more direct link between compulsive overeating and responsivity of the reward system, for instance by correlating activity in the reward system in response to images depicting appetizing foods and body mass index. Finally, an abundance of parallels between obesity and drug addiction points to similarities in the underlying brain mechanisms and neural adaptations that accompany these two conditions
Wednesday, August 02, 2006
Our entire brain is recycled about every two months, and different components of the synapses that transmit information between nerve cells replace themselves, molecular for molecule, on a time scale of hours to days. All of these synapses and the intricate network of trillions of connections that they form have been crafted by our experience to make us who we are. How can all this remain stable when the large molecules that make synapses seem to be boiling, falling apart nearly as soon as they are made?
Synapses turn out to be reflecting a living confluence of top-down and bottom-up pressures.. (Bottom up: gene or RNA expression patterns remembering what the state of a synapse should be; top down: a constant replaying, or jangling trace, that helps keep labile synapses stabilized). The information is out there in the whole system and it is making the synaptic patterns we observe.
"This kind of topsy-turvey picture can only be resolved by taking a more holistic view of the
brain as the organ of consciousness. The whole shapes the parts as much as the parts shape
the whole. No component of the system is itself stable but the entire production locks together
to have stable existence. This is how you can manage to persist even though much of you is
being recycled by day if not the hour."
Tuesday, August 01, 2006
And, speaking of sounds, I might mention the totally unrelated point that I am starting to put some of my piano recordings and videos from this summer on my website.
Graphic credit, copyright: NYTimes