Monday, July 31, 2006
"Humans in the industrialized world have undergone a form of evolution that is unique not only to humankind, but unique among the 7,000 or so generations of humans who have ever inhabited the earth. The difference does not involve changes in genes, as far as is known, but changes in the human form. It shows up in several ways, from those that are well known and almost taken for granted, like greater heights and longer lives, to ones that are emerging only from comparisons of health records. The biggest surprise emerging from the new studies is that many chronic ailments like heart disease, lung disease and arthritis are occurring an average of 10 to 25 years later than they used to. There is also less disability among older people today, according to a federal study that directly measures it. And that is not just because medical treatments like cataract surgery keep people functioning. Human bodies are simply not breaking down the way they did before. Even the human mind seems improved. The average I.Q. has been increasing for decades, and at least one study found that a person’s chances of having dementia in old age appeared to have fallen in recent years. The proposed reasons are as unexpected as the changes themselves. Improved medical care is only part of the explanation; studies suggest that the effects seem to have been set in motion by events early in life, even in the womb, that show up in middle and old age."
"In 1900, 13 percent of people who were 65 could expect to see 85. Now, nearly half of 65-year-olds can expect to live that long. People even look different today. American men, for example, are nearly 3 inches taller than they were 100 years ago and about 50 pounds heavier."
"Today’s middle-aged people are the first generation to grow up with childhood vaccines and with antibiotics. Early life for them was much better than it was for their parents, whose early life, in turn, was much better than it was for their parents. And if good health and nutrition early in life are major factors in determining health in middle and old age, that bodes well for middle-aged people today. Investigators predict that they may live longer and with less pain and misery than any previous generation."
There is also the concern, however, that obesity could lead to so much diabetes and heart disease that life expectancy could level off or even decline within the first half of this century.
Graphic: credit and copyright, N.Y. Times
Friday, July 28, 2006
Figure: left superior temporal gyrus activity associated with listening to the artificial language conditions (compared with the random syllables condition) during the speech stream exposure task was significantly correlated with participants’ ability to discriminate words that occurred in the artificial languages. Credit: J. Neuroscience
These findings provide a neural signature of on-line word segmentation in the mature brain and an initial model with which to study developmental changes in the neural architecture involved in processing speech cues during language learning.
Thursday, July 27, 2006
Tuesday, July 25, 2006
Some remarkable experiments were started in the former Soviet Union in 1959 by Dmitri Belyaev, who decided to study the genetics of domestication and find what qualities were selected for by the neolithic farmers who developed most major farm species about 10,000 years ago. He decided to select for a single criterion: tameness. Starting by breeding silver foxes from the wild, after only eight generations animals that would tolerate human presence became common, and after 40 years and the breeding of 45,000 foxes, a group had emerged that were as tame and as eager to please as a dog. The tame silver foxes had begun to show white patches on their fur floppy ears, rolled tails and smaller skulls, like many other domesticated species. They also exhibited the unusual ability of dogs to understand human gestures (something Chimpanzees can't manage at all). Belyaev also bred a parallel colony of vicious foxes, but realizing that genetics can be better studied in smaller animals, he started working with local wild rats. In only sixty generations separate breeds of very tame and very ferocious rats were obtained. Paabo's laboratory in Germany is now crossing the tame and aggressive strains to find genetic sites that correlate with these behaviors. Such sites could then be examined in tame and aggressive individuals in other mammalian species, including humans... Perhaps an important part of homminid evolution was a human self-domestication that involved ostracizing (blocking the breeding of) individuals who were too aggressive.
The article by Dean in the same NYTimes issue provides a review of recent books on the clash between religion and science, and the debate over whether faith in God can coexist with faith in the scientific method. Professors of either faith or science acknowledge that they cannot prove that God either does or does not exist. Evolutionary psychological explanation of why religious belief seems to be universal among Homo sapiens are still "just-so" stories, very far from being proved.
The book by Lewis Wolpert "Six Impossible Things Before Breakfast: The Evolutionary Origins of Belief" (published in England, due in the U.S. in January) looks quite interesting:
"Dr. Wolpert writes about the way people think about cause and effect, citing among other work experiments on how we reason, how we assess risk, and the rules of thumb and biases that guide us when we make decisions. He is looking into what he calls “causal belief” — the idea that events or conditions we experience have a cause, possibly a supernatural cause.
Human reasoning is “beset with logical problems that include overdependence on authority, overemphasis on coincidence, distortion of the evidence, circular reasoning, use of anecdotes, ignorance of science and failures of logic,” he writes. And whatever these traits may say about acceptance of religion, they have a lot to do with public misunderstanding of science.
So, he concludes, “We have to both respect, if we can, the beliefs of others, and accept the responsibility to try and change them if the evidence for them is weak or scientifically improbable.”
This is where the scientific method comes in. If scientists are prepared to state their hypotheses, describe how they tested them, lay out their data, explain how they analyze their data and the conclusions they draw from their analyses — then it should not matter if they pray to Zeus, Jehovah, the Tooth Fairy, or nobody.
Their work will speak for itself."
"Learning the value of options in an uncertain environment is central to optimal decision making. The anterior cingulate cortex (ACC) has been implicated in using reinforcement information to control behavior. Here we demonstrate that the ACC's critical role in reinforcement-guided behavior is neither in detecting nor in correcting errors, but in guiding voluntary choices based on the history of actions and outcomes. ACC lesions did not impair the performance of monkeys (Macaca mulatta) immediately after errors, but made them unable to sustain rewarded responses in a reinforcement-guided choice task and to integrate risk and payoff in a dynamic foraging task. These data suggest that the ACC is essential for learning the value of actions."
Here is a graphic (credit: Ann Thomson, Nature Neuroscience) in an accompanying review of this work by Haydn and Platt.
Monkeys with lesions in the anterior cingulate cortex (ACC) correct errors but fail to maintain the new rewarded behavior. (a) Medial view of the right hemisphere in the macaque. Shading, location of the lesion in the ACC. (b) Behavioral responses of monkeys with ACC lesions in experiment 1. After one action—in this case, lift—was rewarded for 25 consecutive trials, the rewarded action was switched—in this case, to turn. Following an unrewarded lift response, lesioned monkeys switched to turning, but could not sustain this response on subsequent trials. Intact monkeys, however, had no difficulty with this task. Similar lesion-induced disruptions in behavioral performance were found in a reward probability matching task in a second experiment.
Monday, July 24, 2006
"He hit me first" provides an acceptable rationale for doing that which is otherwise forbidden. Both civil and religious law provide long lists of behaviors that are illegal or immoral — unless they are responses in kind, in which case they are perfectly fine...a punch thrown second is legally and morally different than a punch thrown first....That’s why participants in every one of the globe’s intractable conflicts — from Ireland to the Middle East — offer the even-numberedness of their punches as grounds for exculpation.
The problem with the principle of even-numberedness is that people count differently...In a study conducted by William Swann and colleagues at the University of Texas, pairs of volunteers played the roles of world leaders who were trying to decide whether to initiate a nuclear strike. The first volunteer was asked to make an opening statement, the second volunteer was asked to respond, the first volunteer was asked to respond to the second, and so on. At the end of the conversation, the volunteers were shown several of the statements that had been made and were asked to recall what had been said just before and just after each of them...The results revealed an intriguing asymmetry: When volunteers were shown one of their own statements, they naturally remembered what had led them to say it. But when they were shown one of their conversation partner’s statements, they naturally remembered how they had responded to it...
What seems like a grossly self-serving pattern of remembering is actually the product of two innocent facts. First, because our senses point outward, we can observe other people’s actions but not our own. Second, because mental life is a private affair, we can observe our own thoughts but not the thoughts of others. Together, these facts suggest that our reasons for punching will always be more salient to us than the punches themselves — but that the opposite will be true of other people’s reasons and other people’s punches...Examples aren’t hard to come by. Shiites seek revenge on Sunnis for the revenge they sought on Shiites; Irish Catholics retaliate against the Protestants who retaliated against them; and since 1948, it’s hard to think of any partisan in the Middle East who has done anything but play defense. In each of these instances, people on one side claim that they are merely responding to provocation and dismiss the other side’s identical claim as disingenuous spin. But research suggests that these claims reflect genuinely different perceptions of the same bloody conversation.
If the first principle of legitimate punching is that punches must be even-numbered, the second principle is that an even-numbered punch may be no more forceful than the odd-numbered punch that preceded it. Legitimate retribution is meant to restore balance, and thus an eye for an eye is fair, but an eye for an eyelash is not. When the European Union condemned Israel for bombing Lebanon in retaliation for the kidnapping of two Israeli soldiers, it did not question Israel’s right to respond, but rather, its “disproportionate use of force.” It is O.K. to hit back, just not too hard.
Research shows that people have as much trouble applying the second principle as the first. In a study conducted by Sukhwinder Shergill and colleagues at University College London, pairs of volunteers were hooked up to a mechanical device that allowed each of them to exert pressure on the other volunteer’s fingers.
The researcher began the game by exerting a fixed amount of pressure on the first volunteer’s finger. The first volunteer was then asked to exert precisely the same amount of pressure on the second volunteer’s finger. The second volunteer was then asked to exert the same amount of pressure on the first volunteer’s finger. And so on. The two volunteers took turns applying equal amounts of pressure to each other’s fingers while the researchers measured the actual amount of pressure they applied.
The results were striking. Although volunteers tried to respond to each other’s touches with equal force, they typically responded with about 40 percent more force than they had just experienced. Each time a volunteer was touched, he touched back harder, which led the other volunteer to touch back even harder. What began as a game of soft touches quickly became a game of moderate pokes and then hard prods, even though both volunteers were doing their level best to respond in kind.
Each volunteer was convinced that he was responding with equal force and that for some reason the other volunteer was escalating. Neither realized that the escalation was the natural byproduct of a neurological quirk that causes the pain we receive to seem more painful than the pain we produce, so we usually give more pain than we have received.
Research teaches us that our reasons and our pains are more palpable, more obvious and real, than are the reasons and pains of others. This leads to the escalation of mutual harm, to the illusion that others are solely responsible for it and to the belief that our actions are justifiable responses to theirs.
None of this is to deny the roles that hatred, intolerance, avarice and deceit play in human conflict. It is simply to say that basic principles of human psychology are important ingredients in this miserable stew. Until we learn to stop trusting everything our brains tell us about others — and to start trusting others themselves — there will continue to be tears and recriminations in the wayback.
Friday, July 21, 2006
This self-undermining is a stereotype effect, of the sort that has been documented it in many groups. Other studies have shown that women perform less well on math exams after reading that men tend to perform better on them. Similarly, white men perform less well when they are told that they are competing in math against Asian students.
Thursday, July 20, 2006
A Right amygdala. C Parahippocampus gyrus
A. Locus ceruleus.
Credit: J. Neuroscience
Wednesday, July 19, 2006
Tuesday, July 18, 2006
Free Will, Free Won't, or Neither? A refinement of Libet's work on the conscious control of spontaneous actions.
Lau et al. have now done a more nuanced version of LIbet's experiments. In a previous paper they showed that, when participants were required to estimate the onset of their intentions using Libet's procedure, the activity in the presupplementary motor area (pre-SMA) was enhanced ~228 msec before motor execution. In their most recent work they show that when participants were required to estimate the onset of their motor executions (instead of their intentions), the activity in the cingulate motor area was enhanced. This latter condition, judged to be more natural and have less task-demanding instructions. The perceived onset of intention could be as late as ~120 msec before the motor execution . "Together, these findings raise the question of whether the conscious control of spontaneous action can be done within a much shorter time window than we had expected, or whether, as suggested by Wegner (The illusion of conscious will Cambridge, MA: MIT Press, 2002), our impression of conscious control is simply illusory."
I think Wegner has it right. His book, and his interpretation of our sense of agency as an after the fact ' emotion of authorship' is a must-read for anyone interested in issues of conscious volition.
Monday, July 17, 2006
Take for example, chapter 5, ''Evolution, Karma, and the world of sentience' While it is quite extraordinary that someone in his position has learned so much, it is also not surprising that he seems to be unaware of work that counters many of his perceived shortcomings of "Darwinian evolutionary theory."
pg 104 "that mutations..take place naturally is unproblematic..that they are purely random strikes me as unsatisfying. It leaves open the question of whether this randomness is best understood as an objective feature of reality or better understood as indicating some kind of hidden causality."
This doesn't compute for me. Ionizing cosmic radiation hitting a nucleotide and altering its replication is random, as are a number of low frequency errors made by enzymic processes involved in replication. We at least have a handle on what we mean by random. There are countless examples of how statistically small random changes can lead to complex results (like eyes, or different kinds of hormone and neurotransmitter receptors). "Hidden causality' , on the other hand, is a complete deus ex machina, or wild card, with no presently known means of evaluation within a materialistic scientific world view. If something pops up, great, but until then......
pg 104, "For modern science, at least from a philosophical point of view, the critical divide seems to be between inanimate matter and the origin of living organisms, while for Buddhism the critical divide is between non-sentient matter and the emergence of sentient beings." Aren't we talking about apples and oranges? I'm not understanding the usefulness of trying so hard to unify things, as (on pg. 111) "On the whole, I think the Darwinian theory...gives a fairly coherent account of the evolution of human life on earth. At the same time, I believe that karma can have a central role in understanding the origination of Buddhism calls "sentience", through the media of energy and consciousness."
pg. 115 "I find it [Darwinian account] leaves one crucial area unexamined, the origin of sentience." Virtually all descriptions of the evolution of the nervous system (Dennett's in "Consciousness Explained", for example) view the increasingly complexity of the nervous system - and the gradient of increasing sentience, consciousness, or whatever - as Darwinian adaptations that increase survival fitness of the organism.
pg. 114 "I feel that this inability or unwillingness fully to engage the question of altruism is perhaps the most important drawback of Darwinian...." There are now abundant models of how 'selfish' genes and organisms can generate altruistic behaviors. There is even a recent computer model of simple automata (agents with a limited set of receptors and elementary actions) that evolve various cooperative strategies. (Nature, 20:1041, 2006). See also my 5/26/06 post on "Cooperation, Punishment, and the Evolution of Human Institutions"
Anyway, enough. I won't ramble on. He really is an extraordinary guy. I totally support the idea that buddhist psychological insight offers some correlates with modern cognitive neuroscience, as between Buddha's foundations of mindfulness and steps in the evolution of the brain (mentioned in my "Beast Within" essay at dericbownds.net).
Saturday, July 15, 2006
It is interesting that studies on several European, Canadian, and American families have found genetic changes that correlate with reading disorders, or dyslexia, independent of general cognitive performance. Fisher and Francks, in Trends in Cognitive Sciences, 10:250 (2006), provide an overview of four prominent examples (genes DYX1C1, KIAA0319, DCDC2, and ROBO1). These are not "genes for reading". None are specific to reading-related neuronal circuits, or even to the human brain. They do have intriguing roles in neuronal migration or connectivity. Individual genes do not specify behavioral outputs, cognitive skill, or even particular neural circuits. They "influence brain development and function interactively by affecting processes such as proliferation and migration of neurons, programmed cell-death, axonal pathfinding, connectivity, levels of neurotransmitters/receptors, and so on."
Friday, July 14, 2006
Thursday, July 13, 2006
CREDIT: COURTESY TED BRADER, graphic from Science Magazine. Cueing emotion: In Brader's enthusiasm experiment, one ad contained hopeful images and music while the other relied on the narration and less evocative imagery. (Both ads used the same positive script, here: "There's good news in your neighborhood. The future looks bright for a generation of young people.") The fear experiment compared the effects of the same unevocative imagery with those of threatening images and dissonant music. (In the negative narration for this pair, "It's happening right now in your neighborhood. A generation of young people is in danger.")
Wednesday, July 12, 2006
One explanation that has been proposed is a maternal immunization hypothesis. "When a mother is carrying her first son, the placental barrier protects each from exposure to the other’s proteins. But inevitable mixing of blood upon delivery will expose the mother for the first time to male-specific proteins..., including those encoded on the Y chromosome. If her immune system produces antibodies to these proteins, then the placenta may actively transport those antibodies (indeed, all IgGs) to subsequent offspring in utero, potentially affecting development of later-born sons, but not later-born daughters."
Tuesday, July 11, 2006
Credit: Science Magazine and Mona Lisa Chanda
When two mice had their paws injected with different amounts of formalin, which would induce different levels of licking behavior, the high formalin mouse licked less and the low formalin animal licked more, indicating that their behavior was influenced by their neighbor's status bidirectionally. Emotional contagion is an automatic primitive kind of empathy (human babies cry on hearing other babies cry, regardless of cause), it does not require understanding what others are experiencing, and is distinct from altruism. So far there is no evidence for these more advanced behaviors in mice.
Monday, July 10, 2006
Credit: Nature Neuroscience. The figure, from an accompanying review by Hedden and Gabrieli indicates some of the cortical regions associated with focused and lapsed attention. The arrows indicate reciprocal functional connections between prefrontal and parietal regions, and top-down modulation of occipital sensory regions by the prefrontal cortex. IFG, right inferior frontal gyrus; TPJ, temporal-parietal junction.
Sunday, July 09, 2006
Saturday, July 08, 2006
The roots of social intelligence. Fellowship. Foxes bred to be tame are keenly tuned in to human behavior. From Science Magazine, Credit: Irene Plyusnia, Photo Courtesy Of Brian Hare.
Friday, July 07, 2006
Localization of nucleus accumbens (A) and orbital frontal cortex (C) activation to reward.
Credit: Journal of Neuroscience
Thursday, July 06, 2006
Credit: Nature Magazine
The small (wrasse) fish is a cleaner of its client (bream) fish. It removes parasites, but actually prefers eating the clients mucus, which is not in the client's best inrest (i.e. is non-cooperative). Bshary and Grutter found that eavesdropping clients (who observed cleaners working on other clients) spent more time next to 'cooperative' than 'unknown cooperative level' cleaners, which shows that clients engage in image-scoring behaviour. Furthermore, trained cleaners learned to feed more cooperatively when in an 'image-scoring' than in a 'non-image-scoring' situation.
Wednesday, July 05, 2006
recognition for positive emotion (happiness) increased.
Credit: J. Neuroscience
Changes in both ERP (over the time course 40–450 ms after stimulus) and fMRI measures over age. Happiness relative to neutral showed a decrease in activity over the medial prefrontal region (shown in blue), which was most apparent for neural activity elicited during the early phase of processing (40–150 ms after stimulus). In response to fear, in contrast, there was an increase in activity over the medial prefrontal cortex with age (shown in red), which ERPs showed was most apparent for neural activity occurring in the later phase of the time course (180–450 ms after stimulus).
Fear elicited corresponding increases in medial prefrontal activation, apparent during the later (180–450 ms) controlled phase of processing. In contrast, medial prefrontal activation to happiness attenuated over age, apparent in the early, automatic (within 150 ms) phase of the time course. These changes indicate that processing resources are shifted from the automatic phase of stimulus appraisal toward a greater allocation during the controlled phase of stimulus evaluation. The authors propose that this shift in resources supports better selective control of reactions to negative, particularly threat-related stimulation and allows positive responses to proceed without restraint. Their observation that this shift in processing of negative versus positive emotion predicted better emotional wellbeing with older age supports the view that it contributes to an increasingly adaptive regulation of emotion.
The authors propose that life experience and changing motivational goals may drive plasticity in the medial prefrontal brain systems to increase selective control over the balance of negative and positive emotion, with the consequence of improving emotional wellbeing.
"The motivation to achieve better emotional control in older adults may come from the increasing awareness of one’s mortality and the desire to maximize the meaningfulness of environmental events and input, over and above the need for acquisition. With repeated emotional experiences over the lifespan, humans may learn to be more selective about which input is likely to provide quality positive outcomes as opposed to cause distress. Consistent with this view, older adults are more selective about their social activities and tend to prioritize quality rather than quantity."
Tuesday, July 04, 2006
I hope someone out there might explain this to me....
Monday, July 03, 2006
Sunday, July 02, 2006
An article by Amy Harmon in the June 15 N.Y.Times provides a nice table summary of a few of the genes known to influence behavior in humans and other animals:
INSIG2 - Obesity - A common gene variant that is associated with significantly increased risk of becoming fat among the more than 25 million Americans who carry it. Herbert et al. (2006) "A Common Genetic Variant Associated with Adult and Childhood Obesity". Science 312:279-283.
neuroD2 - Risk-taking - Mice lacking neuroD2 have a greatly reduced sense of fear. Variants of the human version of this gene may lead to risk-taking behaviors. Lin et al. "The dosage of neuroD2 transcription factor regulates amygdala development and emotional learning" Proceedings of the National Academy of Science 41:14877-14882
CYP2A6 - Nicotine Addiction - People with certain forms of this gene smoke more and are more likely to become addicted to cigarettes. Tailoring treatments based on which form of CYP2A6 a person has may help him or her quit. Minematsu et al. (2006) "Limitation of cigarette consumption by CYP2A6*4, *7 and *9 polymorphisms" European Respiratory Journal 27:289-292. Malaiyandi et al. (2006) "Impact of CYP2A6 genotype on pretreatment smoking behavioral and nicotine levels and usage of nicotine replacement therapy". Molecular Psychiatry (2006): 400–409.
AVPR1a and SLC6A4 - Dance talent - Variants of these genes are correlated with creative dance performance. Bachner-Melman et al. "AVPR1a and SLC6A4 Gene Polymorphisms Are Associated with Creative Dance Performance". PLoS Genetics 1(3): e42
DRD2 - Anorexia - Variants of this receptor for the neurotransmitter dopamine have been preliminarily linked to the risk of developing anorexia. Bergen et al. (2005) "Association of Multiple DRD2 Polymorphisms with Anorexia Nervosa" Neuropsychopharmacology 30, 1703-1710.
DRD4 - Sexual desire - Another dopamine receptor gene that is linked in this study with sexual desire and performance. Zion et al. (2006) "Polymorphisms in the dopamine D4 receptor gene (DRD4) contribute to individual differences in human sexual behavior: desire, arousal and sexual function". Molecular Psychiatry (published online ahead of print)
fruitless - Sexual orientation - Male and female fruit flies make different forms of this gene. Males carrying the female gene do not court females. Females carrying the male gene are attracted to other females. Demir and Dickson (2005). "fruitless Splicing Specifies Male Courtship Behavior in Drosophila" Cell 121:785-794.
Saturday, July 01, 2006
Also the Brain Connection aimed more at general public.
And, Brain explorer.
A site with many personal psychology and personality tests that you can take.
Links to a number of cognitive neuroscience sites.
Recent news in cognitive neuroscience.