Antidepressant effects of exercise - a mechanism

Here is an interesting bit from Hunsberger et al. in Nature Medicine, which suggests that a nerve growth factor pathway might be a target for antidepressant drug development (exercise might do the same thing, but depressed people usually aren't that keen on working out):

Exercise has many health benefits, including antidepressant actions in depressed human subjects, but the mechanisms underlying these effects have not been elucidated. We used a custom microarray to identify a previously undescribed profile of exercise-regulated genes in the mouse hippocampus, a brain region implicated in mood and antidepressant response. Pathway analysis of the regulated genes shows that exercise upregulates a neurotrophic factor signaling cascade that has been implicated in the actions of antidepressants. One of the most highly regulated target genes of exercise and of the growth factor pathway is the gene encoding the VGF nerve growth factor, a peptide precursor previously shown to influence synaptic plasticity and metabolism. We show that administration of a synthetic VGF-derived peptide produces a robust antidepressant response in mice and, conversely, that mutation of VGF in mice produces the opposite effects. The results suggest a new role for VGF and identify VGF signaling as a potential therapeutic target for antidepressant drug development.

GENES R US

This clip from the Jan. 20 issue of Science:

Personal genomics revved into high gear last year thanks to DNA chips that make it possible to cheaply scan the entire genome (Science, 21 December 2007, p. 1842). You can track the flood of new discoveries at SNPedia (www.snpedia.com), a Web site run by two biotech veterans in Bethesda, Maryland, that catalogs SNPs culled from the literature.

SNPs are single-nucleotide polymorphisms: single-base variations in DNA that researchers are tying to traits and disease risks. Browse by medical conditions (77 so far) and discover, for example, that carrying two copies of the T version of a SNP called rs2273535 raises your risk of colon cancer by 50%; another SNP, rs6152, is associated with baldness. Visitors can also search by genetically influenced drug reactions (48) and genes (128). There are links to relevant papers and sites (including James Watson's and J. Craig Venter's respective genomes) and to blogs by people who are sending their DNA to a lab to be "SNP chipped." The site is also a wiki, which means anyone can contribute.

The site "could be a very valuable research tool," says computational biologist Mark Daly of the Broad Institute in Cambridge, Massachusetts. "It will be great to see how this develops."

A Debussy Ballade - music for the start of the week

The only downside of being in Ft. Lauderdale FL. (sunny, 81 degress on Saturday) versus Madison, WI. (-7 degress, cloudy) is that my Steinway B grand piano stays in Madison. I have now installed a credible Steinway upright in the Ft. Lauderdale condo and have decided to continue on it the sort of video recordings I had been doing in Madison. I may re-record this piece on the better piano when I get back to Madison in the spring.

The bouncer in the brain...

In the January issue of Nature Neuroscience a review with the title of this post by Awh & Vogel discusses experiments by McNab & Klingberg that may explain why there are significant differences between individuals in working memory, which is known to be limited to about three or four items. Individual differences in this memory capacity correlate robustly with measures of fluid intelligence and scholastic aptitude. The experiments explore the idea that variations in the efficiency with which information is selected to fill this limited workspace are involved. From Awh and Vogel:

One perspective on individual differences in memory capacity views variation in terms of the number of 'slots' that are available for short-term storage. However, apparent capacity differences might also be explained by variations in the efficiency with which information is selected to fill this limited workspace. A useful analogy for understanding the difference between these two ideas is the difference between the space that is available in an exclusive nightclub and the effectiveness of the bouncer who grants admission. From this perspective, high-capacity individuals may have a better bouncer rather than a larger nightclub...brain imaging evidence from McNab and Klingberg implicates a specific neural region that may serve as the bouncer for the mind.

This hypothesis is consistent with a growing body of evidence that shows tight links between attention and working memory. Some theorists have even suggested that they are essentially the same mechanism. This viewpoint is supported by the strong overlap in the cortical areas that are active during attention and working-memory tasks, as well as evidence that directly implicates attention in the active maintenance of information in working memory. Furthermore, an individual's working-memory capacity is highly predictive of his or her performance on a wide range of attention tasks

Here is the abstract from McNab and Klingberg:

Our capacity to store information in working memory might be determined by the degree to which only relevant information is remembered. The question remains as to how this selection of relevant items to be remembered is accomplished. Here we show that activity in the prefrontal cortex and basal ganglia preceded the filtering of irrelevant information and that activity, particularly in the globus pallidus, predicted the extent to which only relevant information is stored. The preceding frontal and basal ganglia activity were also associated with inter-individual differences in working memory capacity. These findings reveal a mechanism by which frontal and basal ganglia activity exerts attentional control over access to working memory storage in the parietal cortex in humans, and makes an important contribution to inter-individual differences in working memory capacity.

Meditation Research

The Mind and Life Institute offers a quarterly bibliography with short descriptions of research work done of the effects of mindfulness-based cognitive therapy.

Pinker on the 'moral instinct'

It would have been nice to put a discussion of Pinker's NY Times Magazine article alongside the post on Metzinger's essay "There are no moral facts" but I didn't get around to it in time. Pinker is an exceptionally bright and clear writer. Even so, a bit of nit-picking can't be resisted, a few of his sentences have hidden land mines. Take for example:

...dissecting moral intuitions is no small matter. If morality is a mere trick of the brain, some may fear, our very grounds for being moral could be eroded. Yet as we shall see, the science of the moral sense can instead be seen as a way to strengthen those grounds, by clarifying what morality is and how it should steer our actions.

A continuous drumbeat throughout this blog has been to make the point that even our sense of having a purposeful "I" is a 'mere trick of the brain' (See also The "I" Illusion). A damned useful one, to be sure, that has resulted in a our dominance as a species on this planet. Seen in the light of evolution, an evolved moral sense can also be viewed as a yet more refined way of passing on or genes, and influencing the competition between groups of humans that has driven recent human evolution. Pinker's "how morality should steer our actions" flirts with the "naturalistic fallacy" (because this is what our biology gives us, it is the way things should be.) That "should" is relevant to passing on our genes, not to any ultimate criteria for morality. Metzinger's essay nails it:

...all we have to go by are the contingent moral intuitions evolution has hard-wired into our emotional self-model. If we choose to simply go by what feels good, then our future is easy to predict: It will be primitive hedonism and organized religion.

Or, take this gem from Pinker's article:

Though no one has identified genes for morality, there is circumstantial evidence they exist. The character traits called “conscientiousness” and “agreeableness” are far more correlated in identical twins separated at birth (who share their genes but not their environment) than in adoptive siblings raised together (who share their environment but not their genes). People given diagnoses of “antisocial personality disorder” or “psychopathy” show signs of morality blindness from the time they are children.

The villain here is the phrase "genes for morality". By now, most popularizers have left behind phrases like this, because it implies a causality that does not exist. Genes are not for anything by themselves, but have an unfolding expression that requires vastly complex interactions with other genes and the environment. They can be "permissive of..." or "increase the probability of..." a particular outcome, but they don't run the show. This why the phrase "genes for X" (where X is any complex behavior) should not be used.

Pinker proceeds through of very elegant and structured review of moralization switches, reasoning and rationalizing (including examples such as the well known "Trolley Problem" - for other examples see MindBlog's 'morality' category in the left column of the web page your are viewing.)

One of his best lines is: "When psychologists say “most people” they usually mean “most of the two dozen sophomores who filled out a questionnaire for beer money.”

Further topics include the idea of a universal morality, varieties of moral experience, and the genealogy of morals. He does a nice discussion of the five spheres of moral behavior that are shared by humans and many animals living in groups, suggesting ancient evolutionary origins of the behaviors (doing harm, fairness, community, authority, purity).

My favorite section in the esay is "Is morality a figment", where Pinker partially, but not completely addresses the first issue I raised above. Here is a clip, on where moral reasons might come from:

They certainly aren’t in the physical world like wavelength or mass. The only other option is that moral truths exist in some abstract Platonic realm, there for us to discover, perhaps in the same way that mathematical truths (according to most mathematicians) are there for us to discover. On this analogy, we are born with a rudimentary concept of number, but as soon as we build on it with formal mathematical reasoning, the nature of mathematical reality forces us to discover some truths and not others. (No one who understands the concept of two, the concept of four and the concept of addition can come to any conclusion but that 2 + 2 = 4.) Perhaps we are born with a rudimentary moral sense, and as soon as we build on it with moral reasoning, the nature of moral reality forces us to some conclusions but not others.

Moral realism, as this idea is called, is too rich for many philosophers’ blood. Yet a diluted version of the idea — if not a list of cosmically inscribed Thou-Shalts, then at least a few If-Thens — is not crazy. Two features of reality point any rational, self-preserving social agent in a moral direction. And they could provide a benchmark for determining when the judgments of our moral sense are aligned with morality itself.

One is the prevalence of nonzero-sum games. In many arenas of life, two parties are objectively better off if they both act in a nonselfish way than if each of them acts selfishly. ... Any neutral observer, and you and I if we could talk it over rationally, would have to conclude that the state we should aim for is the one in which we both are unselfish. These spreadsheet projections are not quirks of brain wiring, nor are they dictated by a supernatural power; they are in the nature of things.

The other external support for morality is a feature of rationality itself: that it cannot depend on the egocentric vantage point of the reasoner. If I appeal to you to do anything that affects me — to get off my foot, or tell me the time or not run me over with your car — then I can’t do it in a way that privileges my interests over yours (say, retaining my right to run you over with my car) if I want you to take me seriously. Unless I am Galactic Overlord, I have to state my case in a way that would force me to treat you in kind. I can’t act as if my interests are special just because I’m me and you’re not, any more than I can persuade you that the spot I am standing on is a special place in the universe just because I happen to be standing on it.

Not coincidentally, the core of this idea — the interchangeability of perspectives — keeps reappearing in history’s best-thought-through moral philosophies, including the Golden Rule (itself discovered many times); Spinoza’s Viewpoint of Eternity; the Social Contract of Hobbes, Rousseau and Locke; Kant’s Categorical Imperative; and Rawls’s Veil of Ignorance. It also underlies Peter Singer’s theory of the Expanding Circle — the optimistic proposal that our moral sense, though shaped by evolution to overvalue self, kin and clan, can propel us on a path of moral progress, as our reasoning forces us to generalize it to larger and larger circles of sentient beings.

Exercise effects on brain and cognition

Hillman et al., provide an interesting review article (PDF here) that examines the positive effects of aerobic physical activity on cognition and brain function, at the molecular, cellular, systems and behavioral levels.

The results of a meta-analysis of the effects of fitness training on cognition showed that the benefits of fitness training on four different cognitive tasks were significant. As illustrated in the figure, fitness training has both broad and specific effects. The effects are broad in the sense that individuals in aerobic fitness training groups (represented by the red bars) showed larger fitness training effects across the different categories of cognitive processes illustrated on the x-axis. They are specific in the sense that fitness training effects were larger for some cognitive processes, in particular executive control processes, than for other cognitive processes.

Physical activity has been found to enhance cognition, with a selectively larger effect on executive control functions compared with other cognitive processes. Accordingly, brain structures that mediate executive functions would be expected to show disproportionate changes as a result of participation in physical activity. One such structure is the anterior cingulate cortex (ACC), which is part of the brain's limbic system and has connections with multiple brain structures that process sensory, motor, emotional and cognitive information. Two convergent lines of research indicate that physical activity exerts a substantial influence on the ACC and the concomitant executive processes that it mediates.

Permanent Reincarnation

Here are some clips from an interesting essay by science writer Tor Norretranders:

My body is not like a typical material object, a stable thing. It is more like a flame, a river or an eddie. Matter is flowing through it all the time. The constituents are being replaced over and over again...98 percent of the atoms in the body are replaced every year. 98 percent! Water molecules stays in your body for two weeks (and for an even shorter time in a hot climate), the atoms in your bones stays there for a few months. Some atoms stay for years. But almost not one single atom stay with you in your body from cradle to grave...What is constant in you is not material. An average person takes in 1.5 ton of matter every year as food, drinks and oxygen. All this matter has to learn to be you. Every year. New atoms will have to learn to remember your childhood.

These numbers has been known for half a century or more, mostly from studies of radioactive isotopes. Physicist Richard Feynman said in 1955: "Last week's potatoes! They now can remember what was going on in your mind a year ago."

But digital media now makes it possible to think of all this in a simple way. The music I danced to as a teenager has been moved from vinyl-LPs to magnetic audio tapes to CDs to Pods and whatnot. The physical representation can change and is not important — as long as it is there. The music can jump from medium to medium, but it is lost if it does not have a representation. This physics of information was sorted out by Rolf Landauer in the 1960'ies. Likewise, out memories can move from potato-atoms to burger-atoms to banana-atoms. But the moment they are on their own, they are lost.

We reincarnate ourselves all the time. We constantly give our personality new flesh. I keep my mental life alive by making it jump from atom to atom. A constant flow. Never the same atoms, always the same river. No flow, no river. No flow, no me...This is what I call permanent reincarnation: Software replacing its hardware all the time. Atoms replacing atoms all the time. Life. This is very different from religious reincarnation with souls jumping from body to body (and souls sitting out there waiting for a body to take home in).

Coevolution of choosiness and cooperation

An interesting modeling article by McNamara et al. suggests a novel evolutionary mechanism based on a positive coevolutionary feedback between cooperativeness and choosiness. If individuals vary in their degree of cooperativeness, and if they can decide whether or not to continue interacting with each other on the basis of their respective levels of cooperativeness, then cooperation can gradually evolve from an uncooperative state. When an individual's cooperativeness is used by other individuals as a choice criterion, there can be competition to be more generous than others (competetive altruism). The evolution of cooperation between non-relatives can then be driven by a positive feedback between increasing levels of cooperativeness and choosiness. In this model, individual behavioural differences are the key to the evolution of cooperation. Because the model does not invoke complex mechanisms such as negotiation behaviour, it can be applied to a wide range of species.

The model calculations use an infinite population where, in each of a discrete series of time steps (rounds), pairs of individuals engage in a game that can be described as a social dilemma. Each individual is characterized by two traits: a cooperativeness trait x, which specifies the amount of effort that the individual devotes to generating benefits available (at least in part) to its co-player; and a choosiness trait y, which specifies the minimum degree of cooperativeness that the focal individual is prepared to accept from its co-player. The traits x and y are genetically determined and are not adjusted in response to the co-player's behaviour. Thus, unlike in many models in which flexible effort adjustment is a key ingredient1, individuals in their model are consistent in their degree of cooperativeness.

Planned Obsolescence? The Four-Year Itch

Helen Fisher, author of "Why We Love" and an anthropology professor at Rutgers, has written a brief essay with the title of this post. She did a cross cultural survey of when divorces occur and found that divorces regularly peaked during and around the fourth year after wedding (no evidence for the commonly assumed seven year itch indicated in the graphic). Divorces peaked among couples in their late twenties. And the more children a couple had, the less likely they were to divorce: some 39% of worldwide divorces occurred among couples with no dependent children; 26% occurred among those with one child; 19% occurred among couples with two children; and 7% of divorces occurred among couples with three young. In trying to figure out so many men and women divorce during and around the 4-year mark; at the height of their reproductive years; and often with a single child, she had an "a ha" moment:

Women in hunting and gathering societies breastfeed around the clock, eat a low-fat diet and get a lot of exercise — habits that tend to inhibit ovulation. As a result, they regularly space their children about four years apart. Thus, the modern duration of many marriages—about four years—conforms to the traditional period of human birth spacing, four years.

Perhaps human parental bonds originally evolved to last only long enough to raise a single child through infancy, about four years, unless a second infant was conceived. By age five, a youngster could be reared by mother and a host of relatives. Equally important, both parents could choose a new partner and bear more varied young.

Her theory fits with data on other species:

Only about three percent of mammals form a pairbond to rear their young. Take foxes. The vixen's milk is low in fat and protein; she must feed her kits constantly; and she will starve unless the dog fox brings her food. So foxes pair in February and rear their young together. But when the kits leave the den in mid summer, the pairbond breaks up. Among foxes, the partnership lasts only through the breeding season. This pattern is common in birds. Among the more than 8,000 avian species, some 90% form a pairbond to rear their young. But most do not pair for life. A male and female robin, for example, form a bond in the early spring and rear one or more broods together. But when the last of the fledgling fly away, the pairbond breaks up... Like pair-bonding in many other creatures, humans have probably inherited a tendency to love and love again—to create more genetic variety in our young.

The neural control of vigor

An interesting article from Dolan's laboratory on the neural substrates of the motivation and vigor with which we perform actions. Their abstract lays it out clearly:

The vigor with which a participant performs actions that produce valuable outcomes is subject to a complex set of motivational influences. Many of these are believed to involve the amygdala and the nucleus accumbens, which act as an interface between limbic and motor systems. One prominent class of influences is called pavlovian–instrumental transfer (PIT), in which the motivational characteristics of a predictor influence the vigor of an action with respect to which it is formally completely independent. We provide a demonstration of behavioral PIT in humans, with an audiovisual predictor of the noncontingent delivery of money inducing participants to perform more avidly an action involving squeezing a handgrip to earn money. Furthermore, using functional magnetic resonance imaging, we show that this enhanced motivation was associated with a trial-by-trial correlation with the blood oxygenation level-dependent (BOLD) signal in the nucleus accumbens and a subject-by-subject correlation with the BOLD signal in the amygdala. Our data dovetails well with the animal literature and sheds light on the neural control of vigor.

Figure - The PIT paradigm used. Stage 1, In the pavlovian conditioning stage, participants are exposed to repeated pairings of the CS+ (a visual background and a sound) and a US (monetary reward of 20 pence), as well as presentations of a CS– that is not associated with reward. Here participants pressed a key to remove a patch that hid either a coin (CS+) or a coin with a superimposed red X (CS–). During the baseline CS, no patches were present; thus, there was no opportunity for reward. Each CS block lasted 12 s. Stage 2, During instrumental learning, participants were trained to squeeze a handgrip to obtain the same reward. Each block lasted 12 s. Stage 3, The critical PIT test took place under extinction and included presentation of the three CSs in a random order (here only the CS+ block is depicted). The participant was allowed to continue responding instrumentally.

Figure - Amygdala activity associated with PIT. Participants who showed a larger global PIT expressed enhanced bilateral amygdala activation. The bar graph shows, for the right amygdala and NAcc, mean parameter estimates for the correlation, across participants, of global PIT with the parameter estimate in each CS condition. Error bars represent the 90% confidence interval. *p <>

There are No Moral Facts - Metzinger

Here is a brief essay from one of my heroes, Thomas Metzinger, that I completely agree with - spiced up by an unrelated and gratuitous graphic on morality.

I have become convinced that it would be of fundamental importance to know what a good state of consciousness is. Are there forms of subjective experience which — in a strictly normative sense — are better than others? Or worse? What states of consciousness should be illegal? What states of consciousness do we want to foster and cultivate and integrate into our societies? What states of consciousness can we force upon animals — for instance, in consciousness research itself? What states of consciousness do we want to show our children? And what state of consciousness do we eventually die in ourselves?

2007 has seen the rise of an important new discipline: "neuroethics". This is not simply a new branch of applied ethics for neuroscience — it raises deeper issues about selfhood, society and the image of man. Neuroscience is now quickly transformed into neurotechnology. I predict that parts of neurotechnology will turn into consciousness technology. In 2002, out-of-body experiences were, for the first time, induced with an electrode in the brain of an epileptic patient. In 2007 we saw the first two studies, published in Science, demonstrating how the conscious self can be transposed to a location outside of the physical body as experienced, non-invasively and in healthy subjects. Cognitive enhancers are on the rise. The conscious experience of will has been experimentally constructed and manipulated in a number of ways. Acute episodes of depression can be caused by direct interventions in the brain, and they have also been successfully blocked in previously treatment-resistant patients. And so on.

Whenever we understand the specific neural dynamics underlying a specific form of conscious content, we can in principle delete, amplify or modulate this content in our minds. So shouldn’t we have a new ethics of consciousness — one that does not ask what a good action is, but that goes directly to the heart of the matter, asks what we want to do with all this new knowledge and what the moral value of states of subjective experience is?

Here is where I have changed my mind. There are no moral facts. Moral sentences have no truth-values. The world itself is silent, it just doesn’t speak to us in normative affairs — nothing in the physical universe tells us what makes an action a good action or a specific brain-state a desirable one. Sure, we all would like to know what a good neurophenomenological configuration really is, and how we should optimize our conscious minds in the future. But it looks like, in a more rigorous and serious sense, there is just no ethical knowledge to be had. We are alone. And if that is true, all we have to go by are the contingent moral intuitions evolution has hard-wired into our emotional self-model. If we choose to simply go by what feels good, then our future is easy to predict: It will be primitive hedonism and organized religion.

Listening with your visual cortex.

We experience our environment through simultaneous stimulation of several sensory channels. Watching a movie is usually a visual and auditory experience. This integration from different sensory modalities helps with stimulus detection and discrimination in noisy environments. A traditional views of brain organization has postulated strict parceling into unisensory and and then multisensory cortical levels. Romei et al. have now shown in humans that auditory information goes directly to the primary visual cortex, before higher levels of integration.

When subjects are instructed to detect simple stimuli (a briefly presented pure tone, a small white disk, or a combination of the two), and their reaction times (RTs) are measured, reaction RTs are significantly better for the audio-visual (AV) condition than for both unimodal conditions, indicating a behavioral facilitation effect for stimuli presented simultaneously in both modalities. Romei et al. gave brief trans-cranial magnetic stimultion (TMS) to occipital poles of the subjects' heads. TMS effects over visual cortex in a timeframe from 60 to 75 ms after sensory stimulus onset would suggest an interaction with feedforward processes, whereas later effects might be caused by feedback from higher cortical regions. Thus, varying the delay from 30 to 150 ms between TMS and the preceding sensory stimulation in different sensory modalities enabled them to determine the processing type (feedforward or feedback), as well as the critical timeframe of visual cortex involvement in stimulus processing.

Relative to TMS over a control site, reactions times (RTs) to unisensory visual stimuli were prolonged by TMS at 60–75 ms poststimulus onset (visual suppression effect), confirming stimulation of functional visual cortex. Conversely, RTs to unisensory auditory stimuli were significantly shortened when visual cortex was stimulated by TMS at the same delays (beneficial interaction effect of auditory stimulation and occipital TMS). No TMS-effect on RTs was observed for AV stimulation. A follow-up experiment showed that auditory input enhances excitability within visual cortex itself over a similarly early time-window (75–120 ms).

Face perception after no experience of faces

This work really nails down the fact that face processing is a special perceptual process and is organized as such at birth, as contrasted with having its origin in a more general-purpose perceptual system that becomes specialized after frequent visual experiences. Sugita has studied face perception in monkeys reared with no exposure to faces. Here is his abstract, and one figure from the paper:

Infant monkeys were reared with no exposure to any faces for 6–24 months. Before being allowed to see a face, the monkeys showed a preference for human and monkey faces in photographs, and they discriminated human faces as well as monkey faces. After the deprivation period, the monkeys were exposed first to either human or monkey faces for a month. Soon after, the monkeys selectively discriminated the exposed species of face and showed a marked difficulty in regaining the ability to discriminate the other nonexposed species of face. These results indicate the existence of an experience-independent ability for face processing as well as an apparent sensitive period during which a broad but flexible face prototype develops into a concrete one for efficient processing of familiar faces.

Figure: An infant monkey and her living circumstance. An infant monkey and a caregiver with (A) and without (B) a facemask. Both photos were taken after the face-deprivation period. (C) Toys placed in the monkey's home cage. (D) Decorations provided around the home cage.

We Differ More Than We Thought

This essay by Mark Pagel is worth passing on in its entirety:

The last thirty to forty years of social science has brought an overbearing censorship to the way we are allowed to think and talk about the diversity of people on Earth. People of Siberian descent, New Guinean Highlanders, those from the Indian sub-continent, Caucasians, Australian aborigines, Polynesians, Africans — we are, officially, all the same: there are no races.

Flawed as the old ideas about race are, modern genomic studies reveal a surprising, compelling and different picture of human genetic diversity. We are on average about 99.5% similar to each other genetically. This is a new figure, down from the previous estimate of 99.9%. To put what may seem like miniscule differences in perspective, we are somewhere around 98.5% similar, maybe more, to chimpanzees, our nearest evolutionary relatives.

The new figure for us, then, is significant. It derives from among other things, many small genetic differences that have emerged from studies that compare human populations. Some confer the ability among adults to digest milk, others to withstand equatorial sun, others yet confer differences in body shape or size, resistance to particular diseases, tolerance to hot or cold, how many offspring a female might eventually produce, and even the production of endorphins — those internal opiate-like compounds.

We also differ by surprising amounts in the numbers of copies of some genes we have. Modern humans spread out of Africa only within the last 60-70,000 years, little more than the blink of an eye when stacked against the 6 million or so years that separate us from our Great Ape ancestors. The genetic differences amongst us reveal a species with a propensity to form small and relatively isolated groups on which natural selection has often acted strongly to promote genetic adaptations to particular environments.

We differ genetically more than we thought, but we should have expected this: how else but through isolation can we explain a single species that speaks at least 7,000 mutually unintelligible languages around the World?

What this all means is that, like it or not, there may be many genetic differences among human populations — including differences that may even correspond to old categories of 'race' — that are real differences in the sense of making one group better than another at responding to some particular environmental problem. This in no way says one group is in general 'superior' to another, or that one group should be preferred over another. But it warns us that we must be prepared to discuss genetic differences among human populations.

Please Clap, Talk or Shout at Any Time

Bernard Holland reviews Kenneth Hamilton's book, “After the Golden Age,” a detailed reflection on concert behavior in the 19th and early 20th centuries published recently by Oxford University Press. Fascinating bits of information about a bygone era before our current time, when

Concertgoers like you and me have become part police officer, part public offender. We prosecute the shuffled foot or rattled program, the errant whisper or misplaced cough. We tense at the end of a movement, fearful that one of the unwashed will begin to clap, bringing shame on us all. How serious we look, and how absurd we are.

A number of fascinating facts:

...the silence at a London performance of Liszt’s “Dante” Symphony represented not rapt attention but audience distaste.
...hardly anybody played more than one movement of a Beethoven sonata at a time.
...Audience participation was taken for granted in the 1840s. The pianist Alexander Dreyschock was criticized for playing “so loud that it made it difficult for the ladies to talk,”

...Concerts were different back then. Liszt could get away with the radical idea of “one man, one recital,” but musical events were usually variety shows in the manner of vaudeville. The star pianist or violinist was just an occasionally recurring act in a parade of singers, orchestra players, quartets and trios. When Liszt did his solo acts, there was none of the march-on, march-off stage ritual of today. Liszt greeted patrons at the door, mingled in the audience and schmoozed with friend and stranger alike.

...Whole recitals also took place between acts of an opera or movements of a symphony. When Chopin played his E minor Piano Concerto in Warsaw in 1830, other pieces were inserted between the first two movements. Perhaps the most celebrated such interruption was at the 1806 premiere of Beethoven’s Violin Concerto in Vienna, where the soloist thrilled listeners by playing his violin upside down and on one string.

Regret

How do we feel about alternative versions of ourselves - lost possible selves, or the person we might have been? Benedict Carey writes a nice piece on this question. A few clips:

...Over the past decade and a half, psychologists have studied how regrets — large and small, recent and distant — affect people’s mental well-being. They have shown, convincingly though not surprisingly, that ruminating on paths not taken is an emotionally corrosive exercise. The common wisdom about regret — that what hurts the most is not what you did but what you didn’t do — also appears to be true, at least in the long run.

...young adults who scored high on measures of psychological well-being tended to think of regretted decisions as all their own — perhaps because they still had time to change course. By contrast, older people who scored highly tended to share blame for their regretted decisions. “I tried to reach out to him, but the effort wasn’t returned.”

...those who are able to talk or write about this lost future without sinking into despair or losing hope tend to have developed another quality, called complexity...an ability to incorporate various points of view into a recollection, to vividly describe the circumstances, context and other dimensions...that this knack for self-evaluation develops over time; it is a learned ability.

...therapists have long known the value of seeing regretted choices in the context of what has been gained as well as lost.

...the perspective from which people remember slights or mistakes can affect the memories’ emotional impact... reimagining painful scenes from a third-person point of view, as if seeing oneself in a movie, blunts their emotional sting and facilitates ... clearheaded self-perception.

Compensatory neural plasticity in aging human brains.

Recent imaging studies have shown that seniors exhibit stronger brain activation than younger controls during the execution of various motor tasks. Old subjects activate the same regions as their younger counterparts, but to a larger extent, and they also activate additional regions that are not observed in the young subjects.

Heuninckx et al. examine the underlying neural mechanisms of this "overactivation" by determining whether it reflects compensation for various neural/behavioral deficits (e.g., neurodegeneration, attentional problems, reduction in sensory function, etc.) or whether it is due to de-differentiation (a generalized nonfunctional spread of activity attributable to deficits in neurotransmission, which in turn causes a decrease in the signal-to-noise ratio in neural firing and a loss of neural specialization). They compared brain activity in 24 older adults and 11 young controls during the performance of rhythmical hand–foot coordination tasks, whereby both limbs moved either in the same (iso-directional) or in the opposite (non-isodirectional, NONISODIR in the figure below) direction. Previous behavioral work had shown convincingly that the non-isodirectional pattern is more difficult and is produced with lower accuracy and stability than the iso-directional pattern. Activation in dedicated brain regions was correlated with motor performance in the elderly. According to the compensation hypothesis, the underlying rationale was that the over-activation would be larger in good than in poor motor performers, with the effect being more pronounced in more (non-isodirectional) than less (iso-directional) demanding coordination tasks. Conversely, the de-differentiation hypothesis assumed overactivation to be larger in poor than in successful motor performers because of nonfunctional neural irradiation. Thus, positive correlations between brain activation and motor performance were considered to reflect compensation, and negative correlations were considered to reflect de-differentiation.

They found that that coordination resulted in activation of classical motor coordination regions and also higher-level sensorimotor and frontal regions in the elderly. A positive correlation between activation level in these latter regions and motor performance was observed. This performance enhancing additional recruitment is consistent with the compensation hypothesis and reflects neuroplasticity at the systems level in the aging brain.


Figure: (Click to enlarge). Statistical parametric maps representing significantly larger activation in the old compared with the young group during the NONISODIR coordination mode, resulting from the following contrast: (NONISODIR – rest)old versus (NONISODIR – rest)young. L, Left hemisphere; R, right hemisphere. White arrows indicate brain regions that exhibit a significant correlation between brain activity level and coordination performance, as identified by a whole-brain multiple regression analysis. The graphics display each subject's BOLD response with respect to the within-cluster peak activation as a function of the inverse of the phase error (1/AE), with the younger subjects in blue and the older subjects in red.

What have you changed your mind about?

The Edge.org Annual Question for 2008, addressed to a select group of their choice of the intellectual elite, is "What have you changed your mind about? Why?" (I've done blog postings on the responses to questions of the two previous years: "What is your dangerous idea?" and "What are you optimistic about? Why?"

I started to do thumbnail summaries of the responses I thought worth passing on to you, but found that most were not very succinct, and sufficiently diffuse to make brief summary difficult. Then pack much less punch than the 'dangerous idea' responses. I recommend that you scroll through the responses yourself. I may focus on a few of them in subsequent posts.

Drunken flies get hypersexual - and gay

Sound familiar? Reminds me of similar behaviors after University of Wisconsin football games, when drunken guys who could not find an appropriate female object would go ahead with what was available - other guys. This news item by Heidi Ledford in Nature describes experiments by Lee et al. that:

...tested the effects of chronic alcohol exposure on sexual behaviour in the fruitfly Drosophila melanogaster. The researchers noted that male flies repeatedly exposed to ethanol vapour became less discriminate in their mate selection. The buzzed flies often courted fellow males, pursuing them around the cage while serenading with a traditional fruitfly courtship song played on vibrating wings.


[Figure: Love Chain, male fruit flies chase each other in a circle] Eventually, the lusty flies devolve into a courting frenzy. “You get a chain of males chasing each other,” says Heberlein, who was not associated with the study but has observed similar behaviour in her own unpublished work. In contrast, alcohol had little effect on mating in female fruitflies, which normally do not court their mates.

The findings suggest that the flies do not fundamentally change their sexual orientation, but rather get over-sexed. “Multiple alcohol exposures makes them essentially hypersexual,” says Heberlein. The mind-dulling effects of alcohol might also make it more of a challenge for male fruitflies to distinguish the gender of other flies in the crowd.

Because of the genetic tools available, fruitflies might be a good model system for probing the idea, suggested for humans, that the neurotransmitter dopamine is a link between sex and alcohol.