Thursday, January 31, 2008

Why men are at the top.

Helena Cronin presents an interesting idea about why men walk off with most of the top positions and prizes that sidesteps the usual assumption of average differences between men and women in innate talents, tastes and temperaments. She notes that there not only more Nobels, but also more dumbbells among men, and suggests that it is a fourth "T" that most decisively shapes the distinctive structure of male — female differences. Some clips from her essay:
That T is Tails — the tails of these statistical distributions. Females are much of a muchness, clustering round the mean. But, among males, the variance — the difference between the most and the least, the best and the worst — can be vast. So males are almost bound to be over-represented both at the bottom and at the top...Consider the mathematics sections in the USA's National Academy of Sciences: 95% male. Which contributes most to this predominance — higher means or larger variance? One calculation yields the following answer. If the sex difference between the means was obliterated but the variance was left intact, male membership would drop modestly to 91%. But if the means were left intact but the difference in the variance was obliterated, male membership would plummet to 64%. The overwhelming male predominance stems largely from greater variance...Similarly, consider the most intellectually gifted of the USA population, an elite 1%. The difference between their bottom and top quartiles is so wide that it encompasses one-third of the entire ability range in the American population, from IQs above 137 to IQs beyond 200. And who's overwhelmingly in the top quartile? Males. Look, for instance, at the boy:girl ratios among adolescents for scores in mathematical-reasoning tests: scores of at least 500, 2:1; scores of at least 600, 4:1; scores of at least 700, 13.1.

The legacy of natural selection is twofold: mean differences in the 3 Ts and males generally being more variable; these two features hold for most sex differences in our species and, as Darwin noted, greater male variance is ubiquitous across the entire animal kingdom...The upshot? When we're dealing with evolved sex differences, we should expect that the further out we go along the right curve, the more we will find men predominating. So there we are: whether or not there are more male dumbbells, there will certainly be — both figuratively and actually — more male Nobels.

Unfortunately, however, this is not the prevailing perspective in current debates, particularly where policy is concerned. On the contrary, discussions standardly zoom in on the means and blithely ignore the tails. So sex differences are judged to be small. And thus it seems that there's a gaping discrepancy: if women are as good on average as men, why are men overwhelmingly at the top? The answer must be systematic unfairness — bias and barriers. Therefore, so the argument runs, it is to bias and barriers that policy should be directed. And so the results of straightforward facts of statistical distribution get treated as political problems

Creationists launch 'science' journal

Oh my gawd........ a new Creationist 'scientific' journal. This from the Jan. 23 online Nature News:
Papers will be peer reviewed by those who “support the positions taken by the journal”, according to editor-in-chief Andrew Snelling, a geologist based in Brisbane, Australia.
The Answers Research Journal makes life simple. You start with the result you want, and work from there. Much more efficient than conventional science.

George Lakoff on Obama vs. Hillary

Here are some succinct points made by George Lakoff, who has written on the power of metaphors in politics, and the importance of 'framing' political debates.

Wednesday, January 30, 2008

Newborn humans: predisposition for biological motion

This work demonstrates that when we are born, we have an innate bias towards attending to motions characteristic of other living things. Newborn chickens do this also. The abstract, a figure, and a video from Simion et al. :
An inborn predisposition to attend to biological motion has long been theorized, but had so far been demonstrated only in one animal species (the domestic chicken). In particular, no preference for biological motion was reported for human infants of less than 3 months of age. We tested 2-day-old babies' discrimination after familiarization and their spontaneous preferences for biological vs. nonbiological point-light animations. Newborns were shown to be able to discriminate between two different patterns of motion (Exp. 1) and, when first exposed to them, selectively preferred to look at the biological motion display (Exp. 2). This preference was also orientation-dependent: newborns looked longer at upright displays than upside-down displays (Exp. 3). These data support the hypothesis that detection of biological motion is an intrinsic capacity of the visual system, which is presumably part of an evolutionarily ancient and nonspecies-specific system predisposing animals to preferentially attend to other animals.

Figure: Three sample frames taken from the animation sequences used in the study: the biological motion stimulus (i.e., the walking hen) (Top), the nonbiological motion stimulus (random motion) (Middle), and the inverted biological motion display (upside-down walking hen) (Bottom). Squares indicate the point-lights.

Songbirds also have mirror neurons.

Mirror neurons in humans and other primates fire both when a given action is either performed or observed (see the 'mirror neuron' category in the left column of this blog.) Now Prather et al. have found similar neurons in the swamp sparrow, which like humans depends on auditory experience to learn its vocal repertoire. These forebrain neurons are specialized for auditory-vocal monitoring and have virtually the same response to a given note sequence, whether performed or heard. They also innervate striatal structures important for song learning, raising the possibility that singing-related activity in these cells is compared to auditory feedback to guide vocal learning. Here is a graphic from a New and Views article on this work by Tchernichovski1 & Wallman in the same issue of Nature.

(click to enlarge) Figure legend: The neurons identified by Prather and colleagues could be involved in three sensorimotor processes. a, The delayed corollary discharge of song patterns can be simultaneously compared with auditory feedback of the bird's own song, allowing tuning. b, The auditory responses (in the mirroring neurons) to songs of a neighbour might be compared with the memory of the corollary discharge produced during singing. This might allow the bird to identify an imitation by that neighbour. c, Corollary discharges while singing might be compared with a memory of the mirroring neurons' response to the parent's song. The error may then feed back to the song generator and guide vocal learning during song development, in addition to guidance from auditory input during singing (lowest arrow).

Tuesday, January 29, 2008

More on the evils of multitasking.

In a comment below, MindBlog reader Gregory points to a great article in the Atlantic on the toxic mental effects of multitasking. I wanted to bring the link into this separate post so that more of you will see it. It is by culture/technology commentator Walter Kirn:
Neuroscience is confirming what we all suspect: Multitasking is dumbing us down and driving us crazy. One man’s odyssey through the nightmare of infinite connectivity

...Multitasking messes with the brain in several ways. At the most basic level, the mental balancing acts that it requires—the constant switching and pivoting—energize regions of the brain that specialize in visual processing and physical coordination and simultaneously appear to shortchange some of the higher areas related to memory and learning. We concentrate on the act of concentration at the expense of whatever it is that we’re supposed to be concentrating on.

What does this mean in practice? Consider a recent experiment at UCLA, where researchers asked a group of 20-somethings to sort index cards in two trials, once in silence and once while simultaneously listening for specific tones in a series of randomly presented sounds. The subjects’ brains coped with the additional task by shifting responsibility from the hippocampus—which stores and recalls information—to the striatum, which takes care of rote, repetitive activities. Thanks to this switch, the subjects managed to sort the cards just as well with the musical distraction—but they had a much harder time remembering what, exactly, they’d been sorting once the experiment was over.

Even worse, certain studies find that multitasking boosts the level of stress-related hormones such as cortisol and adrenaline and wears down our systems through biochemical friction, prematurely aging us. In the short term, the confusion, fatigue, and chaos merely hamper our ability to focus and analyze, but in the long term, they may cause it to atrophy.

The next generation, presumably, is the hardest-hit. They’re the ones way out there on the cutting edge of the multitasking revolution, texting and instant messaging each other while they download music to their iPod and update their Facebook page and complete a homework assignment and keep an eye on the episode of The Hills flickering on a nearby television.

Pinker et al. on the logic of indirect speech.

Pinker, Nowak, and Lee do an interesting perspectives article in PNAS that looks more rigorously at why we don't just blurt out what we mean, as in:
- Would you like to come up and see my etchings? [a sexual come-on]
- If you could pass the guacamole, that would be awesome. [a polite request]
- Nice store you got there. Would be a real shame if something happened to it. [a threat]
- We're counting on you to show leadership in our Campaign for the Future. [a solicitation for a donation]
- Gee, officer, is there some way we could take care of the ticket here? [a bribe]
Here is their abstract:
When people speak, they often insinuate their intent indirectly rather than stating it as a bald proposition. Examples include sexual come-ons, veiled threats, polite requests, and concealed bribes. We propose a three-part theory of indirect speech, based on the idea that human communication involves a mixture of cooperation and conflict. First, indirect requests allow for plausible deniability, in which a cooperative listener can accept the request, but an uncooperative one cannot react adversarially to it. This intuition is supported by a game-theoretic model that predicts the costs and benefits to a speaker of direct and indirect requests. Second, language has two functions: to convey information and to negotiate the type of relationship holding between speaker and hearer (in particular, dominance, communality, or reciprocity). The emotional costs of a mismatch in the assumed relationship type can create a need for plausible deniability and, thereby, select for indirectness even when there are no tangible costs. Third, people perceive language as a digital medium, which allows a sentence to generate common knowledge, to propagate a message with high fidelity, and to serve as a reference point in coordination games. This feature makes an indirect request qualitatively different from a direct one even when the speaker and listener can infer each other's intentions with high confidence.

More Retro Video

After last week's Disco flashback, I can't resist giving you a little more nostalgia (this ought to make you cringe)... The Partridge Family's "I think I love you" from their popular sitcom in the early 1970s.

Monday, January 28, 2008

Are you holding your breath?

I notice - if I am maintaining awareness of my breathing - that the breathing frequently stops as I begin a skilled activity such as piano or computer keyboarding. At the same time I can begin to sense an array of unnecessary (and debilitating) pre-tensions in the muscle involved. If I just keep breathing and noticing those tensions, they begin to release. (Continuing to let awareness return to breathing when it drifts is a core technique of mindfulness meditation). Several sources note that attending to breathing can raise one's general level of restfulness relative to excitation, enhancing parasympathetic (restorative) over sympathetic (arousing) nervous system activities. These personal points make me feel like passing on some excerpts from a recent essay which basically agrees with these points: "Breathtaking New Technologies," by Linda Stone, a former Microsoft VP and Co-Founder and Director of Microsoft's Virtual Worlds Group/Social Computing Group. It is a bit simplistic, but does point in a useful direction.
I believe that attention is the most powerful tool of the human spirit and that we can enhance or augment our attention with practices like meditation and exercise, diffuse it with technologies like email and Blackberries, or alter it with pharmaceuticals...but... the way in which many of us interact with our personal technologies makes it impossible to use this extraordinary tool of attention to our advantage...the vast majority of people hold their breath especially when they first begin responding to email. On cell phones, especially when talking and walking, people tend to hyper-ventilate or over-breathe. Either of these breathing patterns disturbs oxygen and carbon dioxide balance...breath holding can contribute significantly to stress-related diseases. The body becomes acidic, the kidneys begin to re-absorb sodium, and as the oxygen and CO2 balance is undermined, our biochemistry is thrown off.

The parasympathetic nervous system governs our sense of hunger and satiety, flow of saliva and digestive enzymes, the relaxation response, and many aspects of healthy organ function. Focusing on diaphragmatic breathing enables us to down regulate the sympathetic nervous system, which then causes the parasympathetic nervous system to become dominant. Shallow breathing, breath holding and hyper-ventilating triggers the sympathetic nervous system, in a "fight or flight" response...Some breathing patterns favor our body's move toward parasympathetic functions and other breathing patterns favor a sympathetic nervous system response. Buteyko (breathing techniques developed by a Russian M.D.), Andy Weil's breathing exercises, diaphragmatic breathing, certain yoga breathing techniques, all have the potential to soothe us, and to help our bodies differentiate when fight or flight is really necessary and when we can rest and digest.

I've changed my mind about how much attention to pay to my breathing patterns and how important it is to remember to breathe when I'm using a computer, PDA or cell phone...I've discovered that the more consistently I tune in to healthy breathing patterns, the clearer it is to me when I'm hungry or not, the more easily I fall asleep and rest peacefully at night, and the more my outlook is consistently positive...I've come to believe that, within the next 5-7 years, breathing exercises will be a significant part of any fitness regime.

Why you think that $100 bottle of wine is better...

This little bit of work notes the neural basis of some of our 'refined aesthetic preferences'...what your brain might be doing when you feel that something that costs more is better (even when you are unknowingly comparing identical items). Here is the abstract from Plassmann et al.:
Despite the importance and pervasiveness of marketing, almost nothing is known about the neural mechanisms through which it affects decisions made by individuals. We propose that marketing actions, such as changes in the price of a product, can affect neural representations of experienced pleasantness. We tested this hypothesis by scanning human subjects using functional MRI while they tasted wines that, contrary to reality, they believed to be different and sold at different prices. Our results show that increasing the price of a wine increases subjective reports of flavor pleasantness as well as blood-oxygen-level-dependent activity in medial orbitofrontal cortex, an area that is widely thought to encode for experienced pleasantness during experiential tasks. The paper provides evidence for the ability of marketing actions to modulate neural correlates of experienced pleasantness and for the mechanisms through which the effect operates.

Figure: Neural correlates of liking ratings. (A) Activity in the mOFC and the midbrain correlated with the reported pleasantness of the six liquids at degustationtime. (B) Correlationof pleasantness ratings and BOLD responses

Friday, January 25, 2008

The new commonwealth

Some interesting comments by Kevin Kelly on possible political consequences of the Wikipedia phenomenon, excerpted from his brief essay. He changed his initial assumption that an encyclopedia editable by anyone would be an impossibility. This commentary has a rather different spirit than yesterday's post on the internet phenomenon.
It has always been clear that collectives amplify power — that is what cities and civilizations are — but what's been the big surprise for me is how minimal the tools and oversight are needed. The bureaucracy of Wikipedia is relatively so small as to be invisible. It's the Wiki's embedded code-based governance, versus manager-based governance that is the real news. Yet the greatest surprise brought by the Wikipedia is that we still don't know how far this power can go. We haven't seen the limits of wiki-ized intelligence. Can it make textbooks, music and movies? What about law and political governance?

The reality of a working Wikipedia has made a type of communitarian socialism not only thinkable, but desirable. Along with other tools such as open-source software and open-source everything, this communtarian bias runs deep in the online world...In other words it runs deep in this young next generation. It may take several decades for this shifting world perspective to show its full colors. When you grow up knowing rather than admitting that such a thing as the Wikipedia works; when it is obvious to you that open source software is better; when you are certain that sharing your photos and other data yields more than safeguarding them — then these assumptions will become a platform for a yet more radical embrace of the commonwealth. I hate to say it but there is a new type of communism or socialism loose in the world, although neither of these outdated and tinged terms can accurately capture what is new about it.

The Wikipedia has changed my mind, a fairly steady individualist, and lead me toward this new social sphere. I am now much more interested in both the new power of the collective, and the new obligations stemming from individuals toward the collective. In addition to expanding civil rights, I want to expand civil duties. I am convinced that the full impact of the Wikipedia is still subterranean, and that its mind-changing power is working subconsciously on the global millennial generation, providing them with an existence proof of a beneficial hive mind, and an appreciation for believing in the impossible.

Immune system subjugation of the brain

Research on links between brain, behavior, and the immune system is expanding rapidly. It has long been known that depression lowers immunity, and Dantzer et al. offer a review of causality in the opposite direction: release of cytokines by the innate immune system during infection which in the short term triggers sickness behaviors in the long term can cause depression. Here is their abstract and a PDF.
In response to a peripheral infection, innate immune cells produce pro-inflammatory cytokines that act on the brain to cause sickness behaviour. When activation of the peripheral immune system continues unabated, such as during systemic infections, cancer or autoimmune diseases, the ensuing immune signalling to the brain can lead to an exacerbation of sickness and the development of symptoms of depression in vulnerable individuals. These phenomena might account for the increased prevalence of clinical depression in physically ill people. Inflammation is therefore an important biological event that might increase the risk of major depressive episodes, much like the more traditional psychosocial factors.

Thursday, January 24, 2008

Does the internet liberate or enslave us?

A book by Lee Siegel "Against the Machine," reviewed by Janet Maslin in the NY Times, and an essay by Nicholas Carr raise a related set of arguments that challenge the assumption that the internet is a liberating force, a force for freedom, diffusing power and information among the many, rather than the few. At the same time web traffic in increasing, it is becoming more centralized. Carr notes:
-During the five years from 2002 through 2006, the number of Internet sites nearly doubled, yet the concentration of traffic at the ten most popular sites nonetheless grew substantially, from 31% to 40% of all page views
-Google continues to expand its hegemony...In March 2006, the company's search engine was used to process a whopping 58% of all searches in the United States, according to Hitwise. By November 2007, the figure had increased yet again, to 65%. The results of searches are also becoming more, not less, homogeneous. Do a search for any common subject, and you're almost guaranteed to find Wikipedia at or near the top of the list of results.
-Executives of Yahoo and Sun Microsystems have recently predicted that control over the net's computing infrastructure will ultimately lie in the hands of five or six organizations.
-To what end will the web giants deploy their power? They will, of course, seek to further their own commercial or political interests by monitoring, analyzing, and manipulating the behavior of "users." ...What's different, in comparison to the physical world, is that acts of control are more difficult to detect.

Graphical depiction of the Internet as consisting of a dense core of 80 or so critical nodes surrounded by an outer shell of 5,000 sparsely connected, isolated nodes that are very much dependent upon this core. (Shai Carmi, Bar Ilan University)

Siegel deals with socially toxic effects of the internet. From Maslin's review, describing Siegle's account of Starbucks, as one is:
...surrounded by Internet zombies, laptop-addicted creatures who have so grievously lost their capacity for human interaction “that social space has been contracted into isolated points of wanting, all locked into separate phases of inwardness.”...the semblance of a shared Starbucks experience masks endemic computer-generated isolation, a condition that has prompted psychic and ethical breakdowns that go well beyond the collapse of community....why we are living so gullibly through what would have been the plot of a science-fiction movie 15 years ago. Why does the freedom promised by the Internet feel so regimented and constricting? Why do its forms of democracy have their totalitarian side? What happens to popular culture when its sole emphasis is on popularity? How have we gone “from ‘I love that thing he does!’ to ‘Look at all those page views!’ in just a few years”?

Remember Disco??

I saw this video (So Many Men, So Little Time - Miquel Brown) during happy hour at the local bar (Georgie's Alibi) several evenings ago and was totally transported back to my days of disco dancing in the late 1970's, early 1980's, getting hot and sweaty, tearing off the shirt, etc. The same moves at my current age would probably be life-threatening. I'll bet a number of you remember this kind of energy...

Wednesday, January 23, 2008

The myth of the mid-life crisis.

Here is an engaging article by Richard Freedman on the supposed crisis around age 50 (mainly in men) when the first signs of physical decline and the questions and doubts about one’s personal and professional accomplishments emerge.
..some find themselves seized by a seemingly irresistible impulse to do something dramatic, even foolish. Everything, it appears, is fair game for a midlife crisis: one’s job, spouse, lover — you name it.
Freedman outlines:
a garden-variety case of a middle-aged narcissist grappling with the biggest insult he had ever faced: getting older...But you have to admit that “I’m having a midlife crisis” sounds a lot better than “I’m a narcissistic jerk having a meltdown.”
Another source of the midlife 'crisis' :
...reaching a situation...of having to seriously take account of someone else’s needs, such as those of children, for the first time.
Further clips:
Why do we have to label a common reaction of the male species to one of life’s challenges — the boredom of the routine — as a crisis? True, men are generally more novelty-seeking than women, but they certainly can decide what they do with their impulses.

The main culprit, I think, is our youth-obsessed culture, which makes a virtue of the relentless pursuit of self-renewal. The news media abound with stories of people who seek to recapture their youth simply by shedding their spouses, quitting their jobs or leaving their families. Who can resist?..Most middle-aged people, it turns out, if we are to believe the definitive survey...Except, of course, for the few — mainly men, it seems — who find the midlife crisis a socially acceptable shorthand for what you do when you suddenly wake up and discover that you’re not 20 anymore.

Terror alerts kill more people than terrorists in the US?

I have long held the opinion, reinforced by this article in the NYTimes, that the absurd terror alert system devised by the department of "homeland security" kills more people than the potential terrorist threat, given that "the chances of the average person dying in America at the hands of international terrorists to be comparable to the risk of dying from eating peanuts, being struck by an asteroid or drowning in a toilet." The article describes studies on a cohort of 2,700 people studied before and after the Sept. 11 attack which indicate a correlation (which is not a cause) between expressed anxiety over a terrorist attack and subsequent cardiovascular ailments.

Tuesday, January 22, 2008

The Impressionable Brain

I want to pass on this essay by Marcel Kinsbourne, which is an interesting exegesis of the implication of mirror neuron systems in our brain, especially with respect to possibly making moot the issue of brain versus environmental effects:
When the phenomenon of "mirror neurons" that fire both when a specific action is perceived and when it is intended was first reported, I was impressed by the research but skeptical about its significance...I have come to realize that mirror neurons are not only less than meets the eye but also more. Instead of being a specific specialization, they play their role as part of a fundamental design characteristic of the brain; that is, when percepts are activated, relevant intentions, memories and feelings automatically fall into place.

That an individual is likely to act in the same ways that others act is seen in the documented benefit for sports training of watching experts perform. "Emotional contagion" occurs when someone witnesses the emotional expressions of another person and therefore experiences that mood state oneself. People's viewpoints can subtly and unconsciously converge when their patterns of neural activation match, in the total absence of argument or attempts at persuasion. When people entrain with each other in gatherings, crowds, assemblies and mobs, diverse individual views reduce into a unified group viewpoint.

People's views are surreptitiously shaped by their experiences, and rationality comes limping after, downgraded to rationalization. Once opinions are established, they engender corresponding anticipations. People actively seek those experiences that corroborate their own self-serving expectations. This may be why as we grow older, we become ever more like ourselves. Insights become consolidated and biases reinforced when one only pays attention to confirming evidence. Diverse mutually contradictory "firm convictions" are the result.

If I am correct in my changed views as to what mirror neurons stand for and how representation routinely merges perception, action, memory and affect into dynamic reciprocal interaction, these views would have a bearing on currently disputed issues. Whether an effect is due to the brain or the environment would be moot if environmental causes indeed become brain causes, as the impressionable brain resonates with changing circumstances. What we experience contributes mightily to what we are and what we become.

What people experience indeed changes their brain, for better and for worse. In turn, the changed brain changes what is experienced. Regardless of its apparent stability over time, the brain is in constant flux, and constantly remodels. Heraclitus was right: "You shall not go down twice to the same river". The river will not be the same, but for that matter, neither will you. We are never the same person twice. The past is etched into the neural network, biasing what the brain is and does in the present. William Faulkner recognized this: "The past is never dead. In fact, it's not even past".

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.


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 (, 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."

Monday, January 21, 2008

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.

Friday, January 18, 2008

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.

Thursday, January 17, 2008

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.

Wednesday, January 16, 2008

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 <>

Tuesday, January 15, 2008

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).

Monday, January 14, 2008

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.

Friday, January 11, 2008

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.


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 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.

Thursday, January 10, 2008

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 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.

Wednesday, January 09, 2008

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.

Love hangover - the sex peptide

A male, after copulation, has a particular interest in seeing that the female involved ceases further sexual activity that might dilute his genetic contribution. It turns out that male fruitflies don't have to stand by and guard their transferred genetic material — a sex peptide in their semen will do the job. This peptide leads to increased egg-laying by the mated female and behavioural changes that reduce the likelihood of her re-mating. Yapici et al. have now identified the receptor protein for this peptide. It functions in a subset of neurons implicated in other sex-related behaviors. The receptor is highly conserved across insect species, raising the possibility that it could be targeted to disrupt reproduction in insect pests or host-seeking behaviour in disease vectors. (There appears to be no evidence for such a mechanism in primates and humans!).

Tuesday, January 08, 2008

More on laughing rats...and human chanting?

This is a sequel to my March 20 and June 18, 2007, posts on laughing rats. Rats use ultrasonic communication, with 50-kHz vocalizations indicating an animal's positive subjective state. Wöhr and Schwarting now show that show that 50-kHz signals (either natural 50-kHz calls, which had been previously recorded from other rats, or artificial sine wave stimuli, which were identical to these calls with respect to peak frequency, call length and temporal appearance) can induce approach behaviors. The effect is more pronounced in juvenile rats. It is commonly assumed that humans have lost this mechanism, but I wonder if the powerful bonding emotions induced in groups of humans doing very low frequency vocal chants, which surely have harmonics in the 50-mHz range, might be a evolutionary derivative of this early mammalian behavior . Here are several Tibetan master chants offered by the free sound project. Do they chill you out?

The value of believing in free will.

Vohs and Schooler do an interesting experiment in which they ask whether believing in free will versus determinism influences moral behavior. I have free access only to the abstract of the article, so can not spell out the details of the experiments. Here is that abstract:
Does moral behavior draw on a belief in free will? Two experiments examined whether inducing participants to believe that human behavior is predetermined would encourage cheating. In Experiment 1, participants read either text that encouraged a belief in determinism (i.e., that portrayed behavior as the consequence of environmental and genetic factors) or neutral text. Exposure to the deterministic message increased cheating on a task in which participants could passively allow a flawed computer program to reveal answers to mathematical problems that they had been instructed to solve themselves. Moreover, increased cheating behavior was mediated by decreased belief in free will. In Experiment 2, participants who read deterministic statements cheated by overpaying themselves for performance on a cognitive task; participants who read statements endorsing free will did not. These findings suggest that the debate over free will has societal, as well as scientific and theoretical, implications.

A YouTube for ideas......

You might enjoy checking out this article by Tim Arango on a new website, Big Think, which appears to be a sort of combination of YouTube and Facebook for intellectuals.

Monday, January 07, 2008

Why can't we perform perfectly?

Some fascinating experiments by Tumer and Brainar on songbirds inform me on why I am not able to perform a completely learned and exhaustively practiced piano piece the same way each time I bang it out.... from the Nature Editor's review of their article:
Why is it that even the best-trained athletes and musicians cannot perform perfectly? One thought is that residual variability in performance is 'noise' that reflects fundamental limits on our ability to control our movements. Experiments using the exceptionally well-rehearsed songs of adult songbirds as a model point to an alternative explanation. Computerized monitoring of the apparently stereotyped songs of adult Bengalese finches revealed minuscule variations in performance. When the birds were given corrections each time the song varied beyond a certain limit, they rapidly learned to adapt their vocalizations. The implication is that once learned, songs can be maintained despite subtle changes to the vocal system due to factors such as ageing. So behavioural 'noise', rather than simply being a nuisance, may reflect experimentation by the nervous system to refine performance.
The abstract from Rumer and Brainar:
Significant trial-by-trial variation persists even in the most practiced skills. One prevalent view is that such variation is simply 'noise' that the nervous system is unable to control or that remains below threshold for behavioural relevance. An alternative hypothesis is that such variation enables trial-and-error learning, in which the motor system generates variation and differentially retains behaviours that give rise to better outcomes. Here we test the latter possibility for adult bengalese finch song. Adult birdsong is a complex, learned motor skill that is produced in a highly stereotyped fashion from one rendition to the next. Nevertheless, there is subtle trial-by-trial variation even in stable, 'crystallized' adult song. We used a computerized system to monitor small natural variations in the pitch of targeted song elements and deliver real-time auditory disruption to a subset of those variations. Birds rapidly shifted the pitch of their vocalizations in an adaptive fashion to avoid disruption. These vocal changes were precisely restricted to the targeted features of song. Hence, birds were able to learn effectively by associating small variations in their vocal behaviour with differential outcomes. Such a process could help to maintain stable, learned song despite changes to the vocal control system arising from ageing or injury. More generally, our results suggest that residual variability in well learned skills is not entirely noise but rather reflects meaningful motor exploration that can support continuous learning and optimization of performance.

Hope worse than Hopelessness

This short piece by Marina Krakovsky from the NY Times:
People often display a remarkable ability to adapt to adversity, bouncing back to their usual levels of happiness despite extreme hardships. But people don’t always rebound, and scientists have long wondered what factors might account for the difference. In a talk at Harvard in September, a team of researchers suggested that one obstacle to emotional recovery, oddly enough, is hope — the belief that your current hardship is temporary.

From the beginning, the investigators suspected that hope might sometimes be counterproductive: prisoners with life sentences but with the possibility of parole adapt less well to prison life, for example, than prisoners with life sentences without the possibility of parole. But the researchers sought another empirical test. Their choice: Colostomy patients. The research team, led by Peter Ubel, a physician at the University of Michigan, tracked people who had portions of their colons removed or bypassed, such that the patients couldn’t defecate normally. The condition is extremely unpleasant and leads many people to say they’d rather be dead, Ubel reports. But a colostomy isn’t always permanent. Some patients are likely to heal and have their bowels reconnected. Whether your colostomy is permanent depends on your condition, but were it up to the patient to choose, “almost anybody would choose temporary over permanent,” Ubel says.

So it’s surprising that the permanent-colostomy patients ended up happier six months after the operation than the temporary group, whose members were still holding out hope. Patients with a temporary colostomy experienced a significant drop in life satisfaction versus patients in the permanent group.

It might seem strange that patients who are better off objectively were less satisfied with their lives, yet the finding makes sense: “If your condition is temporary,” Ubel explains, “you’re thinking, I can’t wait until I get rid of this.” Ubel says thoughts like these keep you from moving on with your life and focusing on the many good things that remain.

Friday, January 04, 2008

Clutter - more in the brain than in the house...

Parker-Pope offers a brief essay on the "clutter problem," suggesting that the problem in many cases is not a house problem but a person problem.
Excessive clutter and disorganization are often symptoms of a bigger health problem...At its most extreme, chronic disorganization is called hoarding...David F. Tolin, director of the anxiety disorders center at the Institute of Living in Hartford and an adjunct associate professor of psychiatry at Yale...recently studied compulsive hoarders using brain-scan technology. While in the scanner, hoarders looked at various possessions and made decisions about whether to keep them or throw them away. The items were shredded in front of them, so they knew the decision was irreversible. When a hoarder was making decisions about throwing away items, the researchers saw increased activity in the orbitofrontal cortex, a part of the brain involved in decision-making and planning...people who didn’t hoard showed no extra brain activity.
The article continues with a discussion of holding on to excess 'stuff' and being overweight. In several cases therapists have noted a correlation between reducing clutter and weight loss.

Cultural Influences on Neural Substrates of Attentional Control

The abstract from Hedden et al. of the article with the title of this post (in Psychological Science, Volume 19, pp 12-17, 2008). I thought it was interesting enough to mention, though I don't have access to the full text, so can't determine exactly what is meant by culturally preferred and non-preferred judgements:
Behavioral research has shown that people from Western cultural contexts perform better on tasks emphasizing independent (absolute) dimensions than on tasks emphasizing interdependent (relative) dimensions, whereas the reverse is true for people from East Asian contexts. We assessed functional magnetic resonance imaging responses during performance of simple visuospatial tasks in which participants made absolute judgments (ignoring visual context) or relative judgments (taking visual context into account). In each group, activation in frontal and parietal brain regions known to be associated with attentional control was greater during culturally nonpreferred judgments than during culturally preferred judgments. Also, within each group, activation differences in these regions correlated strongly with scores on questionnaires measuring individual differences in culture-typical identity. Thus, the cultural background of an individual and the degree to which the individual endorses cultural values moderate activation in brain networks engaged during even simple visual and attentional tasks.