Thursday, March 15, 2007

And, speaking of musicians...

Haydn Fantasia in C Major:

The brains of musicians are different...

When asked to mark the center of a horizontal line, neurologically intact right-handers show a slight yet reliable tendency to bisect about 2% to the left of the true center. Patston et al show that that musicians show a slight rightward bias, suggesting left pseudoneglect, and also that musicians bisect the lines more accurately than nonmusicians.


Figure: Mean percentage deviation from the true center in the line-bisection task according to group (musicians vs. nonmusicians) and hand used. Negative numbers denote leftward bias, and positive numbers denote rightward bias. Error bars represent mean standard error.

Currently, there is considerable interest in the musical brain as a window into neurodevelopmental plasticity, with reports of both white-matter and gray-matter differences between musicians and nonmusicians. This work suggests that musicians may develop an increased ability for the left hemisphere to perform cognitive functions that are usually right-hemisphere dominant, and is consistent with the idea that musical training can have perceptual and cognitive effects beyond the auditory modality.

Brain response to threat - reduced by holding hands

Coan, Schaeffer, and Davidson show how social support reduces brain arousal in response to threat. Their abstract:
Social contact promotes enhanced health and well-being, likely as a function of the social regulation of emotional responding in the face of various life stressors. For this functional magnetic resonance imaging (fMRI) study, 16 married women were subjected to the threat of electric shock while holding their husband's hand, the hand of an anonymous male experimenter, or no hand at all. Results indicated a pervasive attenuation of activation in the neural systems supporting emotional and behavioral threat responses when the women held their husband's hand. A more limited attenuation of activation in these systems occurred when they held the hand of a stranger. Most strikingly, the effects of spousal hand-holding on neural threat responses varied as a function of marital quality, with higher marital quality predicting less threat-related neural activation in the right anterior insula, superior frontal gyrus, and hypothalamus during spousal, but not stranger, hand-holding.
A figure from the paper (click on figure to enlarge it):

Legend - Threat-responsive regions of interest affected by hand-holding condition. Green clusters highlighting right dorsolateral prefrontal cortex (rDLPFC), left caudate–nucleus accumbens (lCd/Na), and superior colliculus (SC) indicate spouse-related attenuation. Blue clusters highlighting the ventral anterior cingulate cortex (vACC), posterior cingulate (PC), right postcentral gyrus (rPG), and left supramarginal gyrus (lSMG) indicate attenuation associated with both spouse and stranger hand-holding.

Wednesday, March 14, 2007

Conscious Reasoning and Intuition in Moral Judgment

Cushman, Young, and Hauser. at Harvard, ask...
Is moral judgment accomplished by intuition or conscious reasoning?
They
...investigated three principles that guide moral judgments: (a) Harm caused by action is worse than harm caused by omission, (b) harm intended as the means to a goal is worse than harm foreseen as the side effect of a goal, and (c) harm involving physical contact with the victim is worse than harm involving no physical contact.
They note that
A critical ingredient missing from the current debate is an experimental method that clearly links data on moral judgment with data on moral justification. Without establishing that an individual uses a specific moral principle, it makes little sense to ask whether the content of that principle is directly available to conscious reasoning. Therefore, in the present study, we first identified three moral principles used by subjects in the judgment of moral dilemmas, and then explored the extent to which subjects generated justifications based on these principles....Asking whether these principles are invoked to explain moral judgments, we found that subjects generally appealed to the first and third principles in their justifications, but not to the second.
These experiments support the view:
that moral judgment can be accomplished by multiple systems: Some moral principles are available to conscious reflection—permitting but not guaranteeing a role for conscious reasoning—whereas others are better characterized by an intuitionist model.
Take Marc Hauser's Moral Sense Test

NeuroLaw

The March 11 Sunday Times Magazine has an excellent article on the impact of neuroscience research on assigning guilt or innocence in criminal cases. I am posting only a few clips from the article and recommend that you read the entire piece, which you can download here.

THE RISE OF NEUROLAW....
Some sort of organic brain defense has become de rigueur in any sort of capital defense...Lawyers routinely order scans of convicted defendants’ brains and argue that a neurological impairment prevented them from controlling themselves. The prosecution counters that the evidence shouldn’t be admitted, but under the relaxed standards for mitigating evidence during capital sentencing, it usually is. Indeed, a Florida court has held that the failure to admit neuroscience evidence during capital sentencing is grounds for a reversal.
THE END OF RESPONSIBILITY?
In a landmark case the landmark case a divided Supreme Court struck down the death penalty for offenders who committed crimes when they were under the age of 18.

The leading neurolaw brief in the case, filed by the American Medical Association and other groups, argued that because “adolescent brains are not fully developed” in the prefrontal regions, adolescents are less able than adults to control their impulses and should not be held fully accountable “for the immaturity of their neural anatomy.” In his majority decision, Justice Anthony Kennedy declared that “as any parent knows and as the scientific and sociological studies” cited in the briefs “tend to confirm, ‘[a] lack of maturity and an underdeveloped sense of responsibility are found in youth more often than in adults.’ ” Although Kennedy did not cite the neuroscience evidence specifically, his indirect reference to the scientific studies in the briefs led some supporters and critics to view the decision as the Brown v. Board of Education of neurolaw.
PUTTING THE UNCONSCIOUS ON TRIAL...
Two companies, No Lie MRI and Cephos, are now competing to refine f.M.R.I. lie-detection technology so that it can be admitted in court and commercially marketed.
ARE YOU RESPONSIBLE FOR WHAT YOU MIGHT DO?....

Neuroscience, it seems, points two ways: it can absolve individuals of responsibility for acts they’ve committed, but it can also place individuals in jeopardy for acts they haven’t committed — but might someday.
WHAT IS AHEAD?
As the new technologies proliferate, even the neurolaw experts themselves have only begun to think about the questions that lie ahead. Can the police get a search warrant for someone’s brain? Should the Fourth Amendment protect our minds in the same way that it protects our houses? Can courts order tests of suspects’ memories to determine whether they are gang members or police informers, or would this violate the Fifth Amendment’s ban on compulsory self-incrimination? Would punishing people for their thoughts rather than for their actions violate the Eighth Amendment’s ban on cruel and unusual punishment? However astonishing our machines may become, they cannot tell us how to answer these perplexing questions. We must instead look to our own powers of reasoning and intuition, relatively primitive as they may be....neuroscience itself can never identify the mysterious point at which people should be excused from responsibility for their actions because they are not able, in some sense, to control themselves. That question, he suggests, is “moral and ultimately legal,” and it must be answered not in laboratories but in courtrooms and legislatures. In other words, we must answer it ourselves.

Tuesday, March 13, 2007

Making Us/Them Dichotomies More Benign.

Interesting thoughts from Robert Sapolsky:
A truly discouraging thing to me is how easily humans see the world as dichotomized between Us and Them. This comes through in all sorts of ways —social anthropology, lord of the flies, prison experiments, linguistics (all those cultures where the word for the members of that culture translates into "People," thus making a contrast with the non-people living in the next valley). As a neurobiologist, I'm particularly impressed with and discouraged by one finding relevant to this. There's a part of the brain called the amygdala that has lots to do with fear and anxiety and aggression. Functional brain imaging studies of humans show that the amygdala becomes metabolically active when we look at a scary face (even when the face is flashed up so quickly that we aren't consciously aware of seeing it). And some recent work—solid, done by top people, independently replicated — suggests that the amygdala can become activated when we view the face of someone from another race. The Them as scary, and the Them being someone whose skin color is real different from our own. Damn, that's an upsetting finding. But right on the heels of those studies are follow-ups showing that the picture is more complicated. The "Other skin color = scared activated amygdala = the Other" can be modified by experience. "Experience," can be how diverse of a world you grew up in. More diversity, and the amygdala is likely to become activated in that circumstance. And also, "experience," can be whether, shortly before your amygdala is put through the brain imaging paces, you are subtly biased to think about people categorically or as individuals. If you're cued towards individuating, your amygdala doesn't light up. Thus, it seems quite plausible to me that we are hard-wired towards making Us/Them distinctions and not being all that nice to the Them. But what is anything but hard-wired is who counts as an Us and as a Them —we are so easily manipulated into changing those categories. So, I'm optimistic that with the right sort of priorities and human engineering (whatever that phrase means), we can be biased towards making Us/Them dichotomies far more benign than they tend to be now. Say, by making all of us collectively feel like an Us with Them being the space aliens that may attack us some day. Or making the Them to be mean, shitty, intolerant people without compassion. But, I'm sure not optimistic that we'll soon be having political, religious or cultural leaders likely to move us effectively in that direction. Just to deflate that optimism.

Brain cells and arrangements unique to human cerebral cortex

A New Focus article in the March 2 issue of Science by Michael Balter reviews work on several brain neuronal types and arrangements that are distinctive to humans and great apes.

Spindle neurons (also called Von Economo or VEN neurons after their Austrain discoverer) are provide one example (credit J. Allman):

...these neurons are located in only two parts of the brain: the anterior cingulate cortex, deep in the center of the brain, and the frontoinsular cortex, located inside the frontal lobes. In humans, both of these structures appear to be involved in aspects of social cognition such as trust, empathy, and feelings of guilt and embarrassment. Not only were VENs unique to great apes, but humans had many more VENs than other apes. And the human VENs were markedly larger.
John Allman of Cal Tech suggests that
...the large VENs might relay information rapidly from the anterior cingulate and frontoinsular cortices to other parts of the brain....They are really stripped-down, high-performance kinds of cells...the big VENs might help humans adjust behavior swiftly in response to rapidly changing social situations....
New data on dementia seem to fit that notion.
Last December, a team led by William Seeley at UC San Francisco reported in Annals of Neurology that subjects afflicted with a type of dementia that causes inappropriate and impulsive social behavior had 74% fewer VENs in their anterior cingulate cortex compared to normal controls.
The article goes on to discuss the fact that minicolumns of the, groups of 80 to 100 nerve cells bundled together vertically in the cerebral cortex are much wider in humans than in chimps and monkeys (average of 51 versus 36 micrometers) due to an increase in the space taken up by neuropil (the axons, dendrites, and synapses that make neural connections). That is, there are many more connections.

Astrocyte Cells: (Credit: Oberheim et al. Univ. Rochester)

It also turns out that that levels of the messenger RNA that makes thrombospondins - large proteins released by astrocytes which trigger synapse formation - are six times higher in human cerebral cortex than in chimps or monkeys. The differences were seen in the cerebral cortex but not in the cerebellum and nonbrain tissues. (Astrocytes are support cells that make up nearly half the cells in the human brain, but their functions have remained a mystery.)

Monday, March 12, 2007

Alter a gene - make more fearless mice

Here is a brief clip on material I have mentioned previously...

Odor cues during sleep stimulate memory.

The March 9 issue of Science has an interesting report by Rasch et al. and commentary by Miller on experiments demonstrating that pulses of an odor (rose scent) given during a learning task, improve consolidation of the memory of that task if given also during slow-wave sleep. The abstract:
Sleep facilitates memory consolidation. A widely held model assumes that this is because newly encoded memories undergo covert reactivation during sleep. We cued new memories in humans during sleep by presenting an odor that had been presented as context during prior learning, and so showed that reactivation indeed causes memory consolidation during sleep. Re-exposure to the odor during slow-wave sleep (SWS) improved the retention of hippocampus-dependent declarative memories but not of hippocampus-independent procedural memories. Odor re-exposure was ineffective during rapid eye movement sleep or wakefulness or when the odor had been omitted during prior learning. Concurring with these findings, functional magnetic resonance imaging revealed significant hippocampal activation in response to odor re-exposure during SWS.

Robot Dreams

There is a very interesting exchange in the Letter section of the March 2 issue of Science Magazine. R. Conduit comments on a perspectives article "What do robots dream of?" (17 Nov. 2006, p. 1093) by C. Adami, which provides an interesting interpretation of the Report "Resilient machines through continuous self-modeling" by J. Bongard et al. (17 Nov. 2006, p. 1118).

Bongard et al. designed a robot with an algorithm of its stored sensory data to indirectly infer its physical structure. The robot was able to generate forward motion more adaptively by manipulating its gait to compensate for simulated injuries. Adami equates this algorithm to "dreams" of prior actions and asks whether such modeling could extend to environmental mapping algorithms. If this were possible, then a robot could explore a landscape until it is challenged by an obstacle; overnight, it could replay its actions against its model of the environment and generate (or synthesize) new actions to overcome the obstacle (i.e., "dream up" alternative strategies). It could then return the next day with a new approach to the obstacle......

This work in robotics complements current findings regarding sleep and dreaming in humans. There is now strong evidence in human sleep research showing that performance on motor and visual tasks is strongly dependent on sleep, with improvements consistently greater when sleep occurs between test and retest. This is generally believed to be related to neural recoding processes that are possibly connected to dreaming during sleep). However, when one considers human dreaming, it is not a simple replay of daily scenarios. It has complex, distorted images from a vast variety of times and places in our memory, arranged in a random, bizarre fashion. If we are to model such activity in robots, we would need to have some form of "sleep" algorithm that randomizes memory and combines it in unique arrays. This could be a way to generate unique approaches to scenarios that could be simulated. Otherwise, how else would scenario replay be an improvement over repeated trials in the environment?when one considers human dreaming, it is not a simple replay of daily scenarios. It has complex, distorted images from a vast variety of times and places in our memory, arranged in a random, bizarre fashion. If we are to model such activity in robots, we would need to have some form of "sleep" algorithm that randomizes memory and combines it in unique arrays. This could be a way to generate unique approaches to scenarios that could be simulated. Otherwise, how else would scenario replay be an improvement over repeated trials in the environment?


After a further comment letter from C. Adami, Lipson, Zykov and Bongard (the original authors) comment:

The analogy between machine and human cognition may suggest that reported bizarre, random dreams may not be entirely random. The robot we described did not just replay its experiences to build consistent internal self-models and then "dream up" an action based on those models. Instead, it synthesized new brief actions that deliberately caused its competing internal models to disagree in their predictions, thus challenging them to falsify less plausible theories and, as a result, improving its overall knowledge of self. It is possible that the mangled experiences that people report as bizarre dreams correspond to this unconscious search for actions able to clarify their self-perceptions. Many of the intermediate candidate models and actions developed by the robot (as seen in Movie S1 in our Supporting Online Material) were indeed very contorted, but were optimized nonetheless to elucidate uncertainties. Edelman (1), Calvin (2), and others have suggested the existence of competitive processes in the brain. Perhaps the fact that human dreams appear mangled and brief is exactly because they are--as in the robot--"optimized" to challenge and improve these competing internal models?

Indeed, analogies between machines learning from past experiences and human dreaming are potentially very fruitful and may be applicable in both directions. Although robots and their onboard algorithms are clearly simpler and may bear little or no direct relation to humans and their minds, it may be much easier to test hypotheses about humans in robots. Conversely, ideas from human cognition research may help direct robotic research beyond merely serving as inspiration. Specifically, it is likely that as robots become more complex and their internal models are formed indirectly rather than being explicitly engineered and represented, indirect probing techniques developed for studying humans may become essential for analyzing machines too.

Friday, March 09, 2007

Ultimately, monopolies fail...

An essay by Barry Smith argues that attempts to dictate our tastes, our preference, our culture, our media, our political policies, or moral choices are bound in the end to fail because of the basic nature of our human cognition.
...Restless creatures that we are, we seek out variety and difference, opportunities to extend the scope of our thinking and to exercise discrimination and taste. This may make us hard to satisfy, but, ultimately, it is this lack of satisfaction that leads to progress and spells the end of hegemonies in ideology, religion, or science...I am optimistic that people who are fed a constant diet of the same ideas, the same foods, the same TV programmes, the same religious or political dogmas will eventually come to consider other possibilities...The lesson is already being learned in the corporate world where monopolies try to cope with this by diversifying their range of services. Their chance of survival will depend on how cynically or sincerely they respond to this restless aspect of the human mind.

Human cognition depends on change and movement in order to function. Evolution has built us this way. Try staring at a blank wall for several seconds without blinking and you will find the image eventually bleaching until you can see nothing. The eye’s visual workings respond to movement and change. So too do the other parts of our cognitive systems. Feed them the same inputs successively and they cease to produce very much worth having as output. Like the shark in water, we need to keep moving or, cognitively, we die.

...there is a paradox in our nature and our restless search for change. For unless we countenance change for change’s sake, or the relativist doctrine that anything goes (—and I don’t) how do we preserve the very best of our thinking, select better quality experiences, and maintain our purposes, directions and values? How do we avoid losing sight of older wisdom while rushing towards something new? It is here, perhaps, that our need for variation and discrimination serves us best. For the quick and gimmicky, the superficially appealing but weakest objects of our thinking or targets of desire will also be the least substantial and have an essential blandness that can tire us quickly. Besides, the more experience we have, the larger the background against which to compare and judge the worth or quality of what is newly encountered, and to decide if it will be ultimately rewarding. Certainly, people can be fickle or stubborn, but they are seldom fickle or stubborn for long. They will seek out better, according to what they are presently capable of responding to, and they will be dissatisfied by something not worthy of the attention they are capable of. For this reason attempts to dictate their tastes, cultural goods, ideologies or ideas are bound in the end to fail, and about that, and despite of many dark forces around us, I am optimistic.

Losing a night's sleep makes you less able to form new memories.

Yoo et al. report that :
..a single night of sleep deprivation produces a significant deficit in hippocampal activity during episodic memory encoding, resulting in worse subsequent retention. Furthermore, these hippocampal impairments instantiate a different pattern of functional connectivity in basic alertness networks of the brainstem and thalamus. We also find that unique prefrontal regions predict the success of encoding for sleep-deprived individuals relative to those who have slept normally. These results demonstrate that an absence of prior sleep substantially compromises the neural and behavioral capacity for committing new experiences to memory. It therefore appears that sleep before learning is critical in preparing the human brain for next-day memory formation—a worrying finding considering society's increasing erosion of sleep time.

Thursday, March 08, 2007

Sad News....


A friend has emailed me that his beloved iMac was laid to rest today in Chicago Heights..it was an open-pallet service.

Why stronger sniffing catches weak odors...

Grosmaitre et al. report in Nature Neuroscience that up to half of mammalian olfactory sensory neurons respond to mechanical stimulation through air-pressure changes, as well as to specific smells. The responses seem to share the same cellular pathway, with increased air pressure raising the firing rate of neurons that have been weakly stimulated by odorants. This mechanism may help to synchronize the firing of neurons in the olfactory bulb with breathing.

Why do we believe - Darwin’s God

Credit: New York Times

The New York Times Sunday Magazine of 3/4/07 contains an interesting article by Robin Marantz Henig on why:
...there seems an inherent human drive to believe in something transcendent, unfathomable and otherworldly, something beyond the reach or understanding of science...The debate over why belief evolved is between byproduct theorists and adaptationists.
Byproduct Theorists:
Darwinians who study physical evolution distinguish between traits that are themselves adaptive, like having blood cells that can transport oxygen, and traits that are byproducts of adaptations, like the redness of blood. There is no survival advantage to blood’s being red instead of turquoise; it is just a byproduct of the trait that is adaptive, having blood that contains hemoglobin.

Something similar explains aspects of brain evolution, too, say the byproduct theorists...Hardships of early human life favored the evolution of certain cognitive tools, among them the ability to infer the presence of organisms that might do harm, to come up with causal narratives for natural events and to recognize that other people have minds of their own with their own beliefs, desires and intentions. Psychologists call these tools, respectively, agent detection, causal reasoning and theory of mind (or folk psychology). [See Atran, “In Gods We Trust: The Evolutionary Landscape of Religion,” 2002.]

Folkpsychology, as Atran and his colleagues see it, is essential to getting along in the contemporary world, just as it has been since prehistoric times. It allows us to anticipate the actions of others and to lead others to believe what we want them to believe; it is at the heart of everything from marriage to office politics to poker...The process begins with positing the existence of minds, our own and others’, that we cannot see or feel. This leaves us open, almost instinctively, to belief in the separation of the body (the visible) and the mind (the invisible). If you can posit minds in other people that you cannot verify empirically, suggests Paul Bloom, a psychologist and the author of “Descartes’ Baby,” published in 2004, it is a short step to positing minds that do not have to be anchored to a body. And from there, he said, it is another short step to positing an immaterial soul and a transcendent God.

The bottom line, according to byproduct theorists, is that children are born with a tendency to believe in omniscience, invisible minds, immaterial souls — and then they grow up in cultures that fill their minds, hard-wired for belief, with specifics. It is a little like language acquisition, Paul Bloom says, with the essential difference that language is a biological adaptation and religion, in his view, is not. We are born with an innate facility for language but the specific language we learn depends on the environment in which we are raised. In much the same way, he says, we are born with an innate tendency for belief, but the specifics of what we grow up believing — whether there is one God or many, whether the soul goes to heaven or occupies another animal after death — are culturally shaped...
The Adaptationists:
Trying to explain the adaptiveness of religion means looking for how it might have helped early humans survive and reproduce. As some adaptationists see it, this could have worked on two levels, individual and group. Religion made people feel better, less tormented by thoughts about death, more focused on the future, more willing to take care of themselves. As William James put it, religion filled people with “a new zest which adds itself like a gift to life . . . an assurance of safety and a temper of peace and, in relation to others, a preponderance of loving affections.”

Such sentiments, some adaptationists say, made the faithful better at finding and storing food, for instance, and helped them attract better mates because of their reputations for morality, obedience and sober living. The advantage might have worked at the group level too, with religious groups outlasting others because they were more cohesive, more likely to contain individuals willing to make sacrifices for the group and more adept at sharing resources and preparing for warfare.

One of the most vocal adaptationists is David Sloan Wilson, an occasional thorn in the side of both Scott Atran and Richard Dawkins. Wilson, an evolutionary biologist at the State University of New York at Binghamton, focuses much of his argument at the group level. “Organisms are a product of natural selection,” he wrote in “Darwin’s Cathedral: Evolution, Religion, and the Nature of Society,” which came out in 2002...Through countless generations of variation and selection, [organisms] acquire properties that enable them to survive and reproduce in their environments. My purpose is to see if human groups in general, and religious groups in particular, qualify as organismic in this sense.”

Dawkins once called Wilson’s defense of group selection “sheer, wanton, head-in-bag perversity.” Atran, too, has been dismissive of this approach, calling it “mind blind” for essentially ignoring the role of the brain’s mental machinery. The adaptationists “cannot in principle distinguish Marxism from monotheism, ideology from religious belief,” Atran wrote. “They cannot explain why people can be more steadfast in their commitment to admittedly counterfactual and counterintuitive beliefs — that Mary is both a mother and a virgin, and God is sentient but bodiless — than to the most politically, economically or scientifically persuasive account of the way things are or should be.”


So,
What can be made of atheists, then? If the evolutionary view of religion is true, they have to work hard at being atheists, to resist slipping into intrinsic habits of mind that make it easier to believe than not to believe. Atran says he faces an emotional and intellectual struggle to live without God in a nonatheist world, and he suspects that is where his little superstitions come from, his passing thought about crossing his fingers during turbulence or knocking on wood just in case. It is like an atavistic theism erupting when his guard is down. The comforts and consolations of belief are alluring even to him, he says, and probably will become more so as he gets closer to the end of his life. He fights it because he is a scientist and holds the values of rationalism higher than the values of spiritualism.

This internal push and pull between the spiritual and the rational reflects what used to be called the “God of the gaps” view of religion. The presumption was that as science was able to answer more questions about the natural world, God would be invoked to answer fewer, and religion would eventually recede. Research about the evolution of religion suggests otherwise. No matter how much science can explain, it seems, the real gap that God fills is an emptiness that our big-brained mental architecture interprets as a yearning for the supernatural. The drive to satisfy that yearning, according to both adaptationists and byproduct theorists, might be an inevitable and eternal part of what Atran calls the tragedy of human cognition.







Wednesday, March 07, 2007

A membrane protein controlling social memory and maternal care in mice.

Oxytocin is gaining increasing recognition as a master regulator of affiliative behaviors in mice as well as humans. Duo Jin et al. now show that genetically knocking out CD38, a transmembrane glycoprotein required for oxytocin secretion by axon terminals in the hypothalamus, causes defective maternal nurturing and social behavior in male and female mice. Replacement of oxytocin by subcutaneous injection or lentiviral-vector-mediated delivery of human CD38 in the hypothalamus rescues social memory and maternal care.

Yet another molecule the genetic engineers might one day dink with to make us more kind and gentle people??

Getting past "mind bugs"

From Mahzarin Banaji, Psychology Department at Harvard:
I am bullish about the mind's ability to unravel the beliefs contained within it—including beliefs about its own nature...the ability of humans everywhere to go against the grain of their own beliefs that are familiar, that feel natural and right, and that appear to be fundamentally true...

We've done this sort of unraveling many times before, whether it is about the relationship of the sun to the earth, or the relationship of other species to us. We've put aside what seemed natural, what felt right, and what came easily in favor of the opposite. I am optimistic that we are now ready to do the same with questions about the nature of our own minds. From the work of pioneers such as Herb Simon, Amos Tversky, and Danny Kahneman we know that the beliefs about our own minds that come naturally, feel right, and are easy to accept aren't necessarily true. That the bounds on rationality keep us from making decisions that are in our own interest, in the interest of those we love, in the long-term interest of our societies, even the planet, even perhaps the universe, with which we will surely have greater opportunity to interact in this century.

Here are some examples of what seems natural, feels right, and is easy to believe in—even though it isn't rational or true.

We irrationally anchor: ask people to generate their social security number and then the number of doctors in their city and the correlation between the two numbers will be significantly positive, when in fact it ought to be zero—there's no relation between the two variables. That's because we can't put the first one aside as we generate the second.

We irrationally endow: give somebody a cheap mug, and once it's "my mug" through ownership (and nothing else) it becomes, in our minds, a somewhat less cheap mug. Endowed with higher value, we are likely to demand a higher price for it than it is worth or is in our interest to demand.

We irrationally see patterns where non exist: Try to persuade a basketball player, fan, or statistician that there isn't anything to the idea of streak shooting; that chance is lumpy and that that's all there is to Michael Jordan's "hot hand".

...such "mind bugs" extend to the beliefs and preferences we have about ourselves, members of our own social groups, and those who sit farther away on a scale of social distance....We don't intend to discriminate or treat unfairly, but we do....The ability to think about one's own long range interest, to self-regulate and delay gratification, to consider the well-being of the collective, especially to view the collective as unbounded by religion, language, or nationality requires a mental leap that isn't natural or easy. And yet each new generation seems to be able to do it more successfully than the previous one...old beliefs come unraveled because such unraveling is in our self-interest...we unravel existing beliefs and preferences because we wish them to be in line with our intentions and aspirations and recognize that they are not. I see evidence of this everywhere—small acts to be the person one wishes to be rather than the person one is—and it is the constant attempt at this alignment that gives me optimism.

Some bird friends

From my condo porch:

Tuesday, March 06, 2007

Why are primate brains smarter than rodent brains of the same size?

Herculano-Houzel et al. ask whether a difference the cellular composition of rodent and primate brains might underlie the better cognitive abilities of primates. They show that that in primates:
...brain size increases approximately isometrically as a function of cell numbers, such that an 11x larger brain is built with 10x more neurons and {approx}12x more nonneuronal cells of relatively constant average size. This isometric function is in contrast to rodent brains, which increase faster in size than in numbers of neurons. As a consequence of the linear cellular scaling rules, primate brains have a larger number of neurons than rodent brains of similar size, presumably endowing them with greater computational power and cognitive abilities.

If the same rules relating numbers of neurons to brain size in rodents also applied to primates, a brain comparable to ours, with {approx}100 billion neurons, would weigh >45 kg and belong to a body of 109 tons, about the mass of the heaviest living mammal, the blue whale. This simple calculation indicates quite dramatically that cellular scaling rules differ between rodents and primates, not surprising given the different cognitive abilities of rodents and primates of similar brain size (e.g., between agoutis and owl monkeys or between capybaras and macaque monkeys).

Understanding the brain - an inductive leap?

This clip from a brief essay by Steve Grand, A.I. researcher:
"...it seems to me that almost everything we think we understand about the brain is wrong. We know an enormous amount about it now and just about none of it makes the slightest bit of sense. That's a good sign, I think. It shows us we've been looking at the wrong page of the map.

Let me try to illustrate this with a thought experiment: Suppose I give you a very complex system to study – not a brain but something equally perplexing. You discover quite quickly that one part of the system is composed of an array of elements, of three types. These elements emit signals that vary rapidly in intensity, so you name these the alpha, beta and gamma elements, and set out eagerly to study them. Placing a sensor onto examples of each type you find that their actual signal patterns are distressingly random and unpredictable, but with effort you discover that there are statistical regularities in their behaviour: beta and gamma elements are slightly more active than alpha elements; when betas are active, gammas in the same region tend to be suppressed; if one element changes in activity, its neighbours tend to change soon after; gammas at the top of the array are more active than those at the bottom, and so on. Eventually you amass an awful lot of information about these elements, but still none of it makes sense. You're baffled.

So allow me to reveal that the system you've been studying is a television set, and the alpha, beta and gamma elements are the red, green and blue phosphor dots on the screen. Does the evidence start to fit together now? Skies are blue and tend to be at the top, while fields are green and tend to be at the bottom; objects tend to move coherently across the picture. If you know what the entire TV image represents at any one moment, you'll be able to make valid predictions about which elements are likely to light up next. By looking at the entire array of dots at once, in the context of a good system-level theory of what's actually happening, all those seemingly random signals suddenly make sense. "Aha!"

The single-electrode recordings of the equivalent elements in the brain have largely been replaced by system-wide recordings made by fMRI now, but at the moment we still don't know what any of it means because we have the wrong model in our heads. We need an "aha" moment akin to learning that the phosphor dots above belong to a TV set, upon which images of natural scenes are being projected. Once we know what the fundamental operating principles are, everything will start to make sense very quickly. Painstaking deduction won't reveal this to us; I think it will be the result of a lucky hunch. But the circumstances are in place for that inductive leap to happen soon, and I find that tremendously exciting."