A new brain correlate of intention.

We have another installment in the story of how our conscious intention to move involves brain processes parallel to those that actually command the movements. It has been known for some time that stimulation of the presupplementary motor area in clinical exploration before brain surgery can produce an 'urge to move.' Desmurget et al. now find that stimulating areas in the inferior posterior parietal cortex (usually presumed to be involved in sensory motor coordination, not volition) can cause an urge to move specific body parts. When stimulation intensity was increased in parietal areas, participants believed they had really performed these movements, although no electromyographic activity was detected. Stimulation of the premotor region triggered overt mouth and contralateral limb movements. Yet, patients firmly denied that they had moved. Conscious intention and motor awareness thus arise from increased parietal activity before movement execution. Here is a figure from the review of this work by Haggard.

Voluntary action. (Top) The premotor cortex prepares commands for voluntary actions triggered by external stimuli, whereas the presupplementary motor area prepares commands for internally generated "intentional" actions, which are then executed by the primary motor cortex. Signals containing copies of prepared motor commands are also sent to the parietal cortex, where they are used to predict sensory consequences of movement. (Bottom) The preparation of motor commands for voluntary movement by the presupplementary motor area causes a sense of urge. The inferior part of the posterior parietal cortex generates sensory representations of the predicted consequences of the movement.

Evolutionary change driven by sufficiency, not survival

Polymath Adam Gopnik writes a nice piece in the May 11 issue of The New Yorker titled "The Fifth Blade." The title refers to the appearance (evolution) of razors with increasingly (functionally irrelevant) numbers of blades since the Wilkinson Sword company started mass-producing stainless-steel blades in 1961. This is consonant with a new suggested principle of biological evolution, quite at variance with the classical view that innovation is borne out of a struggle for survival amidst limited resources - that in dull periods of plenty, stasis was supposed to rule.

The new idea is almost the opposite. Terrence Deacon, for instance, a professor of biological anthropology and linguistics at Berkeley, has argued that animals' appearance alters and their behavior changes - birds brighten and their songs grow elaborate - not in conditions of scarcity, where bird fights bird for every seed, but in landscapes of plentitude...once "selection pressure" lifts - once it doesn't matter so much if every claw kills, if every molar crunches - then the animal can do its own thing and find its own pleasures. This pattern makes for what Deacon calls "relaxed selection, like relaxed-fit jeans.

Relaxed evolution favors the Ronald Firbanks over the Cotton Mathers, the playful dandy over the sober saver. Relaxed selection explains creativity in language and literature: once we no longer have to pressure our bodies to chew and hunt, the big heads behind them, having nothing to do, start doing what they please. It isn't the struggle for existence but the serenity of entertainment that explains our lives. The brain starts thinking as the jaw relaxes. We human beings are all three-blade razors, Gillete Mach3 Turbos and Shick Xtreme3s, with needless cutting surfaces and useless batteries, buzzing away, wasting energy and look sexy, forged in plenty and thriving in abundance.

How the brain talks to itself - errors in emotional prediction

Gilbert and Wilson offer an engaging essay in the Philisophical Transactions of the Royal Society B (PDF here) titled: "Why the brain talks to itself: sources of error in emotional prediction." In trying to plan futures that involve more pleasure than pain, we perform mental simulations (previews) of future events, which produce affective reactions (premotions), which are then used as a basis for forecasts (predictions) about the future event’s emotional consequences. Their review summarizes several main sources of systematic errors of these predictions.

Previews have several problems of dissimilar content:

1. They provide a poor basis for prediction because they tend to be based on memories that are not representative of the future events that those previews were meant to simulate.
2. They tend to omit features that are incidental to the event but that nonetheless may have a significant impact on our emotional reactions to it.
3. They tend to emphasize the early occurring moments of the event in which emotions are likely to be the most intense.
4. They include comparisons that views do not. (Imaginary chips are readily compared to imaginary sardines, but real chips are not.)

Previews also have problems of dissimilar context:

...accurate predictions also require that the context in which previewing occurs be similar to the context in which viewing occurs, and as it turns out, this is not always the case either. Why do contexts matter? Premotions are not just reactions to previews; they are reactions to previews and to the context in which those previews are generated. That is why we feel happier when we preview chocolate cake while we are lying on a comfortable couch than on a bed of nails, or when we are hungry rather than sated.

Brain activation in cocaine addicts caused by drug words

From Goldstein et al. :

When exposed to drug conditioned cues (stimuli associated with the drug), addicted individuals experience an intense desire for the drug, which is associated with increased dopamine cell firing. We hypothesized that drug-related words can trigger activation in the mesencephalon, where dopaminergic cells are located. During functional magnetic resonance imaging (fMRI), 15 individuals with cocaine use disorders and 15 demographically matched healthy control subjects pressed buttons for color of drug-related versus neutral words. Results showed that the drug words, but not neutral words, activated the mesencephalon in the cocaine users only. Further, in the cocaine users only, these increased drug-related mesencephalic responses were associated with enhanced verbal fluency specifically for drug words. Our results for the first time demonstrate fMRI response to drug words in cocaine-addicted individuals in mesencephalic regions as possibly associated with dopaminergic mechanisms and with conditioning to language (in this case drug words). The correlation between the brief verbal fluency test, which can be easily administered (crucial for clinical studies), and fMRI cue reactivity could be used as a biomarker of neurobiological changes in addiction.

Stepping backwards enhances cognitive control.

From Koch et al., some interesting work on the role of body locomotion in the recruitment of control processes.:

In the most fundamental and literal sense, approach refers to decreasing, and avoidance to increasing, the physical distance between the self and the outside world. In our view, body locomotion most purely taps into this fundamental nature of approach and avoidance. In everyday life, individuals typically approach desired stimuli by stepping forward and avoid aversive stimuli by stepping backward

...The idea that body locomotion may trigger approach and avoidance orientations has, so far, not been tested...we expected that stepping backward would increase the recruitment of cognitive control relative to stepping forward. To test this prediction, we gauged cognitive functioning by means of a Stroop task immediately after a participant stepped in one direction. The Stroop task requires naming the color in which stimulus words are printed while ignoring their semantic meaning, which is actually processed more automatically than the color. Cognitive control is required to override the tendency to respond to the semantic meaning and instead respond to the color.

...our study showed that stepping backward significantly enhanced cognitive performance compared to stepping forward or sideways. Considering the effect size, backward locomotion appears to be a very powerful trigger to mobilize cognitive resources. Thus, whenever you encounter a difficult situation, stepping backward may boost your capability to deal with it effectively.

Putting Off Growing Old

I pass on this item by Sherman Sutter from the editor's choice section of Science Magazine:

In a classic 1957 paper on the evolution of senescence, Williams argued that when extrinsic mortality (death due to predation, infectious disease, or accident) is high, natural selection favors investment in early reproduction. When it is low, the increased return from allocating resources to maintain and repair the soma should lead to longer life spans. In the absence of precise information on causes of death, researchers have used hazard models to partition mortality into age-independent (interpreted as extrinsic) and age-dependent components.

Taking this approach, Gurven and Fenelon analyze mortality data from 13 remote, small-scale societies and in historical cohorts from Sweden and England over the past 250 years. They explore two statistical models (Weibull and Gompertz-Makeham) of adult mortality patterns and consider three measures of actuarial aging (mortality rate doubling time, Ricklefs's {omega}, and slope of the mortality function between ages 60 and 70). The variation in results across these two estimation procedures and three measures complicates the interpretation of the data. Nonetheless, some patterns are robust: The subsistence groups and the early Swedish cohorts exhibit similar actuarial aging, but more recent European cohorts show progressively slower aging. In the longitudinal samples, slower aging and reduced extrinsic mortality are linked. Women have lower rates of senescence than men, a difference that has increased over time. These "modest but nontrivial" changes support Williams's claims, and the authors discuss individual-level mechanisms that could underlie them.

Experience as what we agree to attend to...

I have decided to paste in just a fragment of writing from a parallel private journal that I keep. It has some of my private jargon, apologies if it is not intelligible to you. It is a random walk...

...that wants to try to crystallize something from last Wednesday’s post on attention together with a reading (still going on) of Metzinger’s recent book “The Ego Tunnel.” Metzinger’s compelling analysis, along with others, shows our introspective selves to be fictions even if they are imaged to fit in a metacognitive hierarchy, such as a watcher (closer to a Damasio-style homeostatic pre-emotional core) that is sensed as observer of its products (being an angry/happy/kind/compassionate/whatever person.) All are actually logically equivalent (watch-ing, be-ing, angry-ing, desire-ing, compassion-ing). Even while being in principle illusory, many of these self models can be shown to correlate with distinctive pattern of brain activity, can be altered by brain lesions. The experiential and behavioral issue is which of these members of an imaginary governing board is being held within the limited attentional resources of the frontal lobes. (William James: “My experience is what I agree to attend to.”). Training regimes that settle this issue by putting in place new habits for what is held in attention (compassion meditation, piano or other athletic practice, etc.) can be transformative. Physical changes in brain areas serving these functions can be documented.

Prelinguistic infants, but not chimps, signal absent entities

Interesting work from Tomasello's group showing that nonlinguistic skills for displaced reference precede and underlie similar linguistic reference:

One of the defining features of human language is displacement, the ability to make reference to absent entities. Here we show that prelinguistic, 12-month-old infants already can use a nonverbal pointing gesture to make reference to absent entities. We also show that chimpanzees—who can point for things they want humans to give them—do not point to refer to absent entities in the same way. These results demonstrate that the ability to communicate about absent but mutually known entities depends not on language, but rather on deeper social-cognitive skills that make acts of linguistic reference possible in the first place. These nonlinguistic skills for displaced reference emerged apparently only after humans' divergence from great apes some 6 million years ago.

In carrying out the experiments the authors:

...confronted 12-month-old prelinguistic human infants and adult chimpanzees with two new situations in which they wanted something they could not see. In both situations, participants first repeatedly saw a human adult place several desired objects of the same kind on top of one platform, while also placing undesired objects of another kind on another, similar platform. Then, for the test, the desired objects were removed. In the occluded-referent condition, participants then saw the adult take another object of the desired kind and place it under its platform, out of sight. In this case, even though participants could not see the desired object, they knew it was there under the platform, and so they could potentially request it by pointing to its location. In the absent-referent condition, in contrast, after the adult removed the desired objects from the platform, she did not add any more, so that the usual location of the desired kind of objects was empty. In this case, if participants pointed to the now-empty platform, it would mean that they expected the adult would be able to infer that what they wanted was one of the missing kind of objects, that is, one of the kind both the adult and the participants knew was usually on that platform.

Judging honesty by story telling.

Benedict Carey summarizes work on detecting lying, not by body language cues, but by what people say. People telling the truth tend to add 20 to 30 percent more external detail than do those who are lying. If you’re telling the truth, this mental reinstatement of contexts triggers more and more external details. Not so if you’ve got a concocted story and you’re sticking to it. “It’s the difference between a tree in full flower in the summer and a barren stick in winter."

Antioxidants bad for you?

Check out this open access article by Ristow and et al.

Ramachandran and the plastic brain.

John Colapinto writes a New Yorker article on Vilayanur Ramachandran, whose work I have mentioned several times (actually, in six postings...enter Ramachandran in the search box in the left column to bring them up.) It is a biographical account, describing Ramachandran's professional development, and also describes an interesting syndrome known as apotemnophilia, the compulsion to have a healthy limb amputated. It appears to result from damage to the right superior parietal lobe which causes it to fail in assembling a normal body image for the body part perceived as alien, wanting amputation. Just as was the case with phantom limb pain and stroke induced paralysis, Ramachandran found that use of a simple mirror to differently present a body part could alleviate the symptoms. The article also describes work which suggests a link between autism and defects in the mirror neuron system.

Misconceptions of Memory: The Scooter Libby Effect

Some clips from a recent article from Daniel Gilbert and collaborators (Gilbert is the guy who wrote "Stumbling on Happiness" that I abstracted several years ago on this blog):

...during his 2007 trial, Vice-Presidential Chief of Staff I. Lewis "Scooter" Libby claimed that he could not remember mentioning the identity of a Central Intelligence Agency employee to other government officials or reporters. Jurors found it difficult to believe that Libby could have forgotten having had such important conversations and found him guilty of obstruction of justice, making false statements, and perjury
...Libby's conversations were indeed important, but they were less important at the time he had them than they became months later when the Justice Department launched its investigation. Although important information increases the motivation to remember (MTR), research on human memory suggests that MTR is considerably more effective when it arises before rather than after information is encoded...Do people take the timing of MTR into account when judging other people's memories?

Here is the experimental design:

Memorizers were told that they would study the material for 2 min before seeing the photographs and trying to recall the facts associated with each. They were also told that they would receive $0.10 for each recalled fact. Before they studied the material, memorizers in the MTR-at-encoding condition (n= 21) were told that they would receive a $0.50 bonus for each fact they remembered about the individual named Beryl White. Memorizers in the MTR-at-retrieval condition (n= 22) were told about this bonus immediately after they studied the material. Memorizers in the no-MTR condition (n= 21) were not told about the bonus. After studying the material, memorizers were shown the photograph of Beryl White and were asked to recall the facts about her.

Judges were shown the same material as memorizers and read a detailed description of the instructions from the MTR-at-encoding condition (n= 24), the MTR-at-retrieval condition (n= 21), or the no-MTR condition (n= 21). Judges were then asked to predict the percentage of memorizers in that condition who would remember each fact.

The results, shown in this figure, were extremely clear:

Participants who were asked to judge another individual's memory did not distinguish between information that was important when the individual encountered it and information that became important only later. Clearly, people's theories about the effects of motivation on memory are imperfect. It is interesting to note, in light of these findings, that the U.S. District Court denied Libby's motion to allow expert psychologists to testify about the foibles of memory and metamemory because, the court argued, such research would tell jurors little that they did not already know.

Brain correlates of self-transcendent emotions

Antonio and Hanna Damasio and collaborators have now observed brain activities associated with our internal loftier emotions that transcend self-interest, such as elevation and admiration. These are hard to measure because they don't correlate obviously with facial expressions or body language. Haidt and Morris, in their commentary in the same issue of PNAS, set the context for the work:

Emotion research has something in common with a drunk searching for his car keys under a street lamp. ‘‘Where did you lose them?’’ asks the cop. ‘‘In the alley,’’ says the drunk, ‘‘but the light is so much better over here.’’ For emotion research, the light shines most brightly on the face, whose movements can be coded, compared across cultures, and quantified by electromyography. All of the ‘‘basic’’ emotions described by Paul Ekman and others (happiness, sadness, anger, fear, surprise, and disgust) earned their place on the list by being face-valid. The second source of illumination has long been animal research. Emotions that can be reliably triggered in rats, such as fear and anger, have been well-studied, down to specific pathways through the amygdala. But emotions that cannot be found on the face or in a rat, such as moral elevation and admiration, are largely abandoned back in the alley. We know they are there, but nobody can seem to find a flashlight. It is therefore quite an achievement that Immordino-Yang, McCall, Damasio, and Damasio managed to drag an fMRI scanner back there and have given us a first glimpse of the neurological underpinnings of elevation and admiration.

Here is the abstract and a figure from the paper:

In an fMRI experiment, participants were exposed to narratives based on true stories designed to evoke admiration and compassion in 4 distinct categories: admiration for virtue (AV), admiration for skill (AS), compassion for social/psychological pain (CSP), and compassion for physical pain (CPP). The goal was to test hypotheses about recruitment of homeostatic, somatosensory, and consciousness-related neural systems during the processing of pain-related (compassion) and non-pain-related (admiration) social emotions along 2 dimensions: emotions about other peoples' social/psychological conditions (AV, CSP) and emotions about others' physical conditions (AS, CPP). Consistent with theoretical accounts, the experience of all 4 emotions engaged brain regions involved in interoceptive representation and homeostatic regulation, including anterior insula, anterior cingulate, hypothalamus, and mesencephalon. However, the study also revealed a previously undescribed pattern within the posteromedial cortices (the ensemble of precuneus, posterior cingulate cortex, and retrosplenial region), an intriguing territory currently known for its involvement in the default mode of brain operation and in self-related/consciousness processes: emotions pertaining to social/psychological and physical situations engaged different networks aligned, respectively, with interoceptive and exteroceptive neural systems. Finally, within the anterior insula, activity correlated with AV and CSP peaked later and was more sustained than that associated with CPP. Our findings contribute insights on the functions of the posteromedial cortices and on the recruitment of the anterior insula in social emotions concerned with physical versus psychological pain.


Figure (click to enlarge). Relative activation in the posteromedial cortices (PMC, outlined in pink) for admiration for virtue and compassion for social pain (AV/CSP, blue3 green) versus admiration for skill and compassion for physical pain (AS/CPP, orange 3 yellow). The image is thresholded at q(FDR)  0.05. The bar to the right provides a color code for t statistics associated with the contrast. The red box frames the location of the magnified view. Note the clear separation between the anterosuperior sector activated by AS/CPP, and the posteroinferior activated by AV/CSP.

As an added note: The commentary by Haidt and Morris offers an interesting table summarizing the number of articles on the main moral emotions other than compassion (on which a lot has been done), showing the number of articles in the PsycINFO database for which the emotion name was in the title or keywords fields.

The amazing aging brain - continued

This website on aging created by the Oregon Museum of Science and Industry has shifted locations quite a bit since I first mentioned it. My thanks to MindBlog reader Maryann S. Marino for tracking it down.

Gross national happiness

Seth Mydans describes how the tiny Himalayan kingdom of Bhutan (population ~700,000) is making an effort to replace GNP (gross national product) with GNH (gross national happiness) as the most meaningful indicator of a nation's health. After the World Bank and the I.M.F. essentially said OK.......but how do you measure it?, the government devised an intricate model of well-being, that in true Buddhist form, gets into huge lists and sub-lists: the four pillars, nine domains, and 72 indicators of happiness.

Gross national happiness has a broader application for Bhutan as it races to preserve its identity and culture from the encroachments of the outside world...Bhutan is pitting its four pillars, nine domains and 72 indicators against the 48 channels of Hollywood and Bollywood that have invaded since television was permitted a decade ago...Before June 1999 if you asked any young person who is your hero, the inevitable response was, ‘The king,’ Immediately after that it was David Beckham, and now it’s 50 Cent, the rap artist. Parents are helpless...So if G.N.H. may hold the secret of happiness for people suffering from the collapse of financial institutions abroad, it offers something more urgent here in this pristine culture.

The neuroeconomics of taking your pick.

Whaley offers a summary of papers by Martino et al. (open access) and Sharot et al. in a recent issue of J. Neurosci and a more recent paper by Croxson et al. notes correlates of cost-benefits valuation. Excerpts from Whaley:

To deal with the countless decisions that it makes, the brain must assign values to each available option. However, the perceived value of an option can be influenced by multiple factors. Two recent papers shed light on the brain regions involved in the neural representation of value.

Choosing between several equally appealing options is difficult; however, once a decision is made, our expectations of our chosen option's value often become inflated with respect to that of the rejected alternatives. Sharot et al. carried out functional MRI (fMRI) of participants as they estimated how much they would enjoy vacationing in various destinations before and after choosing one of two equally rated vacations. This demonstrated that the relative sizes of the blood oxygen level-dependent (BOLD) signals in the caudate nucleus in response to the initial presentation of the destinations predicted subsequent choices. As expected, after making their selection, participants rated their chosen destination higher than the rejected destination. Furthermore, the differences in the caudate nucleus BOLD signal response to selected versus rejected options increased after the selection, suggesting that the act of choosing can itself alter the neurobiological representation of an option's value.

The 'endowment effect' is our tendency to value objects that we own and are selling more highly than identical objects belonging to others that we are thinking of buying. It is thought to arise because an object's value with respect to a reference point (in this case, owning the item) is altered by the individual's position as buyer or seller in the transaction. De Martino et al. asked participants how much they would accept in payment for or spend on lottery tickets with different expected payoffs. fMRI showed that activity in the ventral striatum correlated highly with the behavioural tendency to overvalue items when selling and undervalue items when buying, suggesting that this region contributes to the reference-dependent valuation of items.

These two studies provide insights into some of the neural mechanisms involved in encoding value in the brain and how these representations may be altered by previous decisions or social context.

Are E-readers our future?

I certainly hope not, based on my experience with the Amazon Kindle ^* - compared with a normal book, hopelessly slow, hard to jump around easily. And forget trying anything but fiction and simple text. I've read some of the psychology books I've mentioned on the Kindle, and tables and references are either screwed up or simply not there. And for the fiction that I still read on an E-reader, I find the iPhone Kindle App more congenial that my original Kindle, because I'm carrying around the iPhone all the time anyway. This article by Brad Stone, on how E-readers might save newspapers, is a nice summary of some of the issues. Any large thin tablet device will have to have color graphic and videos, like our current computers (Apple is said to be working on one). I don't think I'm going to be happy even with that, because the NYTimes.com site that I frequently use to excerpt stuff for this blog isn't as much fun as the real newspaper - which allows you to jump around more rapidly and easily in the content using our primitive biological search appendages - arms and hands. (Added note: a larger version of the Kindle has just been announced, which I still think doesn't cut it.)

^*(An interesting fact arises from looking at the Kindle user base. Half of reporting Kindle owners are 50 or older, and 70 percent are 40 or older. Many report buying a Kindle because of a variety of impairments: hand arthritis, weakening eyes, etc.)

Faith in flux...

The Pew Forum has put out an interesting study with the title of this post. From a summary by Blow:

..most children raised unaffiliated with a religion later choose to join one...While science, logic and reason are on the side of the nonreligious, the cold, hard facts are just so cold and hard. Yes, the evidence for evolution is irrefutable. Yes, there is a plethora of Biblical contradictions. Yes, there is mounting evidence from neuroscientists that suggests that God may be a product of the mind. Yes, yes, yes. But when is the choir going to sing? And when is the picnic? And is my child going to get a part in the holiday play?

As the nonreligious movement picks up steam, it needs do a better job of appealing to the ethereal part of our human exceptionalism — that wondrous, precious part where logic and reason hold little purchase, where love and compassion reign. It’s the part that fears loneliness, craves companionship and needs affirmation and fellowship...Being regularly surrounded by a community that shares your convictions and reinforces them through literature, art and ritual is incredibly powerful, and yes, spiritual.

Issue of our times: concentration versus distractability

John Tierny does a great article on the science of concentration. I know this is a huge issue for me. I find that my constant scanning of tables of contents of various journals for tidbits that might go in this blog leaves my attention constantly flitting about, as I feel like an overstuffed goose that continues to peck around ingesting more random pieces than can be properly digested. While attending to a task I am easily distracted (a documented feature of aging!). Here are some clips from Tierny's article, which notes the recent book “Rapt,” a guide by Winifred Gallagher to the science of paying attention. The book's theme:

...is borrowed from the psychologist William James: “My experience is what I agree to attend to.” You can lead a miserable life by obsessing on problems. You can drive yourself crazy trying to multitask and answer every e-mail message instantly...Or you can recognize your brain’s finite capacity for processing information, accentuate the positive and achieve the satisfactions of what Ms. Gallagher calls the focused life.

The work of Desimone and collaborators at MIT is mentioned:

When something bright or novel flashes, it tends to automatically win the competition for the brain’s attention, but that involuntary bottom-up impulse can be voluntarily overridden through a top-down process that Dr. Desimone calls “biased competition.” He and colleagues have found that neurons in the prefrontal cortex — the brain’s planning center — start oscillating in unison and send signals directing the visual cortex to heed something else.

Now that neuroscientists have identified the brain’s synchronizing mechanism, they’ve started work on therapies to strengthen attention. In the current issue of Nature, researchers from M.I.T., Penn and Stanford report that they directly induced gamma waves in mice by shining pulses of laser light through tiny optical fibers onto genetically engineered neurons. In the current issue of Neuron, Dr. Desimone and colleagues report progress in using this “optogenetic” technique in monkeys.

Ultimately, Dr. Desimone said, it may be possible to improve your attention by using pulses of light to directly synchronize your neurons, a form of direct therapy that could help people with schizophrenia and attention-deficit problems (and might have fewer side effects than drugs). If it could be done with low-wavelength light that penetrates the skull, you could simply put on (or take off) a tiny wirelessly controlled device that would be a bit like a hearing aid.

Further comments from Gallagher, who:

...advocates meditation to increase your focus, but...there are also simpler ways to put the lessons of attention researchers to use. Once she learned how hard it was for the brain to avoid paying attention to sounds, particularly other people’s voices, she began carrying ear plugs with her. When you’re trapped in a noisy subway car or a taxi with a TV that won’t turn off, she says you have to build your own “stimulus shelter.”...She recommends starting your work day concentrating on your most important task for 90 minutes. At that point your prefrontal cortex probably needs a rest, and you can answer e-mail, return phone calls and sip caffeine (which does help attention) before focusing again. But until that first break, don’t get distracted by anything else, because it can take the brain 20 minutes to do the equivalent of rebooting after an interruption. (For more advice, go to nytimes.com/tierneylab.)

“Multitasking is a myth,” Ms. Gallagher said. “You cannot do two things at once. The mechanism of attention is selection: it’s either this or it’s that.” She points to calculations that the typical person’s brain can process 173 billion bits of information over the course of a lifetime....“People don’t understand that attention is a finite resource, like money,” she said. “Do you want to invest your cognitive cash on endless Twittering or Net surfing or couch potatoing? You’re constantly making choices, and your choices determine your experience, just as William James said.”

Civilization has caused the decline of human health

I've just finished reading Michael Pollan's "In Defense of Food: An Eater's Manifesto," which is a scary documentation of how modern food technology and 'nutritionism' have significantly increased obesity, diabetes and coronary disease in this century, particularly since the second world war. Thus Ann Gibbons' summary (from presentations at the recent Americal Assoc. of Physical Anthropologists' meeting) of the effects of our earlier transition from hunting/gathering to agriculture makes a lot of sense. A major project has pooled work from 72 researchers to provide the first analysis of data on 11,000 individuals who lived from 3000 years ago until 200 years ago throughout Europe and the Mediterranean. The analysis involves standardized indicators of health from skeletal remains, including stature, dental health, degenerative joint disease, anemia, trauma, and the isotopic signatures of what they ate.

...the health of many Europeans began to worsen markedly about 3000 years ago, after agriculture became widely adopted in Europe and during the rise of the Greek and Roman civilizations. They document shrinking stature and growing numbers of skeletal lesions from leprosy and tuberculosis, caused by living close to livestock and other humans in settlements where waste accumulated. The numbers of dental hypoplasias and cavities also increased as people switched to a grain-based diet with fewer nutrients and more sugars...After a long, slow decline through the Middle Ages, health began to improve in the mid-19th century. Stature increased, probably because of several factors: The little Ice Age ended and food production rose, and better trade networks, sanitation, and medicine developed... But take heed: Overall health and stature in the United States has been declining slightly since the 1950s, possibly because obese Americans eat a poor-quality diet, not unlike early farmers whose diet was less diverse and nutritious than that of hunter-gatherers.