Childhood poverty changes adult brain emotion regulation pathways.

Kim et al. add sobering detail to the story of how the chronic stress experienced by children in poverty correlates with long term change in the emotion regulation pathways of those children when they become adults. Controlling our emotions depends on the ability of portions of our prefrontal cortex to suppress activation of our amygdala's reactivity. Apparently chronic stress in childhood blocks normal development of this inhibition. Here is the authors' statement of the significance of their work:

Childhood poverty has been linked to emotion dysregulation, which is further associated with negative physical and psychological health in adulthood. The current study provides evidence of prospective associations between childhood poverty and adult neural activity during effortful attempts to regulate negative emotion. Adults with lower family income at age 9 exhibited reduced ventrolateral and dorsolateral prefrontal cortex activity and failure to suppress amygdala activation at age 24. Chronic stressor exposure across childhood mediated the relations between family income at age 9 and prefrontal cortex activity. The concurrent adult income, on the other hand, was not associated with neural activity. The information on the developmental timing of poverty effects and neural mechanisms may inform early interventions aimed at reducing health disparities.

Do you use your head or follow your heart?

Fetterman and Robsinon do a piece of work that tries to provide evidence of what we all commonly suppose: that where we physically locate our self (head or heart) predicts aspects of personality such as rationality versus emotionality, interpersonal warmth versus distance, etc. The kind of work derives from the Lakoff and Johnson studies on embodied cognition - how conceptual metaphors guide thought, emotion, and behavior. The experimental subjects were the usual cohort (112 total, 47 female) of college undergraduates seeking psychology laboratory credit, who were asked "Irrespective of what you know about biology, which body part do you more closely associate with your self? (choose one)." A bit more detail is given, but this is apparently how heart and head types were chosen. I'm going to spare you the details of the numbered experiments that are mentioned, and just note the abstract:

The head is thought to be rational and cold, whereas the heart is thought to be emotional and warm. In 8 studies (total N = 725), we pursued the idea that such body metaphors are widely consequential. Study 1 introduced a novel individual difference variable, one asking people to locate the self in the head or the heart. Irrespective of sex differences, head-locators characterized themselves as rational, logical, and interpersonally cold, whereas heart-locators characterized themselves as emotional, feminine, and interpersonally warm (Studies 1–3). Study 4 showed that head-locators were more accurate in answering general knowledge questions and had higher grade point averages, and Study 5 showed that heart-locators were more likely to favor emotional over rational considerations in moral decision making. Study 6 linked self-locations to reactivity phenomena in daily life—for example, heart-locators experienced greater negative emotion on high stressor days. In Study 7, we manipulated attention to the head versus the heart and found that head-pointing facilitated intellectual performance, whereas heart-pointing led to emotional decision making. Study 8 replicated Study 3’s findings with a nearly year-long delay between the self-location and outcome measures. The findings converge on the importance of head–heart metaphors for understanding individual differences in cognition, emotion, and performance.

Homage to idleness.

All of a sudden this past Saturday morning there was a subtle "poof" from somewhere in my now-cyborg body and it just started thinking and writing again, most likely because its preoccupation with pain was decreasing.

I found myself savoring the period of idleness mandated by having both medial knee joints replaced, and so felt a resonance with this opinion piece by Jessica Kerwin Jenkins "Homage to the Idols of Idleness."

Our struggle against the clock is ancient. As far back as the 2nd century B.C., the Roman playwright Plautus lamented, “The gods confound the man who first found out how to distinguish the hours!” as he railed against the city’s central sundial, which served to “cut and hack my days so wretchedly.” Thousands of years later, what would Plautus make of this ringing, dinging world full of productivity apps that hack ever deeper into our days and nights?

Devices that constantly keep us on course, fixed in place and in time — from the GPS to Siri — ruin our ability to get lost, eradicating randomness and its magic in their wake. Perhaps no one knew this better than France’s early-19th century flâneurs, the idle walkers who happily unspooled their days into the unknown, or the flâneurs’ lowbrow American confreres, the tramp poets of the early 20th century, who surrendered to their surroundings with even more conviction than time-bound monks. In the summer of 1912, the poet Vachel Lindsay set off tramping in a corduroy suit, walking and “meditating on the ways of Destiny,” while preaching the “Gospel of Beauty” to everyone he met...

Our worship of time-management denies the courage these aimless wanderers and idlers demonstrated when stepping out of time. They made the crucial tradeoff: reduced output for liberation. When he died, Henry David Thoreau had published only two books, and “Walden,” then out of print, had been only moderately successful. In the Massachusetts woods, he not only sought solitude, but followed an utterly unconventional timetable, hoeing his beans at 5 a.m. and quitting by noon in order to pursue “other affairs,” like befriending squirrels or lounging next to a spring while reading Homer or the Bhagavad Gita. He chose to “live on the stretch” in order to better savor every moment. “I wanted to live deep and suck out all the marrow of life.”

The stupefying modern obsession with productivity denies the whimsy and the freedom that living fully demands. We must dare to relax our grip on time for a day, or even for an hour, throwing clocks, watches and iPhones over the housetops, untethering ourselves solely for the thrill of not knowing what happens next.

Still alive....

...but in no mood to think or write. 4 hours of rehab exercises every day.

Happy Thanksgiving to all!

MindBlog on medical leave.

I'm heading into knee surgery early tomorrow morning, and may not be feeling in shape to continue doing posts for awhile.

The biology of sacred values.

Frank Rose does a nice piece in the NYTimes, pointing to the work of Gregory Berns and others, on brain correlates of why financial incentives are irrelevant when “sacred values” are at stake. (As in the failure of financial incentives offered by the West in getting Iran to give up its “right” to enrich uranium for “peaceful” uses.) Attempts to offer money to get people to alter strongly held beliefs - with issues like gun control, abortion, Israeli or Palestinian rights to the West Bank of the Jordan - result in moral outrage, feelings of contamination, and a need for moral cleansing. Work by Berns and others suggests we have radically different ways of processing ordinary and sacred beliefs. Berns…

...took M.R.I. images of participants’ brains as he asked them to consider changing their personal beliefs in exchange for money. Would they trade their preference for dogs over cats? What about their belief in God? Would they be willing to kill an innocent person?

When participants were questioned about issues of the dog-or-cat variety, their brain scans showed activity in the parietal cortex — a region that’s thought to be involved in making cost-benefit calculations. But when asked about issues on which they declined to make a trade, entirely different parts of the brain were activated — systems that are associated with telling right from wrong and with storing and retrieving rules. The result, Professor Berns observes, could be a new way to gauge sacred values “that is not solely dependent on self-report.”

Are we going to start running international negotiators through an M.R.I. machine to see where they’re processing the issues? [and determine whether or not someone is faking it when they claim sacred values] Highly unlikely. But results like Professor Berns’s might at least disprove the idea, still held by many, that every belief has its price. Given the intensely negative emotions that financial incentives can trigger, this might be a good lesson to learn.

Here is the abstract from the Berns et al work "The price of your soul: neural evidence for the non-utilitarian representation of sacred values" to which the above is referring. It gives a bit more detail on the brain correlates of sacred values:

Sacred values, such as those associated with religious or ethnic identity, underlie many important individual and group decisions in life, and individuals typically resist attempts to trade off their sacred values in exchange for material benefits. Deontological theory suggests that sacred values are processed based on rights and wrongs irrespective of outcomes, while utilitarian theory suggests that they are processed based on costs and benefits of potential outcomes, but which mode of processing an individual naturally uses is unknown. The study of decisions over sacred values is difficult because outcomes cannot typically be realized in a laboratory, and hence little is known about the neural representation and processing of sacred values. We used an experimental paradigm that used integrity as a proxy for sacredness and which paid real money to induce individuals to sell their personal values. Using functional magnetic resonance imaging (fMRI), we found that values that people refused to sell (sacred values) were associated with increased activity in the left temporoparietal junction and ventrolateral prefrontal cortex, regions previously associated with semantic rule retrieval. This suggests that sacred values affect behaviour through the retrieval and processing of deontic rules and not through a utilitarian evaluation of costs and benefits.

Your fitness age - a simple online calculator

Several popular articles have directed attention to recent work by Nes et al., which suggests that answers to seven simple questions can predict fitness age as well as more exhaustive determinations using peak oxygen intake (VO2) measured on a treadmill, HDL and total cholesterol measurents, accurate determination of body mass index, a lengthy life style questionnaire. Several large scale studies have shown that VO2 max correlates with significantly augmented life spans, and indicates 'fitness age.' They found the simple list of questions predicted VO2 max as well as actual treadmill determinations. I tried their online fitness calculator and discounted its determination that my 71 year old body had the fitness age of a 22-year old. Then I noticed the small detail that the calculator asked for waistline measurement in cm., not inches! Entering the waistline correctly gave me a VO2 max of 40 and fitness age of 59, which is a bit more reasonable. Here is their abstract:

PURPOSE: Cardiorespiratory fitness is suggested to be an important marker of cardiovascular risk but is rarely evaluated in health care settings. In the present study, directly measured peak oxygen uptake (V·O 2peak) from a diverse population of 4637 healthy participants were used to develop and cross-validate a new nonexercise regression model of cardiorespiratory fitness for men and women.

METHODS AND RESULTS: Multivariable regression analysis was used to develop a nonexercise model of cardiorespiratory fitness for men and women separately with V·O 2peak as the outcome. In the final models, 2067 men (mean age = 48.8 yr) and 2193 women (mean age = 47.9 yr) were included, respectively. Cross-validation of the models was done by standard data splitting procedures with evaluation of constant error and total error of a model developed on one sample and cross-validated on another sample. Age, waist circumference, leisure time physical activity, and resting HR, successively, were the most potent predictors of V·O 2peak for both men and women. Together, 61% and 56% of variance in V·O 2peak, for men and women, respectively, were explained by the full models. SEE was 5.70 and 5.14 for the models including men and women, respectively.

CONCLUSIONS: The nonexercise regression model developed in the present study was fairly accurate in predicting V·O 2peak in this healthy population of men and women. The model might be generalized to other healthy populations and might be a valid tool for a rough assessment of cardiorespiratory fitness in an outpatient setting.

Making muscle

Several scientific journals are having a robust and quirky sense of humor these days. I have to pass on this take-off on the Charles Atlas comic advertisements used to describe work by Xu et al. in which a factor obtained from culture of zebrafish embryos is used to induce skeletal muscle differentiation in human induced pluripotent stem cells.

Cell description: The cover catroon tells the story, reported in Xu et al., of an induced pluripotent stem cell (iPSC, shown here in a red t-shirt) that cannot make muscle. When a “bully” researcher tries to steal the postdoctoral fellow working with the iPSC, it's back to the lab, where the fellow uses a zebrafish model to discover chemicals that can turn the iPSC into muscle. Facing down the bully, the postdoctoral fellow rides high on his success. This concept was adapted from Charles Atlas comic advertisements related to bodybuilding. Cover artwork by Athens Qin.

More on long-term benefits of early musical training.

White-Schwoch et al. show that older adults who took music lessons at an early age - the type of instrument doesn't matter - can process the sounds of speech faster than those who did not:

Aging results in pervasive declines in nervous system function. In the auditory system, these declines include neural timing delays in response to fast-changing speech elements; this causes older adults to experience difficulty understanding speech, especially in challenging listening environments. These age-related declines are not inevitable, however: older adults with a lifetime of music training do not exhibit neural timing delays. Yet many people play an instrument for a few years without making a lifelong commitment. Here, we examined neural timing in a group of human older adults who had nominal amounts of music training early in life, but who had not played an instrument for decades. We found that a moderate amount (4–14 years) of music training early in life is associated with faster neural timing in response to speech later in life, long after training stopped (>40 years). We suggest that early music training sets the stage for subsequent interactions with sound. These experiences may interact over time to sustain sharpened neural processing in central auditory nuclei well into older age.

Where musical melodies are represented in our brains.

Here is a fascinating piece by Schindler et al. (open access) showing that musical melodies, or ‘gestalts’ are encoded at very early stages of our auditory processing and are constant through changes of key signature and type of instrument playing.

The perception of a melody is invariant to the absolute properties of its constituting notes, but depends on the relation between them—the melody's relative pitch profile. In fact, a melody's “Gestalt” is recognized regardless of the instrument or key used to play it. Pitch processing in general is assumed to occur at the level of the auditory cortex. However, it is unknown whether early auditory regions are able to encode pitch sequences integrated over time (i.e., melodies) and whether the resulting representations are invariant to specific keys. Here, we presented participants different melodies composed of the same 4 harmonic pitches during functional magnetic resonance imaging recordings. Additionally, we played the same melodies transposed in different keys and on different instruments. We found that melodies were invariantly represented by their blood oxygen level–dependent activation patterns in primary and secondary auditory cortices across instruments, and also across keys. Our findings extend common hierarchical models of auditory processing by showing that melodies are encoded independent of absolute pitch and based on their relative pitch profile as early as the primary auditory cortex.

Why some of us can, or can't, disengage from pain.

Kucyi et al.,  note a beneficial effect of mind wandering and increased default mode network activity on pain suppression. Here is the author's state of the significance of their work:

The mind easily wanders away from mundane tasks, but pain is presumed to automatically capture attention. We demonstrate that individuals differ in how often their minds spontaneously wander away from pain and that these differences are associated with the disruptive effect of pain on cognitive performance. Brain–behavior relationships underscore these individual differences. When people’s minds wander away from pain, there are increased activations of the default mode network (DMN) and strong interactions between the DMN and periaqueductal gray (PAG), an opiate-rich region mediating pain suppression. Individuals with greater tendencies to mind wander from pain have stronger anatomical links and dynamic functional communication between PAG and DMN. These findings provide clinically important clues about why some individuals cannot disengage from pain.

The promises of 'priming'

I've done numerous posts noting psychological experiments on the phenomenon of priming, whose practical application is a major component of behavioral economics. Gary Gutting argues that the significance of priming in our real lives, more complex than the controlled parameters of a psychological experiment, may be overblown in claims that priming experiments provide powerful new tools for influencing human behavior. He starts by noting:

The classic priming experiment was one in which college students had been asked to form various sentences from a given set of words. Those in one group were given words that included several associated with older people (like bingo, gray and Florida). Those in a second group were given words with no such associations. After the linguistic exercise, each participant was instructed to leave the building by walking down a hallway. Without letting the participants know what was going on, the experimenters timed their walks down the hall. They found that those in the group given words associated with old people walked significantly slower than those in the other group. The first group had been primed to walk more slowly.

And, after reviewing claims made for the power of priming techniques to alter our behavior, Gutting notes:

...that priming experiments seldom tell us how important priming is in realistic situations. We know that it has striking effects under highly simplified and controlled laboratory conditions, where the subjects are exposed only to the stimuli that the experimenters provide. But it is very difficult to know how significant priming stimuli (thinking about money, large numbers, abstract questions) would be in a real-life, uncontrolled environment, where all sorts of stimuli might be conflicting with one another. Also, there is seldom any reason to think that even a strong priming effect will last very long. As Jonathan Ellis has noted, even Kahneman ignores these points when, after summarizing the walking-like-the-elderly experiment, he says: “Although you surely were not aware of it, reading this paragraph [which contained many words relating to the elderly] primed you as well. If you had needed to stand up to get a glass of water, you would have been slightly slower than usual to rise from your chair . . . ”

These limits are well illustrated by Richard Thaler and Cass Sunstein’s best-selling book, Nudge. The authors begin with excellent discussions of priming and similar experimental results and then put forward numerous public policy proposals, most of them quite sensible, allegedly inspired by these results. But hardly any of their proposals depend on the results of behavioral economics. Their ideas are mostly a matter of common sense or of strategies long practiced in the business world: in giving people options (regarding decisions like retirement plans or organ donations), make the choice you prefer the default option; provide more or less information on a credit card bill depending on whether you want people to pay just the minimum each month; arrange food in a cafeteria or supermarket so the items you want chosen are most accessible. As Benjamin Friedman pointed out in his review of the book, “we don’t need behavioral economics . . . to think such proposals might be helpful.”

Priming experiments remain important sources of information about the details of how our minds work. It’s possible that they might someday yield valuable techniques for modifying real-world behavior. (Here is one promising if very preliminary example.) But for now claims that they have deep philosophical significance or major practical consequences have scant support.

The serious business of play

Gillian Brown reviews what looks like a very interesting book from Patrick Bateson and Paul Martin "Play, Playfulness, Creativity and Innovation." The look critically evaluates the literature on animal and human play. A few clips from the review:

Some children gain pleasure from climbing trees, some spend hours with building bricks, and others enjoy pretending to be doctors or musicians. In Play, Playfulness, Creativity and Innovation, Patrick Bateson and Paul Martin argue that all of these play activities have in common the generation of novel combinations of actions or thoughts and that early play experiences promote creativity in later life.

...this highly engaging book provides a novel perspective on the role of play activities that apparently lack seriousness. The clarity of prose and diversity of material covered in Play, Playfulness, Creativity and Innovation persuade the reader to reconsider the importance of play in childhood and beyond. For instance, Bateson and Martin point out that childhood play can introduce complexity to the behavioral repertoire and lead to selection for traits that underpin the adoption of novel behavior, thereby altering the evolutionary trajectory of our species. Playful play may be particularly important in generating creativity, and the authors entreat that adults still “have much to gain from deliberately adopting a more playful approach to life.”

To use their quote from George Bernard Shaw, “We don't stop playing because we grow old, we grow old because we stop playing.”

Motor exploration of 5-month old predicts academic achievement at 14 years.

A fascinating part of these observations is the lack of correlation noted in the last sentence of the abstract:. From Bornstein et al.:

A developmental cascade defines a longitudinal relation in which one psychological characteristic uniquely affects another psychological characteristic later in time, separately from other intrapersonal and extrapersonal factors. Here, we report results of a large-scale (N = 374), normative, prospective, 14-year longitudinal, multivariate, multisource, controlled study of a developmental cascade from infant motor-exploratory competence at 5 months to adolescent academic achievement at 14 years, through conceptually related and age-appropriate measures of psychometric intelligence at 4 and 10 years and academic achievement at 10 years. This developmental cascade applied equally to girls and boys and was independent of children’s behavioral adjustment and social competence; mothers’ supportive caregiving, verbal intelligence, education, and parenting knowledge; and the material home environment. Infants who were more motorically mature and who explored more actively at 5 months of age achieved higher academic levels as 14-year-olds.

The quest for personal enhancement - adding self brain stimulation to the toolkit?

I done a series of posts on computer games that can enhance attention, intelligence, memory, navigation and at least partially reverse the effects of aging. (See for example the post on Posit Science's Brain HQ). Interest in brain enhancement by tDCS (trans-cranial direct current stimulation) also has been building exponentially. In previous posts I've noted work showing how his gentle non-invasive technique can alter our sense of fairness, alter belief formation, enhance general intelligence,and mathematical abilities ( with these effects persisting for months), be performed with a do it yourself kit costing around $200, raising both safety and ethical issues. (Even the tDCS units used in research are often little more than a nine-volt battery with two electrodes and a controller for setting the current and the duration of the session. Several YouTube videos show how to make a rough facsimile, but fail to note that applying too much current, for too long, or to the wrong spot on the skull, can be extremely dangerous.) Another post notes a caution that stimulation enhancing one cognitive activity can compromises others.

The New York Times has published two recent article on the technique and the do it yourself approach. One, largely positive, is by Dan Hurley, basically an advertisement for his forthcoming book ‘Smarter: The New Science of Building Brain Power,’ and the second, by Kate Murphy, notes more cautions.

There is little data on the long-term use of tDCS, and some experts worry is that in addition to serious external burns, people who self-administer could permanently damage their brains, impairing cognitive and motor function in subtle and not-so-subtle ways.

“What makes me very nervous about the Foc.us ($249,made by a British firm) and homemade tDCS devices is the intensity and duration of current people are getting,” said Dr. Michael Weisend, a cognitive neuroscientist at Wright State Research Institute in Beaver Creek, Ohio, who conducts tDCS research for the Defense Advanced Research Projects Agency and the Air Force. “We have zero data on long-term use on anybody’s brain, and I have scars to prove that you can burn yourself pretty badly with tDCS.”

I've actually done most of the BrainHQ computer exercises, and note they have clear effects on my attention, perception, and speed....but I get bored after a bit and don't stay with it. Insufficient motivation, I suppose. I'm not about to start dinking around with commercial or home-made tDCS kits, especially given the evidence that boosting one cognitive capacity can compromise others. I think we ought to bloody leave ourselves alone, unless we have notable cognitive impairments than can and should be addressed. I think the self improvement craze that seems to strive for some kind of uber-human is becoming a social pathology...and don't get me started on the marketing of life-extension fantasies.

Generating music during exercise lessens sense of physical effort.

A fascinating bit of work from Fritz et al. makes one wonder whether our human love of music is based in part on its ability to ease physical effort.  They looked not at the effects not of simple passive listening to music during exercise, which is a feature of many gym environments, but of creating music generated by an electronic kit integrated into the internal workings of weight-training machines (such as stair steppers or weight machines with bars pulled up or down).   Subjects in effect became their own disk jockeys, creating sounds that mirrored their physical efforts.  From Reynolds review, the fascinating observation was:

...that most of the volunteers had generated significantly greater muscular force while working at the musically equipped machines than the unmodified ones. They also had used less oxygen to generate that force and reported that their exertions had felt less strenuous. Their movements were also more smooth in general, resulting in a steadier flow of music.

This suggests that:

A similar dynamic may have motivated early humans to whistle or hum while they hunted or tilled and later to raise their voices in song during barn raisings and other intense physical labor.

The abstract of the work:

Here we present a data set demonstrating that musical agency greatly decreases the perceived exertion during strenuous activity. We believe these findings are a major contribution to how we consider the role of music in the emergence of human societies. Furthermore, these findings are timely because they crucially help to understand the therapeutic power of music, a scientific field about to unfold. Although one would expect this workout with musical feedback (jymmin') to be a rather unconventional and dimensionally constrained (each instrument one-dimensionally regulates a musical signal) way to experience musical agency, the experience of the performers suggests an intimate entwinement of ecstatic pleasure and exertion during the performance.

Slaves of the Internet, Unite!

To continue the rant started in last Tuesday's post, let's move on to emphasizing how, in addition to our digital connections compromising our direct human ones, the rewards for writing and thinking have been vastly diminished. Content in real books, magazines, and newspapers that used to generate an income, for creative individuals now is expected for free, as noted by Tim Kreider ("They really do admire your work, just not enough to pay one cent for it") in his very humorous piece "Slaves of the Internet, Unite!"

People who would consider it a bizarre breach of conduct to expect anyone to give them a haircut or a can of soda at no cost will ask you, with a straight face and a clear conscience, whether you wouldn’t be willing to write an essay or draw an illustration for them for nothing.

He notes:

...a side effect of our information economy, in which “paying for things” is a quaint, discredited old 20th-century custom, like calling people after having sex with them. The first time I ever heard the word “content” used in its current context, I understood that all my artist friends and I — henceforth, “content providers” — were essentially extinct. This contemptuous coinage is predicated on the assumption that it’s the delivery system that matters, relegating what used to be called “art” — writing, music, film, photography, illustration — to the status of filler, stuff to stick between banner ads.

Practicalities aside, money is also how our culture defines value, and being told that what you do is of no ($0.00) value to the society you live in is, frankly, demoralizing. Even sort of insulting. And of course when you live in a culture that treats your work as frivolous you can’t help but internalize some of that devaluation and think of yourself as something less than a bona fide grown-up.

My field of expertise is complaining, not answers. I know there’s no point in demanding that businesspeople pay artists for their work, any more than there is in politely asking stink bugs or rhinoviruses to quit it already. It’s their job to be rapacious and shameless. But they can get away with paying nothing only for the same reason so many sleazy guys keep trying to pick up women by insulting them: because it keeps working on someone. There is a bottomless supply of ambitious young artists in all media who believe the line about exposure, or who are simply so thrilled at the prospect of publication that they’re happy to do it free of charge.

Kreider does make a suggestion:

Here, for public use, is my very own template for a response to people who offer to let me write something for them for nothing:

Thanks very much for your compliments on my [writing/illustration/whatever thing you do]. I’m flattered by your invitation to [do whatever it is they want you to do for nothing]. But [thing you do] is work, it takes time, it’s how I make my living, and in this economy I can’t afford to do it for free. I’m sorry to decline, but thanks again, sincerely, for your kind words about my work.

I am impressed Mr. Kreider's old-fashioned courtesy in making such a response. The several requests I get each month to be a 'content provider' for free go straight to the email trash bucket.

Sleep cleans our brains, renews our synapses, consolidates our memories

This bit of work got a flurry of attention recently, but I think is important enough to warrant repeating here.  Xie et al.  have used an elegant two-photon imaging technique to compare awake and sleeping mouse brains. They find that metabolic waste products of neural activity are cleared out of the sleeping brain at a faster rate than during the awake state:

...convective fluxes of interstitial fluid increased the rate of β-amyloid clearance during sleep. Thus, the restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system.

The review of this work by Underwood has a nice graphic of the fluid-filled channels (pale blue) that expand to flush out waste:

The role of sleep in memory consolidation is well known, and further work of Tononi's group has suggested that in rats, sleep maintains an overall synaptic balance, by uniformly dialing down synapses that have expanded their activity during the day. (I have also previously pointed to work on fruit flies by Tononi's group coming to a similar conclusion.)

Work of this sort suggests that the 50-70 million Americans who have insufficient sleep or some kind of sleep disorder (like sleep apnea) are carrying around extra garbage in their brains during the day and have brain synaptic connection that haven't recovered from previous days' activities, both factors that would seem likely to compromise our mental function!

Scary music for Halloween - Dance Macabre

You should have a look at the 13 scariest pieces of classical music for Halloween, assembled by Limelight Magazine. It is hard for me to select a favorite, but I will point to this classic Disney cartoon of Saint-Saens Dance Macabre:

Saint-Saëns’s creepy 1874 tone poem is a Halloween classic, depicting the revelry of the Grim Reaper at midnight every year at this time. With his cursed fiddle, Death summons the dead from their graves to kick up their heals until dawn. In this vintage Disney animation, listen out for the xylophone sound of rattling bones.

Finding a protein linking exercise to brain health

Yet another candidate for a life enhancing drug? ...perhaps a protein that mimics the effect of the protein FNDC5, which is produced by muscular exertion and in turn boosts the level of a brain-health protein, BDNF (brain-derived neurotrophic protein) in the dentate gyrus of the hippocampus. Here is the summary and abstract from Wrann et al. with some technical details:

Highlights

Exercise induces FNDC5 in the hippocampus.

PGC-1α regulates neuronal Fndc5 gene expression in vitro and in vivo.

FNDC5 positively regulates the expression of the important neurotrophin BDNF.

Peripheral delivery of FNDC5 via adenoviral vectors induces Bdnf in the hippocampus.

Summary

Exercise can improve cognitive function and has been linked to the increased expression of brain-derived neurotrophic factor (BDNF). However, the underlying molecular mechanisms driving the elevation of this neurotrophin remain unknown. Here we show that FNDC5, a previously identified muscle protein that is induced in exercise and is cleaved and secreted as irisin, is also elevated by endurance exercise in the hippocampus of mice. Neuronal Fndc5 gene expression is regulated by PGC-1α, and Pgc1a−/− mice show reduced Fndc5 expression in the brain. Forced expression of FNDC5 in primary cortical neurons increases Bdnf expression, whereas RNAi-mediated knockdown of FNDC5 reduces Bdnf. Importantly, peripheral delivery of FNDC5 to the liver via adenoviral vectors, resulting in elevated blood irisin, induces expression of Bdnf and other neuroprotective genes in the hippocampus. Taken together, our findings link endurance exercise and the important metabolic mediators, PGC-1α and FNDC5, with BDNF expression in the brain.