Brain correlates of whether we decide to help others.

Hein et al. find that empathy-related brain responses in the anterior insula predict costly helping of others, that distinct neural responses predict helping in-group and out-group members, and that brain responses predict behavior toward outgroup members better than self-reports:

Little is known about the neurobiological mechanisms underlying prosocial decisions and how they are modulated by social factors such as perceived group membership. The present study investigates the neural processes preceding the willingness to engage in costly helping toward ingroup and outgroup members. Soccer fans witnessed a fan of their favorite team (ingroup member) or of a rival team (outgroup member) experience pain. They were subsequently able to choose to help the other by enduring physical pain themselves to reduce the other's pain. Helping the ingroup member was best predicted by anterior insula activation when seeing him suffer and by associated self-reports of empathic concern. In contrast, not helping the outgroup member was best predicted by nucleus accumbens activation and the degree of negative evaluation of the other. We conclude that empathy-related insula activation can motivate costly helping, whereas an antagonistic signal in nucleus accumbens reduces the propensity to help.

Magic numbers

Anything Daniel Gilbert writes is worth reading, and in that spirit I pass on this Op-Ed bon-bon that asks why a full course of antibiotics usually takes seven days, with stern instructions not to terminate the pills earlier. "Why not six, eight or nine and a half? Does the number seven correspond to some biological fact about the human digestive tract or the life cycle of bacteria?" The answer of course is no....

Seven is a magic number because only it can make a week, and it was given this particular power in 321 A.D. by the Roman emperor Constantine, who officially reduced the week from eight days to seven. The problem isn’t that Constantine’s week was arbitrary — units of time are often arbitrary, which is why the Soviets adopted the five-day week before they adopted the six-day week, and the French adopted the 10-day week before they adopted the 60-day vacation.

The problem is that Constantine didn’t know a thing about bacteria, and yet modern doctors continue to honor his edict. If patients are typically told that every 24 hours (24 being the magic number that corresponds to the rotation of the earth) they should take three pills (three being the magic number that divides any time period into a beginning, middle and end) and that they should do this for seven days, they will end up taking 21 pills.

If even one of those pills is unnecessary — that is, if people who take 20 pills get just as healthy just as fast as people who take 21 — then millions of people are taking at least 5 percent more medication than they actually need. This overdose contributes not only to the punishing costs of health care, but also to the evolution of the antibiotic-resistant strains of “superbugs” that may someday decimate our species. All of which seems like a rather high price to pay for fealty to ancient Rome.

A dog's dish - half empty or half full?

We know that humans vary in their underlying temperament (negative versus positive mood), with ~50% of the variation due to genetic factors.  It turns out that dogs also show variation, with more negative underlying moods predicting the degree of their distress upon separation (Being left a home alone, with the most common separation-related behaviors being vocalising, destruction and toileting). Mendl et al. test for underlying optimism/pessimism involved placing bowls in two rooms. One bowl contained food, while another was empty. After training the dogs to understand that bowls can sometimes be empty, and sometimes full, they began to place bowls in ambiguous locations. Dogs that quickly raced to the locations were more optimistic, and in search of food. Those that did not were deemed pessimistic. The more separation anxiety a dog expressed while in isolation, the more likely the dog was to have a pessimistic reaction.

Earlier retirement, earlier memory decline.

In yet another example of "use it or loose it," Rohwedder and Willis show that the earlier people retire, the more quickly their memory and general cognitive abilities decline. They note two possible models for the cognitive decline: 1.) A "unengaged lifestyle hypothesis" that suggests that the life of a retiree may lack the cognitive stimulation of the former working environment unless deliberate offsetting actions are take. 2.) A “on-the-job” retirement effect, in which mental effort decline as the retirement age approaches (a 50-year-old worker in the United States who expects to work until 65 has a much greater incentive to continue investing in mental capacity than does a worker in Italy who expects to retire at 57.) Here is a summary graph (details are in the article) :

Cognition by Percent Not Working for Pay, 60–64 Year-Old Men and Women, Weighted

Do cell phones cause cancer?

My random browsing of the October issue of Scientific American brought me to this nice summary graphic offered by physicist Bernard Leikind of his article in Skeptic magazine Vol. 15, no. 4 (2010). Utterly basic physical principles show that cell phones (or microwave ovens) could not cause cancer, the energy content of their emitted radiations is orders of magnitude below that required to rupture chemical bonds. (click to enlarge)

What makes groups of people smart?

Woolley and collaborators have studied people working in small groups, investigating why some groups appear to be smarter than others. A given group's performance on any one task did in fact predict its performance on the others, suggesting that groups have a consistent "collective intelligence." Surprisingly, the average intelligence of the individuals in the group was not the best predictor of a group's performance. The degree to which group members were attuned to social cues and their willingness to take turns speaking were more important, as was the proportion of women in the group. Here is their abstract:

Psychologists have repeatedly shown that a single statistical factor—often called "general intelligence"—emerges from the correlations among people's performance on a wide variety of cognitive tasks. But no one has systematically examined whether a similar kind of "collective intelligence" exists for groups of people. In two studies with 699 individuals, working in groups of two to five, we find converging evidence of a general collective intelligence factor that explains a group's performance on a wide variety of tasks. This "c factor" is not strongly correlated with the average or maximum individual intelligence of group members but is correlated with the average social sensitivity of group members, the equality in distribution of conversational turn-taking, and the proportion of females in the group.

A commentary by Greg Miller notes the actual tasks used to evaluate group intelligence:

Teams worked on a variety of tasks, including brainstorming to come up with possible uses for a brick and working collaboratively on problems from a test of general intelligence called Raven's Advanced Progressive Matrices. These problems involve evaluating several shapes arranged in a grid and identifying the missing item that would complete the pattern. The groups also worked on more real-world scenarios, such as planning a shopping trip for a group of people who shared a car. The researchers scored these tests according to predetermined rules that considered several factors (awarding points when shoppers got to buy items on their list, for example). Each participant also took an abbreviated version of the Raven's test as a measure of individual intelligence.

Lecture slides from the "theory of everything" talk.

A comment on the "Theory of Everything" talk referenced by last Friday's post inquired if the whole lecture content was available.  Jim Pawley has been kind enough to forward two PDF files that contain the slides shown at the talk so that those interested could download them.  The first PDF is 10.2 MB in zie,  the second PDF is 2.8 MB in size.

Followup on MindBlog's Istanbul lecture on our subjective "I"

A previous post has pointed to a web text version of the piano recital and lecture I gave at "Cognitive VII", an international cognitive neuroscience meeting held in Istanbul May 18-20 of this year. The organizers indicated they would send a video of the piano performance and lecture, and after a number of tries, I have finally received, and now posted,  a video. It is missing a short bit of audio just after the beginning, and unfortunately deletes the last part of the talk on emotions and the evolution of music.  Still, it gives you a taste of the setting.

Serotonin regulates our moral judgements

Crockett et al. have done some fascinating experiments demonstrating that increased serotonin makes individuals less likely to endorse moral scenarios that result in the infliction of personal harm to others. They examine the effects of a single high dose of the selective serotonin reuptake inhibitor (SSRI) citalopram on moral judgment in healthy volunteers using a set of hypothetical scenarios portraying highly emotionally salient personal and less emotionally salient impersonal moral dilemmas with similar utilitarian outcomes (e.g., pushing a person in front of a train to prevent it from hitting five people and flipping a switch to divert a train to hit one person instead of five people, respectively). Here is their abstract:

Aversive emotional reactions to real or imagined social harms infuse moral judgment and motivate prosocial behavior. Here, we show that the neurotransmitter serotonin directly alters both moral judgment and behavior through increasing subjects’ aversion to personally harming others. We enhanced serotonin in healthy volunteers with citalopram (a selective serotonin reuptake inhibitor) and contrasted its effects with both a pharmacological control treatment and a placebo on tests of moral judgment and behavior. We measured the drugs' effects on moral judgment in a set of moral 'dilemmas' pitting utilitarian outcomes (e.g., saving five lives) against highly aversive harmful actions (e.g., killing an innocent person). Enhancing serotonin made subjects more likely to judge harmful actions as forbidden, but only in cases where harms were emotionally salient. This harm-avoidant bias after citalopram was also evident in behavior during the ultimatum game, in which subjects decide to accept or reject fair or unfair monetary offers from another player. Rejecting unfair offers enforces a fairness norm but also harms the other player financially. Enhancing serotonin made subjects less likely to reject unfair offers. Furthermore, the prosocial effects of citalopram varied as a function of trait empathy. Individuals high in trait empathy showed stronger effects of citalopram on moral judgment and behavior than individuals low in trait empathy. Together, these findings provide unique evidence that serotonin could promote prosocial behavior by enhancing harm aversion, a prosocial sentiment that directly affects both moral judgment and moral behavior.

A commentary by Tost and Meyer-Lindgerg notes:

In a broader context, the work by Crockett et al. supports a number of interesting conclusions. It extends prior evidence suggesting that there are at least two major pharmacological routes that modulate human social behavior: a direct route (“bottom-up”) involving prosocial neuropeptides such as oxytocin and vasopressin, which promote prosocial behaviors such as attachment, empathy, and generosity, and an indirect route (“top-down”) involving serotonin, which delimits antisocial behaviors by reducing negative affect and enhancing the aversiveness of harming others (see figure below). If this is true, functional interactions between these transmitter systems are likely. Consistent with this, Crockett et al. report a pronounced impact of serotonin augmentation on social decision making in subjects with high trait empathy, a finding suggestive of additive prosocial effects of both routes. The study also demonstrates that the effects of serotonin on prosocial behavior are relatively specific and are absent under norepinephrine augmentation with atomoxetine.

Figure - Regulatory circuits of social-emotional information processing in humans. “Top-down” control of the amygdala (AMY) arises from the anterior cingulate cortex (ACG) and ventral medial prefrontal cortex (vmPFC), with the latter being particularly important for the regulation of moral behaviors. “Bottom-up” modulation arises from neurons in the hypothalamus (HYP) expressing the neuropeptides oxytocin and vasopressin, which target distinct neuronal populations in the central amygdala. Projections from the amygdala to the brainstem, via the hypothalamus, regulate the expression of autonomic reactions to social signals. PFC, prefrontal cortex.

A New Theory of Everything?

My Zoology Department colleague Jim Pawley (now retired, as I am) gave a talk to the Chaos and Complex Systems Seminar here at the University of Wisconsin this past Tuesday (I had done a dry run of my Istanbul lecture for this group last May), and I thought his summary of the talk would be of interest to MindBlog readers:

"Climate, energy, and the economy: A new Theory of Everything."
ABSTRACT:
During the industrial revolution, science gained a reputation for mathematical accuracy and precision. Scientific models were effective at predicting the performance of simple systems, from those that spun and wove to those that created the worldwide web. Less appreciated was the fact that these technologies worked ONLY because, during this same period, humankind had also acquired access to a new and immense store of controllable energy. Instead, we were taught that these riches were due to increases in "economic efficiency" and, like the sciences, economics promised a future that was both predictable and bright.

Then a few decades ago, one scientific discipline after another seemed to hit a wall: Although the Uncertainty Principle was at first understood only to affect very small systems, scientists began to realize that some uncertainty was unavoidable, and furthermore that, as it propagates through a complex system, the errors become so large that it is hard to have confidence in any but the broadest of predictions: often only those emerging from thermodynamics.

We had entered the Age of Chaos. Although at first some theorists hoped that "faster computers" might be the answer, in the end computers merely clarified two things: 1) that large changes were exponentially less likely than small ones and 2) that the presence of positive feedback makes it very hard to make any confident predictions, while the relative stability of our environment was based on a variety of negative feedbacks. As time went on, it became evident that most aspects of modern life, from arctic ice to advertising, from politics to preaching and from Wall Street to war, acted as though they too were largely chaotic.

In the real world, the one that now entirely relied on the technology, the advent of the Age of Chaos was not much noticed. Accurate predictions were still expected ("If we can put a man on the Moon...") from a science that now recognized that such things were impossible.

This was unfortunate because, over the past 2 centuries fossil-fuel-powered technology had allowed humans and their domestic animals to multiply until their bodies represented over 98% of the terrestrial vertebrate biomass. More important still, acting either directly, by producing CO2 and other gasses that affect the climate, or indirectly, for instance by the creation of bioactive chemicals, changes to the albedo or barriers to migration, the use of fossil fuel had brought all of the major ecological systems (the atmosphere, forests, oceans etc.) near to the point of collapse.

So now, when society went to science for the precise answers needed to guide a response to these challenges, science had few simple answers, and most of these were from from thermodynamics: There is no free lunch. Use less energy or else.

Previous meetings of this forum have addressed many of these matters individually or in small groups. I have the feeling that the fact that so many of these essential but chaotic and interacting factors are approaching a critical point simultaneously adds an additional level of concern. Perhaps we can use what we have learned about chaotic systems to improve the odds? I hope to get some ideas. Or perhaps to raise the threat level...

The science of us...

I pass on this clip from the Oct. 8 issue of Science Magazine, struck by the verse that brings home the fact that most of the cells in our body are 'foreign' bacteria:

They Said It

What am I in truth?
What am I in reality,
When only one in 10 of my cells
Is genetically humanity?

—From "Bacteria," one of the 20-odd songs celebrating the universe on scales from angstroms to astronomical units in "Powers of Ten," a choral work by composer David Haines. More than 200 singers from the Washington, D.C., area are set to perform the work on 10 October at the University of Maryland, College Park, kicking off the first inaugural USA Science & Engineering Festival. See

www.usasciencefestival.org.

Exercise improves executive function in our aging brains

A group of collaborators has looked at functional connectivity measured by fMRI in ~65 year old adults before and after their separation for one year into exercise (walking, 30 individuals) and non-exercise (35 individuals) groups. In the exercising group they find increased functional connectivity associated with greater improvement in executive function, providing evidence for exercise-induced functional plasticity in large-scale brain systems in older brains. Here is their whole abstract.

Research has shown the human brain is organized into separable functional networks during rest and varied states of cognition, and that aging is associated with specific network dysfunctions. The present study used functional magnetic resonance imaging (fMRI) to examine low-frequency (0.008 to 0.08 Hz) coherence of cognitively relevant and sensory brain networks in older adults who participated in a 1-year intervention trial, comparing the effects of aerobic and non-aerobic fitness training on brain function and cognition. Results showed that aerobic training improved the aging brain’s resting functional efficiency in higher-level cognitive networks. One year of walking increased functional connectivity between aspects of the frontal, posterior, and temporal cortices within the Default Mode Network and a Frontal Executive Network, two brain networks central to brain dysfunction in aging. Length of training was also an important factor. Effects in favor of the walking group were observed only after 12 months of training, compared to non-significant trends after 6 months. A non-aerobic stretching and toning group also showed increased functional connectivity in the DMN after 6 months and in a Frontal Parietal Network after 12 months, possibly reflecting experience-dependent plasticity. Finally, we found that changes in functional connectivity were behaviorally relevant. Increased functional connectivity was associated with greater improvement in executive function. Therefore the study provides the first evidence for exercise-induced functional plasticity in large-scale brain systems in the aging brain, using functional connectivity techniques, and offers new insight into the role of aerobic fitness in attenuating age-related brain dysfunction.

A presumed cognitive divide between monkeys and ourselves disappears

In trying to understand the sequential evolutionary steps that led to our human style self awareness, much has been made of the fact that monkeys appear to fail the mirror self recognition task, while chimpanzees, along with a few other species (including dolphins, some birds, and elephants) pass the test. My Wisconsin colleague Luis Populin now finds evidence to the contrary in the rhesus monkeys used in his experiments:

Self-recognition in front of a mirror is used as an indicator of self-awareness. Along with humans, some chimpanzees and orangutans have been shown to be self-aware using the mark test. Monkeys are conspicuously absent from this list because they fail the mark test and show persistent signs of social responses to mirrors despite prolonged exposure, which has been interpreted as evidence of a cognitive divide between hominoids and other species. In stark contrast with those reports, the rhesus monkeys in this study, who had been prepared for electrophysiological recordings with a head implant, showed consistent self-directed behaviors in front of the mirror and showed social responses that subsided quickly during the first experimental session. The self-directed behaviors, which were performed in front of the mirror and did not take place in its absence, included extensive observation of the implant and genital areas that cannot be observed directly without a mirror. We hypothesize that the head implant, a most salient mark, prompted the monkeys to overcome gaze aversion inhibition or lack of interest in order to look and examine themselves in front of the mirror. The results of this study demonstrate that rhesus monkeys do recognize themselves in the mirror and, therefore, have some form of self-awareness. Accordingly, instead of a cognitive divide, they support the notion of an evolutionary continuity of mental functions.

Why indiscretions appear youthful.

Benedict Carey does a nice summary article on studies that show that people date their memories of moral failings about 10 years earlier, on average, than their memories of good deeds. Here is the abstract of the paper he reviews:

Our autobiographical self depends on the differential recollection of our personal past, notably including memories of morally laden events. Whereas both emotion and temporal recency are well known to influence memory, very little is known about how we remember moral events, and in particular about the distribution in time of memories for events that were blameworthy or praiseworthy. To investigate this issue in detail, we collected a novel database of 758 confidential, autobiographical narratives for personal moral events from 100 well-characterized healthy adults. Negatively valenced moral memories were significantly more remote than positively valenced memories, both as measured by the valence of the cue word that evoked the memory as well as by the content of the memory itself. The effect was independent of chronological age, ethnicity, gender or personality, arguing for a general emotional bias in how we construct our moral autobiography.

A Brahms Intermezzo

Here is the second of two Brahms piano pieces that I recently recorded. The first was posted last Tuesday.

Embodyment of our emotions in our brains.

A long standing issue in the neuroscience of emotions has been whether signals from our body (i.e. afferent visceral signals via interoceptive afferent fibers that monitor the physiological state of our internal organs) are essential for the unique experiences of distinct emotions, or whether these signals are too crude and undifferentiated to enable the wide variety of emotional feeling we can have. This issue has been difficult to resolve in the absence of methods to measure and integrate central neural responses, peripheral physiological responses, and subjective experience. Harrison et al have now used a combination of functional magnetic resonance imaging (fMRI) and simultaneous recording of autonomic influences on two independent organ systems (heart and stomach) during the experience of two different forms of disgust: core and body boundary violation disgust, induced, respectively by participants watching videos of people eating disgusting food, or of a surgical operation. Although both scenes produced strong disgust, these feelings were associated with distinct gastric and cardiac effects as well as differential activation in the insula and other brain regions. Thus, interoception could contribute to the perception of emotion. The magnitude of subjectively experienced disgust, regardless of disgust form, correlated with anterior insula activity. I pass on one figure from the paper that shows areas of the insula selectively activated by core versus body boundary violation disgust:

Figure - Insula activations to core and BBV disgust. A, Core greater than BBV disgust. B, BBV greater than core disgust. Contrast estimates show activations in circled right ventral and dorsal insula, respectively, in order (left to right): high core, low core, high BBV, and low BBV disgust.

This Year's Ig Nobels

ScienceNow does a summary of this year's ignoble prizes.  This year's ceremony was an exception for including a cash prize: A $100 trillion note from Zimbabwe. (The note's actual value: nada.) One prize returns again to work that I have mentioned in a previous post, showing that slime molds can do as good or better a job than humans in designing transport networks. Here is a list of some of the others:

Engineering: Marine biologist Karina Acevedo-Whitehouse of the Zoological Society of London and colleagues for their method of collecting samples of whale snot using a remote-controlled helicopter.

Medicine: Psychologist Simon Rietveld of the University of Amsterdam in the Netherlands and colleagues for discovering that asthma symptoms can be successfully treated with roller-coaster rides.

Physics: Public health researcher Lianne Parkin of the University of Otago in New Zealand and colleagues for proving that wearing socks on the outside of shoes reduces slips on icy surfaces.

Peace: Psychologist Richard Stephens of Keele University in the United Kingdom and colleagues for demonstrating that swearing alleviates pain.

Public health: Microbiologist Manuel Barbeito of the Industrial Health and Safety Office at Fort Detrick, Maryland, and colleagues for determining that microbes flourish in the beards of scientists.

Economics: The executives of Goldman Sachs, AIG, Lehman Brothers, Bear Stearns, Merrill Lynch, and Magnetar "for creating and promoting new ways to invest money--ways that maximize financial gain and minimize financial risk for the world economy, or for a portion thereof."

Chemistry: Engineer Eric Adams of the Massachusetts Institute of Technology in Cambridge and colleagues for disproving the belief that oil and water don't mix.

Management: Social scientist Alessandro Pluchino of the University of Catania in Italy and colleagues for mathematically demonstrating that organizations can increase efficiency by giving people promotions at random.

Biology: Biologist Libiao Zhang of the University of Bristol in the United Kingdom and colleagues for their study of fellatio in fruit bats.

The fraying thread of civil society

I wanted to pass on this link to an article in this morning's NYTimes by Mat Bai that seems especially cogent. It deals with the independent voters whose actions appear to be pivotal in the coming elections. He describes the convening by three (non-sponsored) political and corporate marketing consultants of small focus groups of self-identified independent voters who are friends or relatives of one another, meeting in a participant’s living room.

The dominant theme of the discussion, in which jobs and taxes came up only in passing, seemed to be the larger breakdown of civil society — the disappearance of common courtesy, the relentless stream of data from digital devices, the proliferation of lawsuits and the insidious influence of media on their children...One woman described a food fight at the middle school that left a mess school employees were obliged to clean up, presumably because the children couldn’t be subjected to physical labor. A man complained about drivers who had grown increasingly hostile and inconsiderate on the roads, which drew nods of assent all around...The economy was discussed mostly in connection with these other stresses. “We all think that if we had a lot of money,” one woman said, “everything would slow down and we could enjoy ourselves.”

These voters did not hate politicians. They simply saw both parties, along with the news media and big business, as symptoms of the larger societal ailment. And this underlying perception, that politicians in Washington conduct themselves just as childishly and with the same lack of accountability as the students throwing chicken casserole in the lunchroom, may well be the principal emotion behind the electorate’s propensity to vote out whoever holds power.

Brain correlates of introspective accuracy.

Knowing whether confidence predicts accuracy would be very useful, for example, in evaluating conflicting courtroom testimony in statements from witnesses who seem more or less confident. In a fascinating article, Fleming et al. find a relationship between the brain scans of people obtained by magnetic resonance imaging (MRI) and how seriously we should take their expressed level of confidence. They use a simple perceptual task, detecting the contrast between light and dark bars in a grating, which makes it possible to obtain both an objective measure of how accurate subjects are and a subjective measure of how confident they are in their judgments. They construct a measure of how accurate subjects are in their confidence judgments. The capacity for introspection, which can be regarded as one facet of metacognition (thinking about thinking), is shown to vary across individuals and to correlate positively with the gray matter volume of the frontopolar cortex (the frontmost region of the brain) and also with white matter in the tracts of the corpus callosum that connect these regions in the left and right hemispheres. From the abstract:

We show that introspective ability is correlated with gray matter volume in the anterior prefrontal cortex, a region that shows marked evolutionary development in humans. Moreover, interindividual variation in introspective ability is also correlated with white-matter microstructure connected with this area of the prefrontal cortex. Our findings point to a focal neuroanatomical substrate for introspective ability, a substrate distinct from that supporting primary perception.

Mindblog does another anti-aging experiment.

I find myself both spooked and sparked by my second foray into anti-aging chemistry (the first being the unsuccessful resveratrol dalliance described in a previous post.) A colleague pointed me to work of Bruce Ames and collaborators (also here) which has led to the marketing by Juvenon of a dietary supplement containing Acetyl L-carnitine, alpha-lipoic acid, and the B-vitamin biotin. Experiments on rats show that these compounds reverse the age related decay in energy metabolism in mitochondria and also inhibit oxidative damage to mitochondrial lipids. So... the idea is that these supplements might energize and juice you up a bit.  The Juvenon supplement contains (per day) 600 mcg biotin, 2000 mg of acetyl-L-carnitine, and 800 mg of alpha lipoic acid.  I though $40 was a bit steep for a 30 day supply, and so I bought the equivalent supplements from Swanson Health Products for significantly less money.  I decided to take 600 mg of the carnitine/day, 1000 mg/day of the alpha lipoic acid,  and 1000 mcg/day of biotin,  half at breakfast, half at lunch (by the way, this is slightly less than 1% of the levels used in the rat experiments.) From the homework I have done so far, the levels of these supplements being taken have no documented adverse side effects.

The results?  Well.... sufficiently dramatic that I really can't credit that it is all a placebo effect,  because I go into any such experiment as an unbeliever... The first several days I felt a phase change, a  step up in energy level and kinetic energy that made me like a 20-something again, a bit incredulous, as in "whoa.. where did this come from."  With both brain and body feeling like an automobile engine running at 2,000 r.p.m. even when it was not in gear,  I cut the levels of the supplements by a half after three days.   After another three days of energy I didn't know what to do with,  generating what felt like excess brain and body "noise,"  I stopped the supplement,  deciding that my normal fairly robust daily routines (including daily gym work or swimming, running, or weights) apparently had all the energy they needed.

Any experiences or references from blog readers would be appreciated.