Monday, August 31, 2009
A common belief in the United States is that the media exhibit a liberal bias, which generally aligns them with Democratic programs and politicians, in their reporting of the news and in their selection of what news to report on. In fact, one study estimates the effect of Fox News Channel, which was launched about a decade ago and is generally more conservative than other television outlets, as having increased the Republican share of the vote by half a percentage point.
One month before the November 2005 gubernatorial election in Virginia, Gerber et al. carried out a randomized field study in which several thousand households that did not already receive a daily newspaper were given trial subscriptions to either the Washington Post (liberal) or the Washington Times (conservative). Post-election telephone interviews established that receiving either newspaper had little impact on factual knowledge (such as Harriet Miers being a Supreme Court nominee) or political attitudes (such as President Bush's approval rating). What was affected was voter turnout (as measured by administrative records) and, surprisingly, actual voter choice, with both sets of newspaper-receiving households favoring the Democratic candidate by about seven percentage points.
In the face of uncertainty, how do we choose between maintaining our current strategy or trying new strategies? A study From Frank et al. shows that a gene controlling prefrontal dopamine function is predictive of uncertainty-driven exploration:
The basal ganglia support learning to exploit decisions that have yielded positive outcomes in the past. In contrast, limited evidence implicates the prefrontal cortex in the process of making strategic exploratory decisions when the magnitude of potential outcomes is unknown. Here we examine neurogenetic contributions to individual differences in these distinct aspects of motivated human behavior, using a temporal decision-making task and computational analysis. We show that two genes controlling striatal dopamine function, DARPP-32 (also called PPP1R1B) and DRD2, are associated with exploitative learning to adjust response times incrementally as a function of positive and negative decision outcomes. In contrast, a gene primarily controlling prefrontal dopamine function (COMT) is associated with a particular type of 'directed exploration', in which exploratory decisions are made in proportion to Bayesian uncertainty about whether other choices might produce outcomes that are better than the status quo. Quantitative model fits reveal that genetic factors modulate independent parameters of a reinforcement learning system.
Friday, August 28, 2009
A fascinating and sobering piece from Miller et al in the new issue of Proc. Nat. Acad. Sci.:
Children reared in unfavorable socioeconomic circumstances show increased susceptibility to the chronic diseases of aging when they reach the fifth and sixth decades of life. One mechanistic hypothesis for this phenomenon suggests that social adversity in early life programs biological systems in a manner that persists across decades and thereby accentuates vulnerability to disease. Here we examine the basic tenets of this hypothesis by performing genome-wide transcriptional profiling in healthy adults who were either low or high in socioeconomic status (SES) in early life. Among subjects with low early-life SES, there was significant up-regulation of genes bearing response elements for the CREB/ATF family of transcription factors that conveys adrenergic signals to leukocytes, and significant down-regulation of genes with response elements for the glucocorticoid receptor, which regulates the secretion of cortisol and transduces its antiinflammatory actions in the immune system. Subjects from low-SES backgrounds also showed increased output of cortisol in daily life, heightened expression of transcripts bearing response elements for NF-κB, and greater stimulated production of the proinflammatory cytokine interleukin 6. These disparities were independent of subjects' current SES, lifestyle practices, and perceived stress. Collectively, these data suggest that low early-life SES programs a defensive phenotype characterized by resistance to glucocorticoid signaling, which in turn facilitates exaggerated adrenocortical and inflammatory responses. Although these response patterns could serve adaptive functions during acute threats to well-being, over the long term they might exact an allostatic toll on the body that ultimately contributes to the chronic diseases of aging.
I have been reading, in fits and starts, Jonah Leher's "Proust was a Neuroscientist," and just came across a review by Jonathan Bates that is consonant with my own opinions of the book:
The book is an elegant collection of essays—like Davis's extended essay, written in partial homage to William James—in which a range of 19th and early 20th century artists are shown to have discovered truths about the human mind ‘that science is only now rediscovering’ (pvii). Thus we get Walt Whitman on the ’embodied‘ nature of emotion (anticipating Antonio Damasio's work, which is so inspiring to scholars on the humanist side of the two cultures divide), Escoffier on the essence of taste, Cézanne on the process of sight, Gertrude Stein on the structure of language and so on. The focus is very much on the innovations of modernism. It would have been equally possibly to write a series of studies based on earlier anticipations—Wordsworth rather than Proust on memory, Keats rather than Whitman on the body—but that does not diminish the sharpness of the insights.
The book is worth its price for the chapter on Proust alone. This begins with some fairly obvious points, for instance that Proust was right to suppose that taste and smell are more powerful triggers for memory than sight, hearing and the self-conscious work of trying to remember something because they are ‘the only senses that connect directly to the hippocampus, the centre of the brain's long-term memory’ (p80). This explains the effect of the famous madeleine dipped into a cup of tea in Du côté de chez Swann. But Lehrer rapidly moves on to the much more interesting question of memory's fallibility. The key to A la Recherche du Temps Perdu is that past time is forever lost and that the search for it will always end in failure because of the fallibility of memory.
Lehrer contends that Proust intuited something that experimentation has now confirmed:
‘A memory is only as real as the last time you remembered it. The more you remember something, the less accurate the memory becomes ... every time we remember anything, the neuronal structure of the memory is delicately transformed, a process called reconsolidation ... So the purely objective memory, the one ‘true’ to the original taste of the madeleine, is the one memory you will never know. The moment you remember the cookie's taste is the same moment you forget what it really tasted like’ (p85).
Lehrer backs up this proposition with a fascinating account of some experiments on rats at New York University (Nader et al., 2000Go, 2004). Admittedly, this begs the question of the degree to which human memories work like rat memories. But the evidence does seem to support the profoundly Proustian idea that a memory is not like a photograph stored somewhere in the brain. Rather, ‘every memory is inseparable from the moment of its recollection: there simply is no way to describe the past without lying. Our memories are not like fiction. They are fiction’ (p88). This was a thought that Wordsworth got to before Proust: in his great autobiographical poem The Prelude, he wrestled with the question of the degree to which the feelings associated with his memories were invented by the very act of remembering.
Lehrer reminds us that the average half life of a brain protein is only 14 days. ‘The mind is in a constant state of reincarnation’ (p91). If the brain is constantly being reconstituted out of new cells, how do memories last? The chapter concludes with a tentative answer from Kausik Si's hypothesis that the ‘synaptic mark’ of memory is to be found in the cyptoplasmic polyadenylation element binding protein, which behaves very like a prion (Si et al., 2003Go). As is well-known from the huge challenge of research on mad cow disease, prions are virtually indestructible and ‘display an astonishing amount of plasticity’ (p93). Si's work remains controversial but it is, Lehrer claims, ‘the first hypothesis that begins to explain how sentimental ideas endure’. And the model is indeed remarkably Proustian.
....whilst there are new things about Shakespeare and Proust to be learnt by humanities scholars from brain science, so there are old things which Shakespeare and Proust can teach to brain scientists.
An interesting article describing work of Harvard Business School assistant professor Anat Keinan, in collaboration with Columbia Business School professor Ran Kivetz.
Keinan and Kivetz set out to see if they could observe, in formal studies, people overestimating discipline’s payoff and underestimating future feelings of having missed out. Time after time, when subjects were asked to recall situations in which they had to choose between work and pleasure, their responses emulated those of the Columbia doctoral students. More of the subjects who’d chosen play over work recently expressed regret, but those numbers reversed for choices made in the distant past. For instance, college students said they’d spent too much time relaxing during a recent winter break, but when they considered the previous year’s break, they said they’d spent too much time studying and working.
They call the habit of overestimating the benefits one will receive in the future from making responsible decisions now "hyperopia" - the name, drawn from ophthalmology, means “farsightedness.” It works to our detriment by driving people to underconsume precisely those products and experiences that they enjoy the most.
Thursday, August 27, 2009
Tierney does an interesting piece on work by Kochanska and colleagues showing how guilt in children, which usually appears during their second year, develops along side effortful self-control to inhibit impulsive behaviors that might hurt themselves or others. A deficit in either can be compensated by increased strength of the other, but a deficit in both guilt behavior and self-control increases the probability of sociopathic behaviors. To prevent guilt over a particular bad event from generalizing into shame (which has repeatedly been found to be unhealthy, as in "I'm a bad person"), it is important to have some sort of atonement process to round off the process. The article gives interesting examples of this process.
I'm a physically active person, and feel strange if I have missed a day of going to the university gym to swim, run, or do weights. At 67 years of age I also fret about the point at which strengthening and healthy changes being to be overshadowed by inflamatory reactions in body joints. Thus I was struck by this piece in the NYTimes, reporting exactly the opposite of the conventional wisdom, namely that running is good for your knees. The article contains a link to some neat exercises for strengthening muscle than can take some of the load off the knee joint itself.
Richie Davidson, Ned Kalin, and their collaborators here at Wisconsin make interesting observations on a groups of rhesus monkeys in which the relationship between regional brain glucose metabolism and anxious temperament had previously been established. Here is their abstract:
The serotonin transporter (5-HTT) plays a critical role in regulating serotonergic neurotransmission and is implicated in the pathophysiology of anxiety and affective disorders. Positron emission tomography scans using [11C]DASB [11C]-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile] to measure 5-HTT availability (an index of receptor density and binding) were performed in 34 rhesus monkeys in which the relationship between regional brain glucose metabolism and anxious temperament was previously established. 5-HTT availability in the amygdalohippocampal area and bed nucleus of the stria terminalis correlated positively with individual differences in a behavioral and neuroendocrine composite of anxious temperament. 5-HTT availability also correlated positively with stress-induced metabolic activity within these regions. Collectively, these findings suggest that serotonergic modulation of neuronal excitability in the neural circuitry associated with anxiety mediates the developmental risk for affect-related psychopathology.
Wednesday, August 26, 2009
Grieg Lyric Pieces Op 62 no 5, Phantom
While I notice that my short term memory is getting worse, I have felt (through my practicing and learning of new piano pieces) that my procedural learning capabilities are improving with age. In this light I found these observations from Brown et al. interesting:
It is well known that certain cognitive abilities decline with age. The ability to form certain new declarative memories, particularly memories for facts and events, has been widely shown to decline with advancing age. In contrast, the effects of aging on the ability to form new procedural memories such as skills are less well known, though it appears that older adults are able to acquire some new procedural skills over practice. The current study examines the effects of normal aging on procedural memory more closely by comparing the effects of aging on the encoding or acquisition stage of procedural learning versus its effects on the consolidation, or between-session stage of procedural learning. Twelve older and 14 young participants completed a sequence-learning task (the Serial Reaction Time Task) over a practice session and at a re-test session 24 hours later. Older participants actually demonstrated more sequence skill during acquisition than the young. However, older participants failed to show skill improvement at re-test as the young participants did. Age thus appears to have a differential effect upon procedural learning stages such that older adults' skill acquisition remains relatively intact, in some cases even superior, compared to that of young adults, while their skill consolidation may be poorer than that of young adults. Although the effect of normal aging on procedural consolidation remains unclear, aging may actually enhance skill acquisition on some procedural tasks.
In theory, the public overwhelmingly supports health care reform. James Surowiecki has a piece in the current New Yorker that suggests several reasons that they go all wobbly when it actually comes to making fundamental change. First is the "endowment effect" - the mere fact that you have something leads you to overvalue it. If people have insurance, most will value it highly, no matter how flawed the current system. Talk of changing the system accentuates the endowment effect. Last year a poll found that only 29% of likely voters found the US health care system good or excellent. When asked the same question last month 48% rated it highly, and health care delivery hadn't changed that much in the intervening 11 months! Adding to the endowment effect is the status quo bias. Most people are inclined to keep things the way they are. We feel the pain of losses more than we enjoy the pleasures of gain. So, when we think about change we focus more on what we might lose than what we might gain. Most people who don't feel good about the present system still feel anxious about whatever will replace it.
Surowiecki suggests that the key may be to work with, rather than against, people's desire for security. This is why Obama has repeatedly stressed that if people like the health care they have, they can keep it. Also, changing the system so that people can get affordable health care, while banning bad behavior on the part of insurance companies, will make it more likely that people can preserve their current level of coverage. The message should be that if we want to protect the status quo, we need to reform it.
Tuesday, August 25, 2009
I've mentioned the work of Lyubomirsky in a previous post. She now has collaborated with people at Signal Patterns, a developer of psychology-based web and mobile applications, to generate an iPhone App meant to facilitate the basic exercises outlined in her book.
There seems to be a surge recently in articles on stress in the brain. Here I point you to two pieces: work from McEwen and collaborators showing that acute stress enhances glutamatergic transmission in prefrontal cortex and facilitates working memory, and Admon et al.'s study of new recruits to the Israeli military that shows that an individual's amygdalar reactivity (i.e., predated neural sensitivity) before stress is predictive of later vulnerability to stress and stress symptoms.
Strimling et al. develop a simple model to test the most popular recent evolutionary hypothesis about culture, memetics, which maintains that cultural evolution is the playing field of selfish memes. Simply put, the idea is that the success of cultural traits is determined by their inherent power to spread between human minds. The analysis, based on their model which considers the diffusion and retention of cultural variants (ideas), suggests that the possibility to predict long-term cultural evolution by some success index, analogous to biological fitness, depends on whether individuals have few or many opportunities to learn. Their abstract:
Although genetic information is acquired only once, cultural information can be both abandoned and reacquired during an individual's lifetime. Therefore, cultural evolution will be determined not only by cultural traits' ability to spread but also by how good they are at sticking with an individual; however, the evolutionary consequences of this aspect of culture have not previously been explored. Here we show that repeated learning and multiple characteristics of cultural traits make cultural evolution unique, allowing dynamical phenomena we can recognize as specifically cultural, such as traits that both spread quickly and disappear quickly. Importantly, the analysis of our model also yields a theoretical objection to the popular suggestion that biological and cultural evolution can be understood in similar terms. We find that the possibility to predict long-term cultural evolution by some success index, analogous to biological fitness, depends on whether individuals have few or many opportunities to learn. If learning opportunities are few, we find that the existence of a success index may be logically impossible, rendering notions of “cultural fitness” meaningless. On the other hand, if individuals can learn many times, we find a success index that works, regardless of whether the transmission pattern is vertical, oblique, or horizontal.
Monday, August 24, 2009
As summer winds down, I've decided to record a few more Grieg lyrical pieces.
It is generally thought that imitation is one mechanism through which cultural learning occurs. When others mimic us, we like them more, empathize with them more, and are more helpful and generous toward them. Recent work with capuchin monkeys suggests that imitation may of general importance in enhancing prosocial social behaviors, suggesting that the social consequences of mimicry may have deeper evolutionary roots than previously thought. Paukner et al. find that these animals behave in a more affiliative manner, as assessed by direction of gaze, physical proximity, and token exchange, toward humans who imitate them as compared to humans who perform the same movements, but not at the same time.
The September issue of the Scientific American (the 'Origins Issue') has an article by Marc Hauser in which he makes a list of what he considers distinctive human competencies (enter 'Hauser' in the search box in the left column to see my previous posts mentioning Hauser's work). Here is a clip from the article:
Although humans share the vast majority of their genes with chimps, studies suggest that small genetic shifts that occurred in the human lineage since it split from the chimp line produced massive differences in computational power. This rearranging, deleting and copying of universal genetic elements created a brain with four special properties. Together these distinctive characteristics, which I have recently identified based on studies conducted in my lab and elsewhere, constitute what I term our humaniqueness. The first such trait is generative computation, the ability to create a virtually limitless variety of “expressions,” be they arrangements of words, sequences of notes, combinations of actions, or strings of mathematical symbols. Generative computation encompasses two types of operation, recursive and combinatorial. Recursion is the repeated use of a rule to create new expressions. Think of the fact that a short phrase can be embedded within another phrase, repeatedly, to create longer, richer descriptions of our thoughts– for example, the simple but poetic expression from Gertrude Stein: “A rose is a rose is a rose.” The combinatorial operation, meanwhile, is the mixing of discrete elements to engender new ideas, which can be expressed as novel words (“Walkman”) or musical forms, among other possibilities.
The second distinguishing characteristic of the human mind is its capacity for the promiscuous combination of ideas. We routinely connect thoughts from different domains of knowledge, allowing our understanding of art, sex, space, causality and friendship to combine. From this mingling, new laws, social relationships and technologies can result, as when we decide that it is forbidden [moral domain] to push someone [motor action domain] intentionally [folk psychology domain] in front of a train [object domain] to save the lives [moral domain] of five [number domain] others.
Third on my list of defining properties is the use of mental symbols. We can spontaneously convert any sensory experience—real or imagined— into a symbol that we can keep to ourselves or express to others through language, art, music or computer code.
Fourth, only humans engage in abstract thought. Unlike animal thoughts, which are largely anchored in sensory and perceptual experiences, many of ours have no clear connection to such events. We alone ponder the likes of unicorns and aliens, nouns and verbs, infinity and God. Although anthropologists disagree about exactly when the modern human mind took shape, it is clear from the archaeological record that a major transformation occurred during a relatively brief period of evolutionary history, starting approximately 800,000 years ago in the Paleolithic era and crescendoing around 45,000 to 50,000 years ago. It is during this period of the Paleolithic, an evolutionary eyeblink, that we see for the first time multipart tools; animal bones punctured with holes to fashion musical instruments; burials with accoutrements suggesting beliefs about aesthetics and the afterlife; richly symbolic cave paintings that capture in exquisite detail events of the past and the perceived future; and control over fire, a technology that combines our folk physics and psychology and allowed our ancestors to prevail over novel environments by creating warmth and cooking foods to make them edible.
Friday, August 21, 2009
Following this week's (accidental) emphasis on stress and its effects, I'll point out an article by Henckens et al. on the enhancement of memory by stress, apparently through hypervigilant sensory processing, even though hippocampal activation is diminished. (Chronic stress is known to damage and shrink the hippocampus):
Stressful, aversive events are extremely well remembered. Such a declarative memory enhancement is evidently beneficial for survival, but the same mechanism may become maladaptive and culminate in mental diseases such as posttraumatic stress disorder (PTSD). Stress hormones are known to enhance postlearning consolidation of aversive memories but are also thought to have immediate effects on attentional, sensory, and mnemonic processes at memory formation. Despite their significance for our understanding of the etiology of stress-related mental disorders, effects of acute stress at memory formation, and their brain correlates at the system scale, remain elusive. Using an integrated experimental approach, we probed the neural correlates of memory formation while participants underwent a controlled stress induction procedure in a crossover design. Physiological (cortisol level, heart rate, and pupil dilation) and subjective measures confirmed acute stress. Remarkably, reduced hippocampal activation during encoding predicted stress-enhanced memory performance, both within and between participants. Stress, moreover, amplified early visual and inferior temporal responses, suggesting that hypervigilant processing goes along with enhanced inferior temporal information reduction to relay a higher proportion of task-relevant information to the hippocampus. Thus, acute stress affects neural correlates of memory formation in an unexpected manner, the understanding of which may elucidate mechanisms underlying psychological trauma etiology.
Mair describes work by Viczian et al. who show that frog cells forced to express seven transcription factor genes form functioning eyes in tadpoles. (The transcription factors are proteins that bind to DNA and turn on a panel of genes involved in building the eye).
Check out this Illusion Sciences blog from Arthur Shapiro.
Thursday, August 20, 2009
Sousa's group makes interesting observations on brain changes caused by chronic stress. There is a distinctive shift away from adaptive goal directed decision making towards habitual routines that can persist in spite of being inappropriate. Chronic stress actually causes opposing structural changes in the associative and sensorimotor corticostriatal circuits underlying these different behavioral strategies, with atrophy of medial prefrontal cortex and the associative striatum and hypertrophy of the sensorimotor striatum. The change is reversible: rats given a four week vacation from the bullying and tasers used for the stress-out reverted to normal behaviors. Angier's review points out the obvious relevance of such observation to our human behavior:
If after a few months’ exposure to our David Lynch economy, in which housing markets spontaneously combust, coworkers mysteriously disappear and the stifled moans of dying 401(k) plans can be heard through the floorboards, you have the awful sensation that your body’s stress response has taken on a self-replicating and ultimately self-defeating life of its own, congratulations. You are very perceptive. It has....Robert Sapolsky, a neurobiologist who studies stress at Stanford University School of Medicine, said, “This is a great model for understanding why we end up in a rut, and then dig ourselves deeper and deeper into that rut.”...The truth is, Dr. Sapolsky said, “we’re lousy at recognizing when our normal coping mechanisms aren’t working. Our response is usually to do it five times more, instead of thinking, maybe it’s time to try something new.”With regard to the reversibility of the behavior:
According to Bruce S. McEwen, head of the neuroendocrinology laboratory at Rockefeller University, the new findings offer a particularly elegant demonstration of a principle that researchers have just begun to grasp. “The brain is a very resilient and plastic organ,” he said. “Dendrites and synapses retract and reform, and reversible remodeling can occur throughout life.”
The stress response is essential for maneuvering through a dynamic world — for dodging a predator or chasing down prey, swinging through the trees or fighting off disease — and it is itself dynamic. As we go about our days, Dr. McEwen said, the biochemical mediators of the stress response rise and fall, flutter and flare. “Cortisol and adrenaline go up and down,” he said. “Our inflammatory cytokines go up and down.”...The target organs of stress hormones likewise dance to the beat: blood pressure climbs and drops, the heart races and slows, the intestines constrict and relax. This system of so-called allostasis, of maintaining control through constant change, stands in contrast to the mechanisms of homeostasis that keep the pH level and oxygen concentration in the blood within a narrow and invariant range.
Unfortunately, the dynamism of our stress response makes it vulnerable to disruption, especially when the system is treated too roughly and not according to instructions. In most animals, a serious threat provokes a serious activation of the stimulatory, sympathetic, “fight or flight” side of the stress response. But when the danger has passed, the calming parasympathetic circuitry tamps everything back down to baseline flickering...In humans, though, the brain can think too much, extracting phantom threats from every staff meeting or high school dance, and over time the constant hyperactivation of the stress response can unbalance the entire feedback loop. Reactions that are desirable in limited, targeted quantities become hazardous in promiscuous excess. You need a spike in blood pressure if you’re going to run, to speedily deliver oxygen to your muscles. But chronically elevated blood pressure is a source of multiple medical miseries.
Why should the stressed brain be prone to habit formation? Perhaps to help shunt as many behaviors as possible over to automatic pilot, the better to focus on the crisis at hand. Yet habits can become ruts, and as the novelist Ellen Glasgow observed, “The only difference between a rut and a grave are the dimensions.”
Alarm substances are airborne chemical signals, released by an individual into the environment, which communicate emotional stress between conspecifics. Here we tested whether humans, like other mammals, are able to detect emotional stress in others by chemosensory cues. Sweat samples collected from individuals undergoing an acute emotional stressor, with exercise as a control, were pooled and presented to a separate group of participants (blind to condition) during four experiments. In an fMRI experiment and its replication, we showed that scanned participants showed amygdala activation in response to samples obtained from donors undergoing an emotional, but not physical, stressor. An odor-discrimination experiment suggested the effect was primarily due to emotional, and not odor, differences between the two stimuli. A fourth experiment investigated behavioral effects, demonstrating that stress samples sharpened emotion-perception of ambiguous facial stimuli. Together, our findings suggest human chemosensory signaling of emotional stress, with neurobiological and behavioral effects.
Monti et al. examine the proposition that logic inference recruits neural structures traditionally engaged by linguistic processing, and make some very interesting points. Their abstract:
Is human thought fully embedded in language, or do some forms of thought operate independently? To directly address this issue, we focus on inference-making, a central feature of human cognition. In a 3T fMRI study we compare logical inferences relying on sentential connectives (e.g., not, or, if … then) to linguistic inferences based on syntactic transformation of sentences involving ditransitive verbs (e.g., give, say, take). When contrasted with matched grammaticality judgments, logic inference alone recruited “core” regions of deduction [Brodmann area (BA) 10p and 8m], whereas linguistic inference alone recruited perisylvian regions of linguistic competence, among others (BA 21, 22, 37, 39, 44, and 45 and caudate). In addition, the two inferences commonly recruited a set of general “support” areas in frontoparietal cortex (BA 6, 7, 8, 40, and 47). The results indicate that logical inference is not embedded in natural language and confirm the relative modularity of linguistic processes.
Wednesday, August 19, 2009
Nicholas Wade offers one of the best reviews I have seen of work with drugs like resveratrol, which mimic the effect or caloric restriction in animal tests. A companion article by Arnquist notes the proliferation of web sites making unproven health claims and using false celebrity product endorsements for anti-aging and weight-loss pills made from resveratrol. (previous MindBlog postings in this areas can be found by clicking on aging in the topics list in the left column of this web page.) Here are clips from the Wade article which point out reservations about the existing studies:
...the whole phenomenon of caloric restriction may be a misleading result unwittingly produced in laboratory mice. The mice are selected for quick breeding and fed on rich diets. A low-calorie diet could be much closer to the diet that mice are adapted to in the wild, and therefore it could extend life simply because it is much healthier for them...To decide whether life extension by caloric restriction is an artifact of mice in captivity, why not try it on wild mice? Just such an experiment has been done by Steven N. Austad of the University of Texas Health Science Center. Dr. Austad reported that caloric restriction did not extend the average life span of wild mice, suggesting the diet’s benefits are indeed an artifact of mice in captivity. But others interpret his results differently. Richard A. Miller of the University of Michigan, says the maximum life span of the wild mice was extended, and so the experiment was a success for caloric restriction.With reference to the study at Wisconsin on caloric restriction in monkeys:
The monkeys who had spent 20 years on caloric restriction were in better health than their normally fed counterparts, and suffered less diabetes, cancer and heart disease, apparently confirming that caloric restriction holds off the degenerative diseases of aging in primates as well as rodents...But as for life span, the diet extended life significantly only if the researchers excluded deaths that were apparently unrelated to aging, such as under the anesthesia necessary to take blood samples. When all deaths were counted, life span was not significantly extended...Some researchers think it is perfectly valid to ignore such deaths. Others note that in mouse studies one just counts the numbers of dead mice without asking what they died of, and the same procedure should be followed with monkeys, since one cannot be sure if a death under anesthesia might have been age related.Another point:
...last month the results with another substance, the antifungal drug rapamycin, were published (see my July 22 post) Rapamycin was found to extend mice’s lives significantly even though by accident the mice were already the equivalent of 60 years old when the experiment started...Rapamycin has nothing to do with caloric restriction, so far as is known, but the study provided striking proof that a chemical can extend life span.
As a followup on monday's post on happiness and the blogosphere, Benedict Carey points to researchers who suggest that linguistic analysis — of song lyrics, blogs and speeches — could add a new and valuable dimension to a growing area of mass psychology: the determination of national well-being.
From Kovács and Mehler:
Children acquire their native language according to a well-defined time frame. Surprisingly, although children raised in bilingual environments have to learn roughly twice as much about language as their monolingual peers, the speed of acquisition is comparable in monolinguals and bilinguals. Here, we show that preverbal 12-month-old bilingual infants have become more flexible at learning speech structures than monolinguals. When given the opportunity to simultaneously learn two different regularities, bilingual infants learned both, whereas monolinguals learned only one of them. Hence, bilinguals may acquire two languages in the time in which monolinguals acquire one because they quickly become more flexible learners.
Tuesday, August 18, 2009
The research highlights section of the July 29 Nature points out an interesting study from Lihoreau et al. suggesting why, when you find cockroaches in your home, "there's never just one."
Even cockroaches develop psychological problems if they are denied a normal social life. Animals reared in solitude are less likely to explore new environments or search for food, are more timid when approaching other cockroaches and are less able to spot the signs of a good mate. The effects of solitary confinement parallel those of 'isolation syndrome' described in a variety of vertebrates, and the suggestion is that it may develop when any group-living species is denied company.Here is the abstract from the Lihoreau et al study:
Social isolation has dramatic consequences on the development of individuals of many vertebrate species, and it induces a set of behavioural disturbances rending them unable to process environmental as well as social stimuli appropriately. We hypothesized that isolation syndrome is a ubiquitous trait of social life that can be observed in a wide array of species, including invertebrates. Here we report that gregarious cockroaches (Blattella germanica) reared in isolation showed (i) stronger exploration-avoidance, (ii) reduced foraging activity, (iii) reduced willingness to interact socially, and (iv) reduced ability to assess mating partner quality than conspecifics reared in groups. We demonstrate the occurrence of a behavioural syndrome induced by social isolation, similar to syndromes described in vertebrates, revealing the importance of social interactions and group-living in this non-eusocial insect species. We suggest that investigating social isolation effects on individual development should provide interesting results to assess social cohesion of species and thus constitute an additional tool for comparative studies focusing on the evolution of social life.
Greene and Paxton make some interesting observations:
What makes people behave honestly when confronted with opportunities for dishonest gain? Research on the interplay between controlled and automatic processes in decision making suggests 2 hypotheses: According to the “Will” hypothesis, honesty results from the active resistance of temptation, comparable to the controlled cognitive processes that enable the delay of reward. According to the “Grace” hypothesis, honesty results from the absence of temptation, consistent with research emphasizing the determination of behavior by the presence or absence of automatic processes. To test these hypotheses, we examined neural activity in individuals confronted with opportunities for dishonest gain. Subjects undergoing functional magnetic resonance imaging (fMRI) gained money by accurately predicting the outcomes of computerized coin-flips. In some trials, subjects recorded their predictions in advance. In other trials, subjects were rewarded based on self-reported accuracy, allowing them to gain money dishonestly by lying about the accuracy of their predictions. Many subjects behaved dishonestly, as indicated by improbable levels of “accuracy.” Our findings support the Grace hypothesis. Individuals who behaved honestly exhibited no additional control-related activity (or other kind of activity) when choosing to behave honestly, as compared with a control condition in which there was no opportunity for dishonest gain. In contrast, individuals who behaved dishonestly exhibited increased activity in control-related regions of prefrontal cortex, both when choosing to behave dishonestly and on occasions when they refrained from dishonesty. Levels of activity in these regions correlated with the frequency of dishonesty in individuals.
Pronin et al carry out three studies that suggest that knowledge of particular biases in our judgment and inference, and the ability to recognize the impact of those biases on others, neither prevents us from succumbing nor makes us aware of having done so. Indeed, participants in their research denied that their assessments of their personal qualities and their attributions for a particular success or failure had been biased even after having displayed the relevant biases and reading descriptions of them.
Monday, August 17, 2009
Still jet-lagged, I'll be taking some time to cobble myself back together again. Here are a few vacation photos of Deric in London, and Len and Deric in Hagley (Hagley is a far western surburb of Birmingham where we used a colleague's house as a base to explore some spots in the Cotswolds). If I ever needed more personal objective data on the decay of one's brain plasticity on aging, I sure got it when I started to drive on the left after a 14 year absence from the UK! What I recalled as being rather fun and effortless (negotiating complex roundabouts, etc.) now went with much more energy, concentration, focus, and stress. This, I presume, reflects the difference between the 67 year old and the 53 year old versions of Deric's brain.
In the Aug. 3 issue of the New Yorker, Hertzberg writes a concise and lucid description of why we are the only wealthy democracy on this planet that has failed to get either universal health care or some form of guaranteed health insurance. Other democracies can actually make democratic decisions, we appear to be unable to:
A president may fancy that he has a mandate (and, morally, he may well have one), but the two separately elected, differently constituted, independent legilatures whose acquiescence he needs are under no compulsion to agree. Within those legilatures, a system of overlapping committees dominated by powerful chairmen creates a plethora of veto points where well-organized special interest can smother or distort a bill meant to benefit a large but amorphous public. In the smaller of the two legislatures - which is even more heavily weighted toward conservative rural interests than is the larger one, and where one member may represent as little as one-seventieth as many people as the member in the next seat - an arcane and patently unconstitutional rule, the filibuster, allows a minority of members to block almost any action. The process that results is less like the Roman Senate than like the Roman Games: a sanguinary legislative Colosseum where at any moment some two-bit emperor is apt to signal the thumbs-down.
Day in, day out, bloggers pour their feelings onto the Web. Now researchers are mining those outpourings to track society's mood swings.Peter Dodds and Christopher Danforth, applied mathematicians at the University of Vermont, Burlington, automatically searched 2.4 million blogs, via the Web site www.wefeelfine.org, for phrases containing the words "I feel." Their computers then scanned those phrases for 1034 emotionally charged words that a 1999 psychology study had ranked on a happiness scale from 1 (miserable) to 9 (ecstatic). From the words' frequency and scores, an algorithm calculated a net feel-good factor for each day and month.
For the past 4 years, happiness has steadily increased in the blogosphere, Dodds and Danforth reported online recently in the Journal of Happiness Studies. Spirits spike on Christmas and Valentine's Day but dip on 11 September. The happiest day since 2005 was 4 November 2008, the day of the U.S. presidential election. In contrast, Michael Jackson's death in June triggered a 3-day trough.
The Vermont scientists are now studying Twitter feeds. James Fowler, a social scientist at the University of California, San Diego, says the new method will enable scientists "to take the pulse of the whole world, assessing the mood of human society."