Humans alone fluently understand the mental states of others. Humans alone rely on an open-ended system of communication. Humans alone ponder the reasons for their beliefs. For each of these feats, and for others too, humans rely on their most special gift: the ability to represent representations—the ability to form metarepresentations. Hidden behind such mundane thoughts as "Mary believes that Paul believes that it's going to rain" is the explanation of human uniqueness.
There are two ways to represent representations: one immensely powerful, the other rather clumsy. The clumsy way is to create a new representation for every representation that needs to be represented. Using such a device, Mary would have to form a representation "Paul believes that it's going to rain" completely independent of her representation "it's going to rain." She would then have to learn anew all of the inferences that can be drawn from "Paul believe it's going to rain," such as the negative impact on the willingness to go for a jog or the increased probability to fetch an umbrella. This cumbersome process would have to be repeated for each new representation that Mary wishes to attribute, from "Peter things the weather looks lovely" to "Ruth is afraid that the Dow Jones is going to crash tomorrow." Such a process could not possibly account for humans' amazing abilities to attribute just about any thought to other people. How can we account for these skills then?
The explanation is that we use our own representations to attribute thoughts to others. When Mary wants to attribute to Paul the belief "it's going to rain," she 'simply' uses her representation "it's going to rain" and embeds it in a metarepresentation: "Paul thinks "it's going to rain."" Because the same representation is used, Mary can take advantage of the inferences that she could draw from "it's going to rain" to draw inferences from "Paul believes that "it's going to rain."" This trick opened for humans the doors to an unparalleled understanding of their social environment.
Most of the beliefs we form about others are derived from communication: people keep telling us what they believe, want, desire, fear, love… Here again, metarepresentations play a crucial role, since understanding language requires going from utterances—"It's going to rain"—to metarepresentations—"Paul means that "it will soon rain here.""
Mentalizing (attributing thoughts to others) and communicating are the most well known uses of metarepresentations, but they are not the only ones. Metarepresentations are also essential for people to be able to think about reasons. Specific metarepresentations are relied on when people produce and evaluate arguments, as in: "Mary thinks "it's going to rain" is a good argument for "we should not go out."" Again, Mary uses her representation "it's going to rain" but, instead of attributing it to someone else, she represents its strength as a reason to accept a given conclusion.
Several other properties of representations can be represented, from their esthetic value to their normative status. The representational richness made possible by recycling our own representations to represent other people's representations, or to represent other attributes of representations, is our most distinctive trait, one of these amazingly brilliant solutions that natural selection stumbles upon. However, if it is indeed much simpler to rely on this type of metarepresentations than on the cumbersome solution of creating new representations from scratch every time, we still face a complex computational task.
Using the example of mentalizing, it is apparent that even when we use our own representations to attribute representations to other people, a lot of work remains to be done. It cannot be metarepresentations all the way down: at some point, other inputs—linguistic or behavioral cues—have to be used to attribute representations. Moreover, when a representation is represented not all of the inferences that can be drawn from it are relevant. When Mary believes that John believes it's going to rain, some of the inferences that she would draw from "it's going to rain" may not be attributable to John—maybe he doesn't mind jogging in the rain for instance. Other inferences Mary may not spontaneously draw—maybe John will be worried because he has left his book outside. Still, without a baseline—Mary's own representation—the task would jump from merely difficult to utterly intractable.
Probably more than any other cognitive trait, the ability to use our own representations to represent representations is what explains humans' achievements. Without this skill, the complex forms of social cognition that characterize our species would have been all but impossible. It is also critical for us psychologists to understand these ideas if we want to continue our forays into human cognition.
I leave the last word to Dan Sperber who, more than any other cognitive scientists, has made of metarepresentations the most central explanation of humans' unique cognition: "Humans have the ability to represent representations. I would argue that this meta-representational ability is as distinctive of humans, and as important in understanding their behaviour, as is echolocation for bats."
This blog reports new ideas and work on mind, brain, behavior, psychology, and politics - as well as random curious stuff. (Try the Dynamic Views at top of right column.)
Friday, July 06, 2012
Metarepresentations explain human uniqueness.
I pass along this essay by Hugo Mercier:
Thursday, July 05, 2012
Mechanisms of white matter changes induced by meditation.
Diffusion tensor imaging (DTI) is a noninvasive MRI-based technique that can delineate white matter fibers in vivo, measure white matter’s structural plasticity to demonstrate that training or learning alters brain white matter. Fractional anisotropy (FA) is an important index for measuring the integrity of white matter fibers. In general, a higher FA value has been related to improved performance, and reduced FA has been found in normal aging and in neurological or psychiatric disorders. Posner and collaborators now show more details about changes that occur with only 4 weeks of meditation training (One suspects these changes might reverse after cessation of meditation practice?):
Using diffusion tensor imaging, several recent studies have shown that training results in changes in white matter efficiency as measured by fractional anisotropy (FA). In our work, we found that a form of mindfulness meditation, integrative body–mind training (IBMT), improved FA in areas surrounding the anterior cingulate cortex after 4-wk training more than controls given relaxation training. Reductions in radial diffusivity (RD) have been interpreted as improved myelin but reductions in axial diffusivity (AD) involve other mechanisms, such as axonal density. We now report that after 4-wk training with IBMT, both RD and AD decrease accompanied by increased FA, indicating improved efficiency of white matter involves increased myelin as well as other axonal changes. However, 2-wk IBMT reduced AD, but not RD or FA, and improved moods. Our results demonstrate the time-course of white matter neuroplasticity in short-term meditation. This dynamic pattern of white matter change involving the anterior cingulate cortex, a part of the brain network related to self-regulation, could provide a means for intervention to improve or prevent mental disorders.Here is their description of the integrative body-mind training (IBMT) used:
IBMT involves body relaxation, mental imagery, and mindfulness training, accompanied by selected music background. Cooperation between the body and the mind is emphasized in facilitating and achieving a meditative state. The trainees concentrated on achieving a balanced state of body and mind guided by an IBMT coach and the compact disk. The method stresses no effort to control thoughts, but instead a state of restful alertness that allows a high degree of awareness of body, mind, and external instructions (5, 16, 19). RT involves the relaxing of different muscle groups over the face, head, shoulders, arms, legs, chest, back, and abdomen, guided by a tutor and compact disk. With eyes closed and in a sequential pattern, one is forced to concentrate on the sensation of relaxation, such as the feelings of warmth and heaviness. This progressive training helps the participant achieve physical and mental relaxation and calmness.
Wednesday, July 04, 2012
Hierarchy increases group effectiveness.
From Ronay et al.:
Two experiments examined the psychological and biological antecedents of hierarchical differentiation and the resulting consequences for productivity and conflict within small groups. In Experiment 1, which used a priming manipulation, hierarchically differentiated groups (i.e., groups comprising 1 high-power-primed, 1 low-power-primed, and 1 baseline individual) performed better on a procedurally interdependent task than did groups comprising exclusively either all high-power-primed or all low-power-primed individuals. There were no effects of hierarchical differentiation on performance on a procedurally independent task. Experiment 2 used a biological marker of dominance motivation (prenatal testosterone exposure as measured by a digit-length ratio) to manipulate hierarchical differentiation. The pattern of results from Experiment 1 was replicated; mixed-testosterone groups achieved greater productivity than did groups comprising all high-testosterone or all low-testosterone individuals. Furthermore, intragroup conflict mediated the productivity decrements for the high-testosterone but not the low-testosterone groups. This research suggests possible directions for future research and the need to further delineate the conditions and types of hierarchy under which hierarchical differentiation enhances rather than undermines group effectiveness.
Tuesday, July 03, 2012
Connectivity of prefrontal cortex predicts cognitive control and intelligence
From Cole et al.:
Control of thought and behavior is fundamental to human intelligence. Evidence suggests a frontoparietal brain network implements such cognitive control across diverse contexts. We identify a mechanism—global connectivity—by which components of this network might coordinate control of other networks. A lateral prefrontal cortex (LPFC) region's activity was found to predict performance in a high control demand working memory task and also to exhibit high global connectivity. Critically, global connectivity in this LPFC region, involving connections both within and outside the frontoparietal network, showed a highly selective relationship with individual differences in fluid intelligence. These findings suggest LPFC is a global hub with a brainwide influence that facilitates the ability to implement control processes central to human intelligence.
Figure - Cognitive control regions, as defined by successful cognitive control. A, Regions of Interest (ROIs) were defined based on brain activity during successful N-back task performance. The following highly selective criteria were used: preferential activation for trials requiring flexible control (lures), correct > incorrect trials, positive correlation with accuracy across participants. All 3 of these regions were hubs (in top 10% connectivity in the brain).
Monday, July 02, 2012
Hygiene can hurt.
I pass on this summary from the Editor's choice section of Science, follwed by the abstract of the work mentioned. It describes further work on how failure to interact with natural environments during childhood can lead to later chronic inflammatory disorders. Also, relevant to this topic is a recent Op-Ed piece in the NYTimes called "Dirtying Up Our Diets.", and this further piece discusses our human microbiome.
As human societies urbanize, chronic inflammatory disorders become more apparent. The hygiene hypothesis suggests that individuals exposed to infection in childhood are less likely to develop inflammatory disease because exposure to microorganisms is important for stimulating responses that maintain epithelial cell integrity. Hence, in urban environments, reduced contact with the full diversity of the microbial world may be leading to the increased incidence of inflammatory disorders. Hanski et al. took a random sample of 118 adolescents from towns, villages, and isolated dwellings in eastern Finland, tested their immune function and allergic responses, surveyed their skin microflora, and investigated the biodiversity within their homes. They found several significant correlations, not least that low biodiversity was surprisingly strongly associated with atopy, and concluded that humans need to interact with natural environments for their physical health, not just for their peace of mind.Here is the Hanski et al. abstract:
Rapidly declining biodiversity may be a contributing factor to another global megatrend—the rapidly increasing prevalence of allergies and other chronic inflammatory diseases among urban populations worldwide. According to the “biodiversity hypothesis,” reduced contact of people with natural environmental features and biodiversity may adversely affect the human commensal microbiota and its immunomodulatory capacity. Analyzing atopic sensitization (i.e., allergic disposition) in a random sample of adolescents living in a heterogeneous region of 100 × 150 km, we show that environmental biodiversity in the surroundings of the study subjects’ homes influenced the composition of the bacterial classes on their skin. Compared with healthy individuals, atopic individuals had lower environmental biodiversity in the surroundings of their homes and significantly lower generic diversity of gammaproteobacteria on their skin. The functional role of the Gram-negative gammaproteobacteria is supported by in vitro measurements of expression of IL-10, a key anti-inflammatory cytokine in immunologic tolerance, in peripheral blood mononuclear cells. In healthy, but not in atopic, individuals, IL-10 expression was positively correlated with the abundance of the gammaproteobacterial genus Acinetobacter on the skin. These results raise fundamental questions about the consequences of biodiversity loss for both allergic conditions and public health in general.
Friday, June 29, 2012
Life satisfaction and economic growth.
Richard Easterlin coauthored a seminal study in 1974 that attempted to explain why the happiness score in the United Sates and elsewhere had stayed constant while per capita income had gone up. His explanation was that economic growth has a positive effect on happiness with other things being equal; however, it also raises aspirations, and aspirations have a negative effect. Aspirations are determined by society, particularly reference group income. The combination of these two effects gives rise to a Hedonic Treadmill.
He now has coauthored a study on China, an excellent setting for investigating the relationship between economic growth and life satisfaction. Over the period of economic reform, starting in 1978, income per capita rose 10-fold, China’s Human Development Index score improved impressively in all three dimensions, and through its steady, evolutionary reforms, China avoided the hardship that would have accompanied an economic revolution. Surely the Chinese people became happier as a result?
On the contrary, his latest results bear some erie similarities to the unequal effects of our current economic downturn on low versus higher income citizens:
Despite its unprecedented growth in output per capita in the last two decades, China has essentially followed the life satisfaction trajectory of the central and eastern European transition countries—a U-shaped swing and a nil or declining trend. There is no evidence of an increase in life satisfaction of the magnitude that might have been expected to result from the fourfold improvement in the level of per capita consumption that has occurred. As in the European countries, in China the trend and U-shaped pattern appear to be related to a pronounced rise in unemployment followed by a mild decline, and an accompanying dissolution of the social safety net along with growing income inequality. The burden of worsening life satisfaction in China has fallen chiefly on the lowest socioeconomic groups. An initially highly egalitarian distribution of life satisfaction has been replaced by an increasingly unequal one, with decreasing life satisfaction in persons in the bottom third of the income distribution and increasing life satisfaction in those in the top third.
Thursday, June 28, 2012
Synchronized brain activity across individuals during emotional arousal.
From Nummenmaa et al.:
Sharing others’ emotional states may facilitate understanding their intentions and actions. Here we show that networks of brain areas “tick together” in participants who are viewing similar emotional events in a movie. Participants’ brain activity was measured with functional MRI while they watched movies depicting unpleasant, neutral, and pleasant emotions. After scanning, participants watched the movies again and continuously rated their experience of pleasantness–unpleasantness (i.e., valence) and of arousal–calmness. Pearson’s correlation coefficient was used to derive multisubject voxelwise similarity measures [intersubject correlations (ISCs)] of functional MRI data. Valence and arousal time series were used to predict the moment-to-moment ISCs computed using a 17-s moving average. During movie viewing, participants' brain activity was synchronized in lower- and higher-order sensory areas and in corticolimbic emotion circuits. Negative valence was associated with increased ISC in the emotion-processing network (thalamus, ventral striatum, insula) and in the default-mode network (precuneus, temporoparietal junction, medial prefrontal cortex, posterior superior temporal sulcus). High arousal was associated with increased ISC in the somatosensory cortices and visual and dorsal attention networks comprising the visual cortex, bilateral intraparietal sulci, and frontal eye fields. Seed-voxel–based correlation analysis confirmed that these sets of regions constitute dissociable, functional networks. We propose that negative valence synchronizes individuals’ brain areas supporting emotional sensations and understanding of another’s actions, whereas high arousal directs individuals’ attention to similar features of the environment. By enhancing the synchrony of brain activity across individuals, emotions may promote social interaction and facilitate interpersonal understanding.
Wednesday, June 27, 2012
Cumulative life stress decreases working memory and prefrontal cortex size.
Two of my colleagues here at the University of Wisconsin, Richard Davidson and Seth Pollack, have collaborated with others in a sobering study that demonstrates brain changes caused by childhood stress:
A large corpus of research indicates that exposure to stress impairs cognitive abilities, specifically executive functioning dependent on the prefrontal cortex (PFC). We collected structural MRI scans (n = 61), well-validated assessments of executive functioning, and detailed interviews assessing stress exposure in humans to examine whether cumulative life stress affected brain morphometry and one type of executive functioning, spatial working memory, during adolescence—a critical time of brain development and reorganization. Analysis of variations in brain structure revealed that cumulative life stress and spatial working memory were related to smaller volumes in the PFC, specifically prefrontal gray and white matter between the anterior cingulate and the frontal poles. Mediation analyses revealed that individual differences in prefrontal volumes accounted for the association between cumulative life stress and spatial working memory. These results suggest that structural changes in the PFC may serve as a mediating mechanism through which greater cumulative life stress engenders decrements in cognitive functioning.A study in the same vein on rhesus monkeys also notes late life heath effects of early adversity:
This paper exploits a unique ongoing experiment to analyze the effects of early rearing conditions on physical and mental health in a sample of rhesus monkeys (Macaca mulatta). We analyze the health records of 231 monkeys that were randomly allocated at birth across three rearing conditions: mother rearing, peer rearing, and surrogate peer rearing. We show that the lack of a secure attachment relationship in the early years engendered by adverse rearing conditions has detrimental long-term effects on health that are not compensated for by a normal social environment later in life.
Blog Categories:
fear/anxiety/stress,
human development
Tuesday, June 26, 2012
Finding genes that affect brain integrity and intellectual performance
Chiang et al. have looked at brain images of 472 twins and their non-twin siblings to observe gene network effects on brain microstructure and intellectual performance:
A major challenge in neuroscience is finding which genes affect brain integrity, connectivity, and intellectual function. Discovering influential genes holds vast promise for neuroscience, but typical genome-wide searches assess approximately one million genetic variants one-by-one, leading to intractable false positive rates, even with vast samples of subjects. Even more intractable is the question of which genes interact and how they work together to affect brain connectivity. Here, we report a novel approach that discovers which genes contribute to brain wiring and fiber integrity at all pairs of points in a brain scan. We studied genetic correlations between thousands of points in human brain images from 472 twins and their nontwin siblings (mean age: 23.7 ± 2.1 SD years; 193 male/279 female). We combined clustering with genome-wide scanning to find brain systems with common genetic determination. We then filtered the image in a new way to boost power to find causal genes. Using network analysis, we found a network of genes that affect brain wiring in healthy young adults. Our new strategy makes it computationally more tractable to discover genes that affect brain integrity. The gene network showed small-world and scale-free topologies, suggesting efficiency in genetic interactions and resilience to network disruption. Genetic variants at hubs of the network influence intellectual performance by modulating associations between performance intelligence quotient and the integrity of major white matter tracts, such as the callosal genu and splenium, cingulum, optic radiations, and the superior longitudinal fasciculus.
Monday, June 25, 2012
Happiness for people who can’t stand positive thinking.
Being a bit curmudgeonly about the whole Happiness industry, and having once been a contrarian guest on a west coast happiness radio program (whose message was to laugh and be positive ALL the time), I thought I should mention a nice book “The Antidote”, by Oliver Burkeman, on embracing uncertainty and rediscovering the power of negative thinking. He offers this animated trailer:
Friday, June 22, 2012
How depressives surf the web.
A brief piece with the title of this post recently appeared in the NYTimes, and is an example of annoying phenomenon: advertising by advance announcement in popular media with reference made to a "forthcoming" article. The points raised are interesting enough that the reader deserves access to what might be more thorough analysis and discussion. I'm thinking the correlations indicated might be quite spurious. For what it is worth, in a study involving the usual gaggle of undergraduate volunteers, the authors claim to have:
...identified several features of Internet usage that correlated with depression. In other words, we found a trend: in general, the more a participant’s score on the survey indicated depression, the more his or her Internet usage included these (rather technical-sounding) features — for instance, “p2p packets,” which indicate high levels of sharing files (like movies and music).
Our second major discovery was that there were patterns of Internet usage that were statistically high among participants with depressive symptoms compared with those without symptoms. That is, we found indicators: styles of Internet behavior that were signs of depressive people. For example, participants with depressive symptoms tended to engage in very high e-mail usage. This perhaps was to be expected: research by the psychologists Janet Morahan-Martin and Phyllis Schumacher has shown that frequent checking of e-mail may relate to high levels of anxiety, which itself correlates with depressive symptoms.
Another example: the Internet usage of depressive people tended to exhibit high “flow duration entropy” — which often occurs when there is frequent switching among Internet applications like e-mail, chat rooms and games. This may indicate difficulty concentrating. This finding, too, is consistent with the psychological literature: according to the National Institute of Mental Health, difficulty concentrating is also a sign of depressive symptoms among students... OTHER characteristic features of “depressive” Internet behavior included increased amounts of video watching, gaming and chatting.
Blog Categories:
culture/politics,
emotion,
technology
Thursday, June 21, 2012
Highjacked brain fallacy, and free will illusion going mainstream.
In a series of previous posts on MindBlog I have enjoyed following the continuing back and forth over free will and neuroscience,and my own sentiments are clearly revealed in my introductory web/lecture listed in the column to your left ("The I Illusion"). A raft of books on this subject has recently appeared, an example being Eagleman's "Incognito: Secret Lives of the Brain" as well as several mentioned in a recent Huffington Post essay by Victor Strenger. An interesting variation on the free will question is provided by O'Connor's discussion of a popular analogy that clouds our discussion of addiction, i.e. the portrayal of addition as a disease (not subject to our willful control, thus not the responsibility of the victim) rather than a choice.
In the “hijacked” view of addiction, the brain is the innocent victim of certain substances — alcohol, cocaine, nicotine or heroin, for example — as well as certain behaviors like eating, gambling or sexual activity...drugs like alcohol and cocaine and behaviors like gambling light up the brain’s pleasure circuitry, often bringing a burst of euphoria. Other studies indicate that people who are addicted have lower dopamine and serotonin levels in their brains, which means that it takes more of a particular substance or behavior for them to experience pleasure or to reach a certain threshold of pleasure.However,
"A hijacker comes from outside and takes control by violent means. A hijacker takes a vehicle that is not his; hijacking is always a form of stealing and kidnapping...The analogy of addiction and hijacking involves the same category mistake as the money switched from hand to hand...It might be tempting to claim that in an addiction scenario, the drugs or behaviors are the hijackers. However, those drugs and behaviors need to be done by the person herself...In the usual cases, an individual is the one putting chemicals into her body or engaging in certain behaviors in the hopes of getting high...There is a kind of intentionality to hijacking that clearly is absent in addiction...Addiction develops over time and requires repeated and worsening use...If we think, however, of addiction as involving both choice and disease, our outlook is likely to become more nuanced.
Linking choice and responsibility is right in many ways, so long as we acknowledge that choice can be constrained in ways other than by force or overt coercion. There is no doubt that the choices of people progressing to addiction are constrained; compulsion and impulsiveness constrain choices. Many addicts will say that they choose to take that first drink or drug and that once they start they cannot stop. A classic binge drinker is a prime example; his choices are constrained with the first drink. He both has and does not have a choice. (That moment before the first drink or drug is what the philosopher Owen Flanagan describes as a “zone of control.”) But he still bears some degree of responsibility to others and to himself...Addicts are neither hijackers nor victims. It is time to retire this analogy.
Wednesday, June 20, 2012
Exercise bad for you?
My almost religious devotion to exercise has been slightly nudged by this piece by Gina Kolata pointing to a study by Bouchard et al., who do a rather thorough exercise study involving 1,687 people to find that
...about 10 percent actually got worse on at least one of the measures related to heart disease: blood pressure and levels of insulin, HDL cholesterol or triglycerides....But counterbalancing the 10 percent who got worse were about the same proportion who had an exaggeratedly good response on at least one measure. Others had responses ranging from little or no change up to big changes, seen in about 10 percent, where risk factor measurements improved anywhere from 20 percent to 50 percent.
Tuesday, June 19, 2012
The burdens of being a biped
Given my current preoccupation with my failing 70 year old knee joints, I was drawn to a brief piece by Elizabeth Pennisi with the title of this post. Here I give a summary graphic and a few clips of her discussion:
...a number of musculoskeletal issues are traceable to our past, in particular to the switch to walking upright more than 7 million years ago…Shifting from a four-legged support system to a two-legged one put extra stress on the legs and vertebrae. Adaptations in the feet, knees, hips, pelvis, and spine accommodate these forces, but at a cost…vertebrae that break more easily, weaker bones, and feet prone to heel spurs and sprained ankles…A brief tour of the body reveals a number of design flaws, the legacy of our past…
Spine. Back pain is the leading health complaint in the United States. In dogs, horses, and even chimpanzees, the backbone is a series of vertebrae neatly stacked and evenly spaced to form a relatively stiff, gently curving beam…the human spine… is highly flexible and can even bend backward..this flexibility creates wear and tear on joint surfaces and predisposes us to osteoarthritis…One type of break, called spondylolysis, affects about 6% of the U.S. population and is a leading cause of lower-back pain in teenage athletes. In this condition, the neural arch - a triangle of bone that surrounds the spinal cord - detaches from the rest of its vertebra, allowing the spine to slip forward relative to the back of the pelvis, pinching nerves and causing pain…the problem lies in inadequate spacing between the joints connecting the vertebrae.
Feet. To cope with the added load on just two feet, the foot evolved a shock-absorbing arch by bringing what was a grasping big toe into line with the other toes. When that arch fails to form fully, as in people with flat feet, fatigue fractures can result.
Fragile bones. The added load on two feet also caused knee and hip joints to expand, creating more surface area to absorb foot-fall forces. But the joints—and vertebrae as well—evolved to be bigger by enlarging the spongy, inner bone and thinning the hard, outer bone. As a result, human bones are less dense than those of other primates. Bone...loses mass during adulthood. With humans having ever longer life spans, bones, particularly vertebrae, may become fragile and break spontaneously.
Bipedality leaves its mark in other parts of our bodies, too, for example in the difficulty of childbirth and in our vulnerability to rotator cuff injuries of the shoulder. loses mass during adulthood. With humans having ever longer life spans, bones, particularly vertebrae, may become fragile and break spontaneously.
...a number of musculoskeletal issues are traceable to our past, in particular to the switch to walking upright more than 7 million years ago…Shifting from a four-legged support system to a two-legged one put extra stress on the legs and vertebrae. Adaptations in the feet, knees, hips, pelvis, and spine accommodate these forces, but at a cost…vertebrae that break more easily, weaker bones, and feet prone to heel spurs and sprained ankles…A brief tour of the body reveals a number of design flaws, the legacy of our past…
Spine. Back pain is the leading health complaint in the United States. In dogs, horses, and even chimpanzees, the backbone is a series of vertebrae neatly stacked and evenly spaced to form a relatively stiff, gently curving beam…the human spine… is highly flexible and can even bend backward..this flexibility creates wear and tear on joint surfaces and predisposes us to osteoarthritis…One type of break, called spondylolysis, affects about 6% of the U.S. population and is a leading cause of lower-back pain in teenage athletes. In this condition, the neural arch - a triangle of bone that surrounds the spinal cord - detaches from the rest of its vertebra, allowing the spine to slip forward relative to the back of the pelvis, pinching nerves and causing pain…the problem lies in inadequate spacing between the joints connecting the vertebrae.
Feet. To cope with the added load on just two feet, the foot evolved a shock-absorbing arch by bringing what was a grasping big toe into line with the other toes. When that arch fails to form fully, as in people with flat feet, fatigue fractures can result.
Fragile bones. The added load on two feet also caused knee and hip joints to expand, creating more surface area to absorb foot-fall forces. But the joints—and vertebrae as well—evolved to be bigger by enlarging the spongy, inner bone and thinning the hard, outer bone. As a result, human bones are less dense than those of other primates. Bone...loses mass during adulthood. With humans having ever longer life spans, bones, particularly vertebrae, may become fragile and break spontaneously.
Bipedality leaves its mark in other parts of our bodies, too, for example in the difficulty of childbirth and in our vulnerability to rotator cuff injuries of the shoulder. loses mass during adulthood. With humans having ever longer life spans, bones, particularly vertebrae, may become fragile and break spontaneously.
Monday, June 18, 2012
A musical offering.
As has been my custom, I post on this blog piano video-recordings that I have recently made, this being the Chopin Nocturne in C# Minor that I played at a house concert on May 27, and subsequently recorded on June 10.
Friday, June 15, 2012
Skin Pics
One frequently comes across amazing images in cell biology. This time I felt like passing some on to readers.
Thursday, June 14, 2012
The science of gaydar
Yet another study suggesting that we have an ability (if not a proficiency) to correctly judge the sexual orientation of others about 60% of the time, significantly great than chance. This piece in the New York Times points to work by Tabak and Zayas:
Research has shown that people are able to judge sexual orientation from faces with above-chance accuracy, but little is known about how these judgments are formed. Here, we investigated the importance of well-established face processing mechanisms in such judgments: featural processing (e.g., an eye) and configural processing (e.g., spatial distance between eyes). Participants judged sexual orientation from faces presented for 50 milliseconds either upright, which recruits both configural and featural processing, or upside-down, when configural processing is strongly impaired and featural processing remains relatively intact. Although participants judged women’s and men’s sexual orientation with above-chance accuracy for upright faces and for upside-down faces, accuracy for upside-down faces was significantly reduced. The reduced judgment accuracy for upside-down faces indicates that configural face processing significantly contributes to accurate snap judgments of sexual orientation.
Wednesday, June 13, 2012
Brain correlates of resting, alert, and meditation states.
Posner and colleagues do a nice review of neural correlates of establishing, maintaining, and switching brain states. I thought I would pass on a few chunks from their article describing the alert state and the meditation state:
The three brain states are compared in Table 1.
The meditation state differs from the alert state induced by a warning signal in several crucial ways. First, the alert state can be induced by the simple instruction to expect a target, without requiring any practice, whereas the meditation state requires specific instruction and practice. Second, the alert state requires an external target, whereas the meditation state may not involve a target event. Third, the alert state involves primarily the neuromodulator NE, whereas dopamine (DA) has often been shown to be important to the meditation state. Finally, the alert state involves a reduction in ACC activity, likely in order to keep the mind clear to perceive and respond quickly to the target. The meditation state, however, shows increased ACC activity that serves to regulate mind wandering. As mentioned previously, Five days of integrative mind-body training (IBMT) increases brain activity in the ACC, insula, and striatum. One month of IBMT improves white matter connectivity between the ACC, striatum, and other regions. Based on these results and related work, we propose the insula, ACC, and stiatum (IAS) as key neural correlates of changing brain states (Figure 2).
Because of its role in attention and self-regulation, we hypothesize that the ACC is involved in maintaining a state by reducing conflict with other states; the insula serves a primary role in switching between states, and the striatum is linked to the reward experience and formation of habits needed to make maintenance easier. The insula and ACC work together to support the role of the autonomic nervous system in maintaining the meditation state.
Tuesday, June 12, 2012
Your great grandparent's experience might have altered your stress response.
This fascinating nugget from Crews et a. (open access) adds to accumulating evidence on the importance of experience induced modification of our genomes that can be passed between generations. (The experiments are on mice, because obviously you don't do this kind of study directly on humans.)
Ancestral environmental exposures have previously been shown to promote epigenetic transgenerational inheritance and influence all aspects of an individual’s life history. In addition, proximate life events such as chronic stress have documented effects on the development of physiological, neural, and behavioral phenotypes in adulthood. We used a systems biology approach to investigate in male rats the interaction of the ancestral modifications carried transgenerationally in the germ line and the proximate modifications involving chronic restraint stress during adolescence. We find that a single exposure to a common-use fungicide (vinclozolin) three generations removed alters the physiology, behavior, metabolic activity, and transcriptome in discrete brain nuclei in descendant males, causing them to respond differently to chronic restraint stress. This alteration of baseline brain development promotes a change in neural genomic activity that correlates with changes in physiology and behavior, revealing the interaction of genetics, environment, and epigenetic transgenerational inheritance in the shaping of the adult phenotype. This is an important demonstration in an animal that ancestral exposure to an environmental compound modifies how descendants of these progenitor individuals perceive and respond to a stress challenge experienced during their own life history.
Blog Categories:
genes,
human development,
human evolution
Monday, June 11, 2012
MindBlog's other lives
This post is sharing with readers two aspects of Deric's private life. I studied visual transduction over a 36 year period (1960-1996), and on Saturday May 26, near a 70th birthday in May, my former students gathered in Madison Wisconsin (one flying from Japan for the weekend!) for a laboratory reunion. Several former Ph.D. or postdoctoral students now head their own laboratories, are department chairs, have chair professorships, or have won academic prizes. In preparation for the reunion, I prepared a brief web history of the laboratory, and pictures of the reunion can be found here.
On the next day, Sunday May 27, my partner Len (on right in the picture below) and I hosted a Social/Musical at our Twin Valley home (an 1860 stone schoolhouse converted to a residence) that was attended by friends as well as many who were at the laboratory reunion. Music selections were from the romantic literature, by Chopin, Brahms, Faure, and Debussy. Pictures of that occasion can be found here. Included in this post is a video of the Chopin C Minor Nocture played at the Social, recorded this past Saturday. I hope to do video recordings of several of the pieces played in the next period of time.)
On the next day, Sunday May 27, my partner Len (on right in the picture below) and I hosted a Social/Musical at our Twin Valley home (an 1860 stone schoolhouse converted to a residence) that was attended by friends as well as many who were at the laboratory reunion. Music selections were from the romantic literature, by Chopin, Brahms, Faure, and Debussy. Pictures of that occasion can be found here. Included in this post is a video of the Chopin C Minor Nocture played at the Social, recorded this past Saturday. I hope to do video recordings of several of the pieces played in the next period of time.)
Subscribe to:
Posts (Atom)