More on building brains with video games

Nick Bilton does a brief piece on how trying to win various kinds of video games enhances subsequent performance on real world attention and memory tests.

Daphné Bavelier, a neuroscientist with the University of Rochester, found that people who play first-person shooter video games for two weeks can improve visual attention, mental reasoning and decision-making skills. A 2007 study by Iowa State University psychologists compared surgeons who played video games to those who didn’t and found that, during laparoscopic surgeries, the gamers were 27 percent faster and made 37 percent fewer mistakes than nongamers. And decades of research around Tetris has shown that playing it for extended periods may increase memory and cognitive skills.

....the goal is to figure out what makes a game addictive on a neurological level, then to couple this with brain research showing how play can improve the mind...imagine five years from now that you go to the doctor with a problem and he prescribes an F.D.A.-approved video game for you to download and play for two weeks.

Want to remember something? Have some coffee!

Here is the brief abstract from Borota et al., followed by a graphic summary of the results offered by Favila and Kuhl:

It is currently not known whether caffeine has an enhancing effect on long-term memory in humans. We used post-study caffeine administration to test its effect on memory consolidation using a behavioral discrimination task. Caffeine enhanced performance 24 h after administration according to an inverted U-shaped dose-response curve; this effect was specific to consolidation and not retrieval. We conclude that caffeine enhanced consolidation of long-term memories in humans.

Figure: Effect of post-encoding caffeine on memory. On day 1, subjects viewed a series of images of everyday objects and made a judgment about whether each image was likely to be found indoors or outdoors. Immediately after completing this task, they took either caffeine or placebo. Measured caffeine levels fully returned to baseline by the next day. On day 2, subjects were given a surprise memory test. Subjects viewed a series of images and decided whether each image was new (not seen on day 1), old (identical to one of the images from day 1) or similar (a different exemplar of one of the images seen on day 1). The probability of correctly labeling similar images as similar (instead of old) was reflected by a lure discrimination index that corrected for potential response bias. Subjects who received 200 or 300 mg of caffeine after the study period on day 1 showed enhanced lure discrimination on day 2 compared with subjects who received placebo. At 100 mg, caffeine did not enhance test performance, nor did caffeine administered just before the memory test (not shown).

Cognitive aging - a dark side to environmental support?

Lindenberger and Mayr make some very interesting points on the consequences of shifting during aging from self initiation to environmental support in performing tasks. This hits me right between the eyes, as I have been noticing lately how much more likely I am to be working on tasks that are generated by, or reactive to, to my immediate physical, social, financial environment than on projects (like generating music and writing) that I initiate and stay focused on. The Lindenberger and Mayr paper (available to motivated readers who email me) reviews a number of studies beyond the original work on memory by Craik, studies that generalize the effects of self initiated versus environmental support to other cognitive areas such as visual and auditory control. Across processing stages and modalities, older adults are more likely to be guided by external cues than younger adults are. Here I pass on summary points, abstract, and a clip from the discussion.

• Perceptual salience rather than attentional focus governs stimulus processing in old age.
• Older adults rely more on environmental prompts for action than younger adults do.
• Environmental support helps older adults to perform but results in loss of internal control.
• The structure of the environment matters, especially for older adults.

It has been known for some time that memory deficits among older adults increase when self-initiated processing is required and decrease when the environment provides task-appropriate cues. We propose that this observation is not confined to memory but can be subsumed under a more general developmental trend. In perception, learning or memory, and action management, older adults often rely more on external information than younger adults do, probably both as a direct reflection and indirect adaptation to difficulties in internally triggering and maintaining cognitive representations. This age-graded shift from internal towards environmental control is often associated with compromised performance. Cognitive aging research and the design of aging-friendly environments can benefit from paying closer attention to the developmental dynamics and implications of this shift.

Environmental support has a bright and a dark side: it helps aging individuals to perform but comes with a loss in internal control. It follows that the environment matters, especially in old age. The initiation and maintenance of internal control are costly, both cognitively and metabolically and these costs appear to increase from early to late adulthood. By the time they have reached old age, individuals have acquired a behavioral repertoire that is likely to match the regularities and affordances of the environments they live in. The tendency of older adults, both automatic and deliberate, to outsource control to the environment may be inefficient at times, but cost-effective in the long run if the cuing structure of the environment corresponds to their goals and needs. Engineers, psychologists, and aging individuals themselves need to keep this in mind as they design and use adaptive technology in the pursuit of successful aging.

A brain basis for musical hallucinations

Kumar et al. report their findings from an unusual opportunity that presented itself when a retired London schoolteacher, Sylvia, reported to her doctors that she increasingly was hearing music, as if it were completely real, in the absence of a source for the music. (People with musical hallucinations usually are psychologically normal — except for the music they are sure someone is playing. ) Sylvia volunteered for a study by Kumar et al. that made use of the fact that real music can sometimes quiet the imaginary music, in effect masking music hallucination. Playing Bach for 30 seconds was used to damp down the hallucinations while the teacher's brain activity was being monitored by MEG (magnetic recordings), and when the real music stopped the teacher reported the strength of hallucinations as they returned. The brain regions becoming more active as hallucinations returned were the same as those activated by listening to real music. From Zimmer’s review of this work, a suggested model for what is happening:

Our brains… generate predictions about what is going to happen next, using past experiences as a guide. When we hear a sound, for example — particularly music — our brains guess at what it is and predict what it will sound like in the next instant. If the prediction is wrong — if we mistook a teakettle for an opera singer — our brains quickly recognize that we are hearing something else and make a new prediction to minimize the error….people with musical hallucinations often have at least some hearing loss. Sylvia, for example, needed hearing aids after getting a viral infection two decades ago.

The model of our brain as a prediction-generating machine

...could explain why some people with hearing loss develop musical hallucinations. With fewer auditory signals entering the brain, their error detection becomes weaker. If the music-processing brain regions make faulty predictions, those predictions only grow stronger until they feel like reality.

This model:

...could explain why real music provides temporary relief for musical hallucinations: the incoming sounds reveal the brain’s prediction errors. And it may also explain why people are prone to hallucinate music, and not other familiar sounds.

Here is the Kumar et al. abstract:

The physiological basis for musical hallucinations (MH) is not understood. One obstacle to understanding has been the lack of a method to manipulate the intensity of hallucination during the course of experiment. Residual inhibition, transient suppression of a phantom percept after the offset of a masking stimulus, has been used in the study of tinnitus. We report here a human subject whose MH were residually inhibited by short periods of music. Magnetoencephalography (MEG) allowed us to examine variation in the underlying oscillatory brain activity in different states. Source-space analysis capable of single-subject inference defined left-lateralised power increases, associated with stronger hallucinations, in the gamma band in left anterior superior temporal gyrus, and in the beta band in motor cortex and posteromedial cortex. The data indicate that these areas form a crucial network in the generation of MH, and are consistent with a model in which MH are generated by persistent reciprocal communication in a predictive coding hierarchy.

The right temperature for a stroking caress

We apparently have sensory nerves in our skin that are exquisitely tuned for human hedonic, affiliative contact. From Ackerley et al.:

Human C-tactile (CT) afferents respond vigorously to gentle skin stroking and have gained attention for their importance in social touch. Pharmacogenetic activation of the mouse CT equivalent has positively reinforcing, anxiolytic effects, suggesting a role in grooming and affiliative behavior. We recorded from single CT axons in human participants, using the technique of microneurography, and stimulated a unit's receptive field using a novel, computer-controlled moving probe, which stroked the skin of the forearm over five velocities (0.3, 1, 3, 10, and 30 cm s−1) at three temperatures (cool, 18°C; neutral, 32°C; warm, 42°C). We show that CTs are unique among mechanoreceptive afferents: they discharged preferentially to slowly moving stimuli at a neutral (typical skin) temperature, rather than at the cooler or warmer stimulus temperatures. In contrast, myelinated hair mechanoreceptive afferents proportionally increased their firing frequency with stroking velocity and showed no temperature modulation. Furthermore, the CT firing frequency correlated with hedonic ratings to the same mechano-thermal stimulus only at the neutral stimulus temperature, where the stimuli were felt as pleasant at higher firing rates. We conclude that CT afferents are tuned to respond to tactile stimuli with the specific characteristics of a gentle caress delivered at typical skin temperature. This provides a peripheral mechanism for signaling pleasant skin-to-skin contact in humans, which promotes interpersonal touch and affiliative behavior.

Passing ADHD from one generation to the next.

Prenatal and early postnatal exposure of the developing brain to nicotine (PNE) is a major risk factor for inducing attention deficit hyperactivity disorder (ADHD). Children born to mothers who smoke cigarettes before, during, or immediately after pregnancy have a twofold higher risk of developing ADHD. Zhu et al. show that hyperactivity and attention deficits induced by putting nicotine in the drinking water of pregnant mice is transmitted from one generation to the next via the maternal but not the paternal line of descent. The authors note:

A plausible mechanism for the transgenerational transmission of the PNE-induced brain and behavioral changes is heritable epigenetic modifications of the germ cell genome. Nicotine is known to produce DNA methylation in a number of genes, including the gene coding for monoamine oxidase, a key enzyme in the metabolism of dopamine and other monoamines.

Restoring vision to blind mice (and humans with RP or AMD?) with a photoswitch.

Age-related macular degeneration (AMD) and retinitis pigmentosa (RP) affect millions of people around the world and in their advanced stages lead to blindness. Studies in mouse models of these diseases have shown some promise in restoring vision but are either invasive (i.e., implantation of electronic chips) or irreversible (i.e., transplantation of photoreceptor progenitors or viral expression of optogenetic tools). Tochitsky et al. (click on the link to see the authors' fancy PR video of the work) have now performed introcular injection of a synthetic small molecule called DENAQ which is a red-shifted K+ channel photoswitch that exhibits trans to cis photoisomerization with visible light (450–550 nm) and relaxes rapidly to the trans configuration in the dark A single injection photosensitizes blind retinas with no photoreceptors to daylight intensity white light for a period of days with no toxicity. It restores light-elicited behavior and enables visual learning in blind mice. It is a prime drug candidate for vision restoration in patients with end-stage RP and AMD.

Figure of DENAQ from Mourot et al., ACS Chem. Neurosci., 2011, 2 (9), pp 536–543AMD.

Predicting risky choices from brain activity patterns

Helfinstein et al. find some predictive neural correlates of avoiding versus taking risks. Even course global patterns of brain activity reflect enhanced activity when preparing to avoid a risk, suggesting that risk taking may reflect a failure of control systems necessary to initiate a safe choice. It is changes in regions related to risk aversion that most reliably predict whether a subject will make a risky or safe choice. They

...used the Balloon Analog Risk Task (BART), in which subjects receive points as they pump up balloons but risk losing those points should the balloon explode before they choose to stop pumping and “cash out.” Each pump opportunity is a risky decision, where subjects must choose whether to pump again to gain more points or to cash out to secure those points already accrued. The structure of the task, where subjects make sequential risky choices with feedback, is common to many real-world risk-taking situations and matches both the economic and lay definition of risk, in that each successive pump opportunity for a given balloon has both greater variance in possible outcomes and increased exposure to loss. Performance on this task has also been shown, in numerous behavioral studies, to relate to self-reported sensation seeking and to naturalistic risk-taking behaviors, such as smoking, drug use, sexual risk-taking, and unsafe driving behaviors. Because performance on this task consistently correlates with naturalistic risk-taking behaviors, the cognitive processes at work during the task are likely to be comparable to those used during real-world risky decision making.

Here is their abstract:

Previous research has implicated a large network of brain regions in the processing of risk during decision making. However, it has not yet been determined if activity in these regions is predictive of choices on future risky decisions. Here, we examined functional MRI data from a large sample of healthy subjects performing a naturalistic risk-taking task and used a classification analysis approach to predict whether individuals would choose risky or safe options on upcoming trials. We were able to predict choice category successfully in 71.8% of cases. Searchlight analysis revealed a network of brain regions where activity patterns were reliably predictive of subsequent risk-taking behavior, including a number of regions known to play a role in control processes. Searchlights with significant predictive accuracy were primarily located in regions more active when preparing to avoid a risk than when preparing to engage in one, suggesting that risk taking may be due, in part, to a failure of the control systems necessary to initiate a safe choice. Additional analyses revealed that subject choice can be successfully predicted with minimal decrements in accuracy using highly condensed data, suggesting that information relevant for risky choice behavior is encoded in coarse global patterns of activation as well as within highly local activation within searchlights.

Senior Coolness

Swiss researchers Zimmermann and Grebe describe the outcome of analysis of in-depth interviews in German with 65 people aged 77 to 101, which runs counter to the narrative of very old age which tends to focus on deterioration, dementia and burden. Their subjects seem to rise above their problems with a kind of emotional nonchalance, take pleasure in the things they still can do, and choose not do dwell on issues of pain and other problem they can do little about. Here are the highlights and abstract from their article. The article cites many examples from their interviews to make their case (motivated readers can obtain a PDF of the article by emailing me).

Highlights

• Public perceptions of old age (80 +) focus largely on deficiency and loss.
• By contrast, elderly people (80 +) report ways in which they are able to live well.
• Living well in old age can be associated with the capacity to “keep cool”.
• This “senior coolness” renders personal and societal problems manageable.

Abstract

With demographic change becoming an ever more pressing issue in Germany, old age (80 +) is currently talked about above all in terms of being a problem. In mainstream discourse on the situation of the oldest old an interpretive framework has emerged that effectively rules out the possibility of people living positively and well in old age. With regard to both individual (personal) and collective (societal) spheres, negative images of old age dominate public debate. This is the starting point for an interdisciplinary research project designed to look at the ways in which people manage to “live well in old age in the face of vulnerability and finitude” — in express contrast to dominant negative perspectives. Based on the results of this project, the present article addresses an attitudinal and behavioral mode which we have coined “senior coolness”. Coolness here is understood as both a socio-cultural resource and an individualized habitus of everyday living. By providing an effective strategy of self-assertion, this ability can, as we show, be just as important for elderly people as for anyone else. “Senior coolness” is discussed, finally, as a phenomenon that testifies to the ways elderly people retain a positive outlook on life — especially in the face of difficult circumstances and powerful socio-cultural pressures.

In a similar vein, I would recommend reading New Yorker writer Roger Angell's article "This Old Man" about his life in the nineties.

Mindfulness and corporate America’s bottom line.

New Republic senior editor Evgeny Morozov writes a piece called “The Mindfulness Racket”. (I have been working on a brain/mind web lecture on the mindfulnesness / attentional / default / upstairs / downstairs themes, but the deluge of articles in these area is beginning to make me feel like I'm carrying coals to Newcastle.) Some edited clips from Morozov's article:

Mindfulness on the cover of Time magazine...Huffington publications’ stress-tracking app named “GPS for the Soul”…”digital sabbath”…”digital detox”…In essence, we are being urged to unplug-for an hour, a day, a week - so that we can resume our usual activities with even more vigor upon returning to the land of distraction..In our maddeningly complex world, where everything is in flux and defies comprehension, the only reasonable attitude is to renounce any efforts at control and adopt a Zen-like attitude of non-domination.

Huffington hopes that the pursuit of mindfulness can finally reconcile spirituality and capitalism…”So yes, I do want to talk about maximizing profits and beating expectations - by emphasizing the notion that what’s good for us as individuals is also good for corporate America’s bottom line”…

But couldn’t the “disconnectionists”…pursue an agenda a tad more radical than “digital detoxification”? Alexis Madrigal of The Atlantic complains “Individuals unplugging is not actually an answer to the biggest technological problems of our time just as any individual’s local, organic dietary habits don’t solve global agriculture’s issues.”

…why we disconnect matters: We can continue in today’s mode of treating disconnection as a way to recharge and regain productivity, or we can view it as a way to sabotage the addiction tactics of the acceleration distraction complex that is Silicon Valley. The former approach is reactionary but the latter can lead to emancipation, especially if such acts of refusal give rise to genuine social movements that will make problems of time and attention part of their political agendas - and not just the subject of hand-wringing by the Davos-based spirituality brigades…. We must be mindful of all this mindfulness.

Meditation and brain imaging of two kinds of love.

Judson Brewer and collaborators perform fMRI scans of experienced practitioners of loving kindness meditation, which fosters feelings of selfless love for others. Their abstract (below) notes their observations (but doesn't emphasize one of their more interesting findings: that the tranquility of selfless love without expectation of reward lowers activation of the areas activated by romantic love - which are the same reward areas activated by cocaine.)

Loving kindness is a form of meditation involving directed well-wishing, typically supported by the silent repetition of phrases such as “may all beings be happy,” to foster a feeling of selfless love. Here we used functional magnetic resonance imaging to assess the neural substrate of loving kindness meditation in experienced meditators and novices. We first assessed group differences in blood oxygen level-dependent (BOLD) signal during loving kindness meditation. We next used a relatively novel approach, the intrinsic connectivity distribution of functional connectivity, to identify regions that differ in intrinsic connectivity between groups, and then used a data-driven approach to seed-based connectivity analysis to identify which connections differ between groups. Our findings suggest group differences in brain regions involved in self-related processing and mind wandering, emotional processing, inner speech, and memory. Meditators showed overall reduced BOLD signal and intrinsic connectivity during loving kindness as compared to novices, more specifically in the posterior cingulate cortex/precuneus (PCC/PCu), a finding that is consistent with our prior work and other recent neuroimaging studies of meditation. Furthermore, meditators showed greater functional connectivity during loving kindness between the PCC/PCu and the left inferior frontal gyrus, whereas novices showed greater functional connectivity during loving kindness between the PCC/PCu and other cortical midline regions of the default mode network, the bilateral posterior insula lobe, and the bilateral parahippocampus/hippocampus. These novel findings suggest that loving kindness meditation involves a present-centered, selfless focus for meditators as compared to novices.

Neural signature of our own-race bias.

Wiese et al. examine the N170 signal (a component of event related potentials, or ERP recorded from electrodes placed on the head, which is maximal over occipito-temporal electrode sites). It has been linked with the structural encoding of faces. They suggest that ethnicity effects in the N170 reflect an early categorization of other-race faces into a social out-group, resulting in less efficient encoding and thus decreased memory.

Participants are more accurate at remembering faces of their own relative to another ethnic group (own-race bias, ORB). This phenomenon has been explained by reduced perceptual expertise, or alternatively, by the categorization of other-race faces into social out-groups and reduced effort to individuate such faces. We examined event-related potential (ERP) correlates of the ORB, testing recognition memory for Asian and Caucasian faces in Caucasian and Asian participants. Both groups demonstrated a significant ORB in recognition memory. ERPs revealed more negative N170 amplitudes for other-race faces in both groups, probably reflecting more effortful structural encoding. Importantly, the ethnicity effect in left-hemispheric N170 during learning correlated significantly with the behavioral ORB. Similarly, in the subsequent N250, both groups demonstrated more negative amplitudes for other-race faces, and during test phases, this effect correlated significantly with the ORB. We suggest that ethnicity effects in the N170 reflect an early categorization of other-race faces into a social out-group, resulting in less efficient encoding and thus decreased memory. Moreover, ethnicity effects in the N250 may represent the “tagging” of other-race faces as perceptually salient, which hampers the recognition of these faces.

Awesome Images

I want to pass on to MindBlog reader two striking galleries of open access images. The first is Science Magazine's Visualization Challenge. One of its striking images is "Cortex in Metallic Pastels":

The second collection shows natural and manmade places with very unusual colors.

The social (and medical) pathology of correlating inner worth with wealth.

A recent piece by Wilkinson and Pickett in the NYTimes deserves notice. They comment on how wealth inequality is not only divisive and socially corrosive, but also damaging to individuals' mental health. They cite their work showing that:

...major and minor mental illnesses were three times as common in societies where there were bigger income differences between rich and poor. In other words, an American is likely to know three times as many people with depression or anxiety problems as someone in Japan or Germany.

Another study

...looking at the 50 American states, discovered that after taking account of age, income and educational differences, depression was more common in states with greater income inequality. Another, which combined data from over 100 surveys in 26 countries, found that schizophrenia was about three times as common in more unequal societies as it was in more equal ones.

Other clips:

...a wide range of mental disorders might originate in a “dominance behavioral system.” This part of our evolved psychological makeup, almost universal in mammals, enables us to recognize and respond to social ranking systems based on hierarchy and power...One of the important effects of wider income differences between rich and poor is to intensify the issues of dominance and subordination, and feelings of superiority and inferiority.

Humans instinctively know how to cooperate and create social ties, but we also know how to engage in status competition — how to be snobs and how to talk ourselves up. We use these alternative social strategies almost every day of our lives, but crucially, inequality shifts the balance between them...It is hard to avoid the conclusion that we become less nice people in more unequal societies. But we are less nice and less happy: Greater inequality redoubles status anxiety, damaging our mental health and distorting our personalities — wherever we are on the social spectrum.

The article doesn't mention the physical effects that are another major consequence of inequality. Feeling inferior correlates with feeling more helpless than powerful, and hundreds of studies have shown that feelings of helplessness lead to increased disease, lowered immune function, increased anxiety, etc. (enter 'helplessness' in the search box in the left column to see Mindblog posts on this topic.)

Our pupil dilation reflects decision related choice.

Pupil size is known to be increased by effortful decisions. The current supposition is that decision-related pupil dilation tracks the activity of neuromodulatory systems of the brainstem—in particular, the noradrenergic locus coeruleus and, possibly the cholinergic basal forebrain systems. These neuromodulatory systems activate briefly during perceptual decisions such as visual target detection.

de Gee et al. now provide evidence that pupil dilation reflects not the termination of the decision process but rather events during the course of decision formation. The amplitude of pupil dilation is bigger during decision formation for yes than for no choices, and it is strongest in conservative subjects choosing yes against their bias. Imagine what advertisers or merchandizers training cameras on their customers might be able to do with this!

A number of studies have shown that pupil size increases transiently during effortful decisions. These decision-related changes in pupil size are mediated by central neuromodulatory systems, which also influence the internal state of brain regions engaged in decision making. It has been proposed that pupil-linked neuromodulatory systems are activated by the termination of decision processes, and, consequently, that these systems primarily affect the postdecisional brain state. Here, we present pupil results that run contrary to this proposal, suggesting an important intradecisional role. We measured pupil size while subjects formed protracted decisions about the presence or absence (“yes” vs. “no”) of a visual contrast signal embedded in dynamic noise. Linear systems analysis revealed that the pupil was significantly driven by a sustained input throughout the course of the decision formation. This sustained component was larger than the transient component during the final choice (indicated by button press). The overall amplitude of pupil dilation during decision formation was bigger before yes than no choices, irrespective of the physical presence of the target signal. Remarkably, the magnitude of this pupil choice effect (yes > no) reflected the individual criterion: it was strongest in conservative subjects choosing yes against their bias. We conclude that the central neuromodulatory systems controlling pupil size are continuously engaged during decision formation in a way that reveals how the upcoming choice relates to the decision maker’s attitude. Changes in brain state seem to interact with biased decision making in the face of uncertainty.

Reaction time and longevity.

Hagger-Johnson et al. note a correlation between reaction times (doing a button press as quickly as possible after a light flashes on a computer screen) and mortality in 5,145 adults ages 20 to 59 (measured in the late 1980s and early ’90s). The subjects were followed to see how many would be alive after 15 years. After controlling for smoking, drinking, and other factors, the authors found that those with slower reaction times (one standard deviation less than average) were 25 percent more likely to die of any cause, and 36 percent more likely to die of cardiovascular disease, than those with faster reactions. There was no correlation with cancer deaths. The reasons for the statistical correlation is not clear, but the obvious idea is that slower reaction times may reflect brain or nervous system problems that increase morbidity.

Genetic predisposition of our behavioral responses.

Gregory sets the context for a recent article by Skuze et al. on how genes for our oxytocin receptors can influence our social recognition skills:

...the notion that the evolution of our behavioral response is solely shaped by the events themselves is challenged by studies that highlight how interindividual differences in social perception and response to social cues may be determined by underlying genetic predisposition. These studies are establishing that our DNA contains heritable variants that contribute to subtle differences in social cognition. These sequence variants are contained within genes that not only play a role in the relationship that parents may have with their offspring but also how we recognize or react to one another. In PNAS, Skuse et al.investigate the signaling pathways of neuropeptides oxytocin (OT) and arginine-vasopressin (AVP) to identify DNA polymorphisms that might explain interindividual differences in response to social cues. The authors genotyped a series of SNPs from the OT and AVP receptor regions to identify SNPs that account for variation in response to tests of social cognition in autism spectrum disorder (ASD) families.

Here is the Skuze et al. abstract:

The neuropeptides oxytocin and vasopressin are evolutionarily conserved regulators of social perception and behavior. Evidence is building that they are critically involved in the development of social recognition skills within rodent species, primates, and humans. We investigated whether common polymorphisms in the genes encoding the oxytocin and vasopressin 1a receptors influence social memory for faces. Our sample comprised 198 families, from the United Kingdom and Finland, in whom a single child had been diagnosed with high-functioning autism. Previous research has shown that impaired social perception, characteristic of autism, extends to the first-degree relatives of autistic individuals, implying heritable risk. Assessments of face recognition memory, discrimination of facial emotions, and direction of gaze detection were standardized for age (7–60 y) and sex. A common SNP (single nucleotide polymorphism) in the oxytocin receptor (rs237887) was strongly associated with recognition memory in combined probands, parents, and siblings after correction for multiple comparisons. Homozygotes for the ancestral A allele had impairments in the range −0.6 to −1.15 SD scores, irrespective of their diagnostic status. Our findings imply that a critical role for the oxytocin system in social recognition has been conserved across perceptual boundaries through evolution, from olfaction in rodents to visual memory in humans.

Different cultures, different computation systems

Bender and Beller report that a mixed number system superimposing three binary steps onto a decimal structure was invented long before Leibniz’s description of binary numerals, for easier calculations to measure mixed quantities of yams and other garden products, on the Pacific island of Mangareva. It did not arise on other islands of the Pacific with similar ecologies.

...the mixed counting system in Mangarevan...is unique in that it had three binary steps superposed onto a decimal structure. In showing how these steps affect calculation, our analysis yields important insights for theorizing on numerical cognition: counting systems serve as complex cultural tools for numerical cognition, apparently unwieldy systems may in fact be cognitively advantageous, and such advantageous systems can be—and have been—developed by nonindustrialized societies and in the absence of notational systems. These insights also help to dismiss simple notions of cultural complexity as a homogenous state and emphasize that investigating cultural diversity is not merely an optional extra, but a must.

From their conclusions:

Summarizing our results, it seems clear that superposing a decimal system with binary steps is indeed advantageous, as described by Leibniz because it allows arduous calculations and retrieval of addition facts to be replaced by simple transformations in the binary range. Crucially, these advantages are not vitiated by the downside of longer number representations also anticipated by Leibniz. The decimal basis of the system guarantees that number representations remain relatively compact. The mixed system thus neutralizes the tradeoff associated with base size by combining the benefits of a small base (fewer or no addition facts) with the benefits of a larger base (compact representation). Actually, both of these implications adjust to the constraints on working memory and thereby benefit mental arithmetic: the more compact representation relieves cognitive load in retaining information, and the reduction in addition facts relieves cognitive load in processing. The main cost inflicted by this mixing is an increase in irregularity, which requires additional lexemes and rules and thus affects the ease with which a system is learned and mastered....Apparently, its users favored the benefits of the mixed system over the regularity of the general decimal system, as they developed the mixed system out of the purely decimal system in wide use across Polynesia.

Why electroconvulsive therapy works in mood disorders.

Dukart et al. make the interesting observation that the controversial procedure of electroconvulsive therapy causes changes in gray matter volume in the brain areas that are implicated as abnormal in refractory major depression and manic depression:

There remains much scientific, clinical, and ethical controversy concerning the use of electroconvulsive therapy (ECT) for psychiatric disorders stemming from a lack of information and knowledge about how such treatment might work, given its nonspecific and spatially unfocused nature. The mode of action of ECT has even been ascribed to a “barbaric” form of placebo effect. Here we show differential, highly specific, spatially distributed effects of ECT on regional brain structure in two populations: patients with unipolar or bipolar disorder. Unipolar and bipolar disorders respond differentially to ECT and the associated local brain-volume changes, which occur in areas previously associated with these diseases, correlate with symptom severity and the therapeutic effect. Our unique evidence shows that electrophysical therapeutic effects, although applied generally, take on regional significance through interactions with brain pathophysiology.

Constancy of our social signatures.

Robin Dunbar and collaborators have done an interesting examination of the persistence of how many close contacts we maintain (family and close friends) over time, even as the identities of those who are close to us changes. Dunbar is the guy who is well known for his early work showing a correlation between the brain size of social mammals and the size of their social groups. His line relating brain size to group size put the maximal or optimal size of human groups at about 150 individuals. (Enter 'Dunbar' in the search box to the left to see several MindBlog posts on his work.) Here are some clips from their article.

...It appears that having strong and supportive relationships, characterized by closeness and emotional intensity, is essential for health and well-being in both humans and other primates. At the same time, there is a higher cost to maintaining closer relationships, reflected in the amount of effort required to maintain a relation at the desired level of emotional closeness. Because of this, the number of emotionally intense relationships is typically small. Moreover, it has been suggested that ego networks, the sets of ties individuals (egos) have to their friends and family (alters), may be subject to more general constraints associated with limits on human abilities to interact with large numbers of alters. Although there are obvious constraints on the time available for interactions, additional constraints may also arise through limits on memory capacity or other cognitive abilities.

..it is reasonable to ask whether such mechanisms shape these networks in similar ways under different circumstances, giving rise to some characteristic features that persist over time despite network turnover...We combine detailed, autorecorded data from mobile phone call records with survey data. These were collected during a study that tracked changes in the ego networks of 24 students over 18 mo as they made the transition from school to university or work. These changes in personal circumstances result in a period of flux for the social relationships of the participants, with many alters both leaving and entering their networks. This provides a unique setting for studying network-level structure and its response to major changes in social circumstances.

Our results establish three unique findings: (i) There is a consistent, broad, and robust pattern in the way people allocate their communication across the members of their social network, with a small number of top-ranked, emotionally close alters receiving a disproportionately large fraction of calls; (ii) within this general pattern, there is clear individual-level variation so that each individual has a characteristic social signature depicting his or her particular way of communication allocation; and (iii) this individual social signature remains stable and retains its characteristic shape over time and is only weakly affected by network turnover. Thus, individuals appear to differ in how they allocate their available time to their alters, irrespective of who these alters are. Further, our subsidiary analyses (SI Text) suggest that this finding applies not just to call frequencies, because the frequency of calls to an alter correlates with emotional closeness and frequency of face-to-face interactions.

Here is their summary abstract:

We combine cell phone data with survey responses to show that a person’s social signature, as we call the pattern of their interactions with different friends and family members, is remarkably robust. People focus a high proportion of their communication efforts on a small number of individuals, and this behavior persists even when there are changes in the identity of the individuals involved. Although social signatures vary between individuals, a given individual appears to retain a specific social signature over time. Our results are likely to reflect limitations in the ability of humans to maintain many emotionally close relationships, both because of limited time and because the emotional “capital” that individuals can allocate between family members and friends is finite.