Deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VC/VS) reduces symptoms of intractable obsessive-compulsive disorder (OCD), but the mechanism of action is unknown. OCD is characterized by avoidance behaviors that fail to extinguish, and DBS could act, in part, by facilitating extinction of fear. We investigated this possibility by using auditory fear conditioning in rats, for which the circuits of fear extinction are well characterized. We found that DBS of the VS (the VC/VS homolog in rats) during extinction training reduced fear expression and strengthened extinction memory. Facilitation of extinction was observed for a specific zone of dorsomedial VS, just above the anterior commissure; stimulation of more ventrolateral sites in VS impaired extinction. DBS effects could not be obtained with pharmacological inactivation of either dorsomedial VS or ventrolateral VS, suggesting an extrastriatal mechanism. Accordingly, DBS of dorsomedial VS (but not ventrolateral VS) increased expression of a plasticity marker in the prelimbic and infralimbic prefrontal cortices, the orbitofrontal cortex, the amygdala central nucleus (lateral division), and intercalated cells, areas known to learn and express extinction. Facilitation of fear extinction suggests that, in accord with clinical observations, DBS could augment the effectiveness of cognitive behavioral therapies for OCD.
Creativity is a highly sought-after skill. Prescriptive advice for inspiring creativity abounds in the form of metaphors: People are encouraged to “think outside the box,” to consider a problem “on one hand, then on the other hand,” and to “put two and two together” to achieve creative breakthroughs. These metaphors suggest a connection between concrete bodily experiences and creative cognition. Inspired by recent advances in the understanding of body-mind linkages in the research on embodied cognition, we explored whether enacting metaphors for creativity enhances creative problem solving. Our findings from five studies revealed that both physical and psychological embodiment of metaphors for creativity promoted convergent thinking and divergent thinking (i.e., fluency, flexibility, or originality) in problem solving. Going beyond prior research, which focused primarily on the kind of embodiment that primes preexisting knowledge, we provide the first evidence that embodiment can also activate cognitive processes that facilitate the generation of new ideas and connections.
Throughout vertebrate phylogeny, testosterone has motivated animals to obtain and maintain social dominance—a fact suggesting that unconscious primordial brain mechanisms are involved in social dominance. In humans, however, the prevailing view is that the neocortex is in control of primordial drives, and testosterone is thought to promote social dominance via conscious feelings of superiority, indefatigability, strength, and anger. Here we show that testosterone administration in humans prolongs dominant staring into the eyes of threatening faces that are viewed outside of awareness, without affecting consciously experienced feelings. These findings reveal that testosterone motivates social dominance in humans in much the same ways that it does in other vertebrates: involuntarily, automatically, and unconsciously.
Literature is a form of expression whose temporal structure, both in content and style, provides a historical record of the evolution of culture. In this work we take on a quantitative analysis of literary style and conduct the first large-scale temporal stylometric study of literature by using the vast holdings in the Project Gutenberg Digital Library corpus. We find temporal stylistic localization among authors through the analysis of the similarity structure in feature vectors derived from content-free word usage, nonhomogeneous decay rates of stylistic influence, and an accelerating rate of decay of influence among modern authors. Within a given time period we also find evidence for stylistic coherence with a given literary topic, such that writers in different fields adopt different literary styles. This study gives quantitative support to the notion of a literary “style of a time” with a strong trend toward increasingly contemporaneous stylistic influence.It seems a bit amazing that their analysis of the use of 307 content-free words that included prepositions, articles, conjunctions, “to be” verbs, and some common nouns and pronouns allowed them to cluster authors in time and by narrative theme, and that content-free word frequencies were found to be fairly faithfully transmitted among authors of a similar period, even when imitation at this level of textual resolution seems to be out of the question. Moving into the present, this imitation becomes increasingly localized to our contemporaries. Further edited clips:
We propose that for the earliest periods in our dataset, and through the early modern period, the number of published works remained relatively low. This allowed authors to have sufficient time to sample (read) very broadly from the full range of historically published works. Common phrasing, and norms of syntax and grammar, remain relatively unchanged for long periods of time. This generates decay rates in similarity as a function of temporal distance that are not significantly different from the average, because authors are influenced by models distributed uniformly in time. However, for more recent authors, the number of possible choices of books to read has increased dramatically, and with a finite amount of time, a subset of these works must be chosen, leading to rather heterogeneous reading patterns and a greater overall diversity of authored works. The pattern accelerates in the later modern period, with even more authors to choose from and selection dominated by contemporaneous authors. This suggests a simple evolutionary model for patterns of influence.
The negative influence of authors from a preceding generation in the period 1907–1952 could be explained by the Modernist movement. Modernist authors, who are contained within this time period, display a radical shift in style as they reject their immediate stylistic predecessors yet remain a part of a dominant movement that included many of their contemporaries. The contemporary influence of writing programs and their often close readings of contemporary works and feedback (sometimes called “reflexive modernism”) has also been suggested to contribute to this effect. The overall pattern that we find is that the stylistic influence of the past is diminishing at an increasing rate, which suggests that style itself is evolving at an accelerating pace.
The patterns of influence are a first discovery from the corpus. Implicit in this is a temporal clustering of similarity and quantitative support for the qualitative suggestions of a notion of a “style of a time.” It is also worth noting that the implicit temporal clustering of similarity is not an exclusively temporal phenomenon. A network representation of the authors reveals evidence of thematic clustering as well. Examples include interesting groupings of English poets and playwrights, military leaders, and a collection of important naturalists, social thinkers, and historians. This is suggestive and supportive of the hypothesis that word frequencies are not only typical of a given time but also of a field of inquiry. Historians and naturalists do not only write about different topics, they write about them differently. Taken together with the patterns of decay in influence this suggests that whereas authors of the 18th and 19th centuries continued to be influenced by previous centuries, authors of the late 20th century are strongly influenced by authors from their own decade. The so-called “anxiety of influence”, whereby authors are understood in terms of their response to canonical precursors, is becoming an “anxiety of impotence,” in which the past exerts a diminishing stylistic influence on the present. These results are consistent with many complex, scaling phenomena such as those found in urban and technological systems, where there has been an accelerating rate of change into the present. This is a rather intriguing pattern of short-term cultural evolution that is different from the constant rates of change reported for names and pottery or the reduced rates of lexical substitution of frequently used words over thousands of years. Further analysis will elucidate not only the transmission mechanisms generating temporally localized styles but additional stylistic factors that help differentiate the style of one author from that of another.
-In 70% of the population, biological and social clocks differ by >1 hr (social jetlag) -Social jetlag is a predictor of BMI, especially for overweight individuals -The decrease of sleep duration over the past decade concerns only workdays -Individuals are progressively exposed to decreasing light, and their chronotypes delayAbstract
Obesity has reached crisis proportions in industrialized societies. Many factors converge to yield increased body mass index (BMI). Among these is sleep duration. The circadian clock controls sleep timing through the process of entrainment. Chronotype describes individual differences in sleep timing, and it is determined by genetic background, age, sex, and environment (e.g., light exposure). Social jetlag quantifies the discrepancy that often arises between circadian and social clocks, which results in chronic sleep loss. The circadian clock also regulates energy homeostasis, and its disruption—as with social jetlag—may contribute to weight-related pathologies. Here, we report the results from a large-scale epidemiological study, showing that, beyond sleep duration, social jetlag is associated with increased BMI. Our results demonstrate that living “against the clock” may be a factor contributing to the epidemic of obesity. This is of key importance in pending discussions on the implementation of Daylight Saving Time and on work or school times, which all contribute to the amount of social jetlag accrued by an individual. Our data suggest that improving the correspondence between biological and social clocks will contribute to the management of obesity.
Detecting and responding to biological stimuli such as predators or potential mates is a fundamental and adaptive capability, supported by rain areas such as the posterior superior temporal sulcus (pSTS) which is biased for processing biological motion. The pSTS and the parietofrontal mirror system form part of a wider action observation network (AON), which is thought to underlie many social abilities. Motor resonance (MR) is the activation of matching motor representations during observation of action(s) made by others, and could index mirror activity within the wider AON.
Understanding the neural basis of social behavior has become an important goal for cognitive neuroscience and a key aim is to link neural processes observed in the laboratory to more naturalistic social behaviors in real-world contexts. Although it is accepted that mirror mechanisms contribute to the occurrence of motor resonance (MR) and are common to action execution, observation, and imitation, questions remain about mirror (and MR) involvement in real social behavior and in processing nonhuman actions. To determine whether social interaction primes the MR system, groups of participants engaged or did not engage in a social interaction before observing human or robotic actions. During observation, MR was assessed via motor-evoked potentials elicited with transcranial magnetic stimulation. Compared with participants who did not engage in a prior social interaction, participants who engaged in the social interaction showed a significant increase in MR for human actions. In contrast, social interaction did not increase MR for robot actions. Thus, naturalistic social interaction and laboratory action observation tasks appear to involve common MR mechanisms, and recent experience tunes the system to particular agent types.
Establishing a function for the neuromodulator serotonin in human decision-making has proved remarkably difficult because if its complex role in reward and punishment processing. In a novel choice task where actions led concurrently and independently to the stochastic delivery of both money and pain, we studied the impact of decreased brain serotonin induced by acute dietary tryptophan depletion. Depletion selectively impaired both behavioral and neural representations of reward outcome value, and hence the effective exchange rate by which rewards and punishments were compared. This effect was computationally and anatomically distinct from a separate effect on increasing outcome-independent choice perseveration. Our results provide evidence for a surprising role for serotonin in reward processing, while illustrating its complex and multifarious effects.
Oxytocin, vasopressin, and their receptor genes influence prosocial behavior in the laboratory and in the context of close relationships. These peptides may also promote social engagement following threat. However, the scope of their prosocial effects is unknown. We examined oxytocin receptor (OXTR) polymorphism rs53576, as well as vasopressin receptor 1a (AVPR1a) polymorphisms rs1 and rs3 in a national sample of U.S. residents (n = 348). These polymorphisms interacted with perceived threat to predict engagement in volunteer work or charitable activities and commitment to civic duty. Specifically, greater perceived threat predicted engagement in fewer charitable activities for individuals with A/A and A/G genotypes of OXTR rs53576, but not for G/G individuals. Similarly, greater perceived threat predicted lower commitment to civic duty for individuals with one or two short alleles for AVPR1a rs1, but not for individuals with only long alleles. Oxytocin, vasopressin, and their receptor genes may significantly influence prosocial behavior and may lie at the core of the caregiving behavioral system.
Stress-related variation in the intrauterine milieu may impact brain development and emergent function, with long-term implications in terms of susceptibility for affective disorders. Studies in animals suggest limbic regions in the developing brain are particularly sensitive to exposure to the stress hormone cortisol. However, the nature, magnitude, and time course of these effects have not yet been adequately characterized in humans. A prospective, longitudinal study was conducted in 65 normal, healthy mother–child dyads to examine the association of maternal cortisol in early, mid-, and late gestation with subsequent measures at approximately 7 y age of child amygdala and hippocampus volume and affective problems. After accounting for the effects of potential confounding pre- and postnatal factors, higher maternal cortisol levels in earlier but not later gestation was associated with a larger right amygdala volume in girls (a 1 SD increase in cortisol was associated with a 6.4% increase in right amygdala volume), but not in boys. Moreover, higher maternal cortisol levels in early gestation was associated with more affective problems in girls, and this association was mediated, in part, by amygdala volume. No association between maternal cortisol in pregnancy and child hippocampus volume was observed in either sex. The current findings represent, to the best of our knowledge, the first report linking maternal stress hormone levels in human pregnancy with subsequent child amygdala volume and affect. The results underscore the importance of the intrauterine environment and suggest the origins of neuropsychiatric disorders may have their foundations early in life.
Neuroscience has made considerable progress in understanding the neural substrates supporting cognitive performance in a number of domains, including memory, perception, and decision making. In contrast, how the human brain generates metacognitive awareness of task performance remains unclear. Here, we address this question by asking participants to perform perceptual decisions while providing concurrent metacognitive reports during fMRI scanning. We show that activity in right rostrolateral prefrontal cortex (rlPFC) satisfies three constraints for a role in metacognitive aspects of decision-making. Right rlPFC showed greater activity during self-report compared to a matched control condition, activity in this region correlated with reported confidence, and the strength of the relationship between activity and confidence predicted metacognitive ability across individuals. In addition, functional connectivity between right rlPFC and both contralateral PFC and visual cortex increased during metacognitive reports. We discuss these findings in a theoretical framework where rlPFC re-represents object-level decision uncertainty to facilitate metacognitive report.I'll also pass on Figure 5 and it's legend from the text:
Individual difference and connectivity analyses. The top panel illustrates the significant correlation between confidence-related activity in right rlPFC and metacognitive accuracy across subjects. The bottom panel depicts results of an exploratory psychophysiological interaction analysis (displayed at p < 0.001, uncorrected), revealing whole-brain corrected (p < 0.05) increases in connectivity between right rlPFC and visual cortex (lingual gyrus) and between right rlPFC and left dlPFC in Report compared to Follow trials.
WHY are we thinking so much about thinking these days?...Jonah Lehrer’s “Imagine: How Creativity Works,” ...Charles Duhigg’s book “The Power of Habit: Why We Do What We Do in Life and Business,” ...“Subliminal: How Your Unconscious Mind Rules Your Behavior,” by Leonard Mlodinow...Kahneman's “Thinking, Fast and Slow” goes to the heart of the matter: How aware are we of the invisible forces of brain chemistry, social cues and temperament that determine how we think and act? Has the concept of free will gone out the window?
These books possess a unifying theme: The choices we make in day-to-day life are prompted by impulses lodged deep within the nervous system. Not only are we not masters of our fate; we are captives of biological determinism. Once we enter the portals of the strange neuronal world known as the brain, we discover that — to put the matter plainly — we have no idea what we’re doing.
The 18th-century philosopher David Hume (much quoted by Mr. Lehrer) didn’t have an M.R.I. scanner at his disposal, but he framed the question in much the same way. His major work, “A Treatise of Human Nature,” explored the ways in which habit, or “custom,” rules our lives. Hume’s experiments with perception — how we respond to colors, distance, numerical sets — prefigure the rigorous science of Professor Kahneman. His intent was to show us “the natural infirmity and unsteadiness both of our imagination and senses.” Consciousness, like philosophy itself, stands on a “weak foundation.”
If Hume seems modern, William James reads like a contemporary. Writing toward the end of the 19th century, James addressed the same question that had concerned Hume — how the unconscious operates as a physical process, not just, as Freud would have it, a mental one. In his now-classic essay, “Habit,” he argued that even our most complex acts are reflexive — “concatenated discharges in the nerve-centres.” ...we can train ourselves to change if we work at it hard enough. Self-awareness sets us free. “The great thing, then, in all education,” writes James, “is to make our nervous system our ally instead of our enemy.”
Does this mean we have no “agency,” no capacity to act on our own? Or can autonomy thrive within the prison of self-ignorance? “We have to believe it does,” says Steven Lukes, a professor of sociology at New York University highly admired for his work in moral philosophy. “If we seriously thought that our intentions made no difference to how we behave, we couldn’t go on using the language of ethics. How would we go on living the lives we live?” Or doing what we think is right? “People have free will when they ‘feel’ they have free will,” says Professor Kahneman. “If we didn’t believe in it, we would have no responsibility.”
But of course what one “feels,” as we’ve learned from all these books, could well be — indeed, probably is — an illusion. As Timothy Wilson puts it with haunting simplicity: “We are strangers to ourselves.” Hopefully...Strangers who can learn how to be friends.The sentiments above are very much in the vein of my "I-Illusion" web lecture.
Bilingualism profoundly affects the brain, yielding functional and structural changes in cortical regions dedicated to language processing and executive function [Crinion J, et al. (2006) Science 312:1537–1540; Kim KHS, et al. (1997) Nature 388:171–174]. Comparatively, musical training, another type of sensory enrichment, translates to expertise in cognitive processing and refined biological processing of sound in both cortical and subcortical structures. Therefore, we asked whether bilingualism can also promote experience-dependent plasticity in subcortical auditory processing. We found that adolescent bilinguals, listening to the speech syllable [da], encoded the stimulus more robustly than age-matched monolinguals. Specifically, bilinguals showed enhanced encoding of the fundamental frequency, a feature known to underlie pitch perception and grouping of auditory objects. This enhancement was associated with executive function advantages. Thus, through experience-related tuning of attention, the bilingual auditory system becomes highly efficient in automatically processing sound. This study provides biological evidence for system-wide neural plasticity in auditory experts that facilitates a tight coupling of sensory and cognitive functions.
According to decades of research on affective motivation in the human brain, approach motivational states are supported primarily by the left hemisphere and avoidance states by the right hemisphere. The underlying cause of this specialization, however, has remained unknown. Here we conducted a first test of the Sword and Shield Hypothesis (SSH), according to which the hemispheric laterality of affective motivation depends on the laterality of motor control for the dominant hand (i.e., the “sword hand," used preferentially to perform approach actions) and the nondominant hand (i.e., the “shield hand," used preferentially to perform avoidance actions).
To determine whether the laterality of approach motivation varies with handedness, we measured alpha-band power (an inverse index of neural activity) in right- and left-handers during resting-state electroencephalography and analyzed hemispheric alpha-power asymmetries as a function of the participants' trait approach motivational tendencies. Stronger approach motivation was associated with more left-hemisphere activity in right-handers, but with more right-hemisphere activity in left-handers.
The hemispheric correlates of approach motivation reversed between right- and left-handers, consistent with the way they typically use their dominant and nondominant hands to perform approach and avoidance actions. In both right- and left-handers, approach motivation was lateralized to the same hemisphere that controls the dominant hand. This covariation between neural systems for action and emotion provides initial support for the SSH.
Physical activity improves learning and hippocampal neurogenesis. It is unknown whether compounds that increase endurance in muscle also enhance cognition. We investigated the effects of endurance factors, peroxisome proliferator-activated receptor δ agonist GW501516 and AICAR, activator of AMP-activated protein kinase on memory and neurogenesis. Mice were injected with GW for 7 d or AICAR for 7 or 14 d. Two weeks thereafter mice were tested in the Morris water maze. AICAR (7 d) and GW improved spatial memory. Moreover, AICAR significantly, and GW modestly, elevated dentate gyrus neurogenesis. Thus, pharmacological activation of skeletal muscle may mediate cognitive effects.
Since Darwin’s seminal works, the universality of facial expressions of emotion has remained one of the longest standing debates in the biological and social sciences. Briefly stated, the universality hypothesis claims that all humans communicate six basic internal emotional states (happy, surprise, fear, disgust, anger, and sad) using the same facial movements by virtue of their biological and evolutionary origins [Susskind JM, et al. (2008) Nat Neurosci 11:843–850]. Here, we refute this assumed universality. Using a unique computer graphics platform that combines generative grammars [Chomsky N (1965) MIT Press, Cambridge, MA] with visual perception, we accessed the mind’s eye of 30 Western and Eastern culture individuals and reconstructed their mental representations of the six basic facial expressions of emotion. Cross-cultural comparisons of the mental representations challenge universality on two separate counts. First, whereas Westerners represent each of the six basic emotions with a distinct set of facial movements common to the group, Easterners do not. Second, Easterners represent emotional intensity with distinctive dynamic eye activity. By refuting the long-standing universality hypothesis, our data highlight the powerful influence of culture on shaping basic behaviors once considered biologically hardwired. Consequently, our data open a unique nature–nurture debate across broad fields from evolutionary psychology and social neuroscience to social networking via digital avatars.
Variation in the social environment is a fundamental component of many vertebrate societies. In humans and other primates, adverse social environments often translate into lasting physiological costs. The biological mechanisms associated with these effects are therefore of great interest, both for understanding the evolutionary impacts of social behavior and in the context of human health. However, large gaps remain in our understanding of the mechanisms that mediate these effects at the molecular level. Here we addressed these questions by leveraging the power of an experimental system that consisted of 10 social groups of female macaques, in which each individual's social status (i.e., dominance rank) could be experimentally controlled. Using this paradigm, we show that dominance rank results in a widespread, yet plastic, imprint on gene regulation, such that peripheral blood mononuclear cell gene expression data alone predict social status with 80% accuracy. We investigated the mechanistic basis of these effects using cell type-specific gene expression profiling and glucocorticoid resistance assays, which together contributed to rank effects on gene expression levels for 694 (70%) of the 987 rank-related genes. We also explored the possible contribution of DNA methylation levels to these effects, and identified global associations between dominance rank and methylation profiles that suggest epigenetic flexibility in response to status-related behavioral cues. Together, these results illuminate the importance of the molecular response to social conditions, particularly in the immune system, and demonstrate a key role for gene regulation in linking the social environment to individual physiology.
Individuals are willing to sacrifice their own resources to promote equality in groups. These costly choices promote equality and are associated with behavior that supports cooperation in humans, but little is known about the brain processes involved. We use functional MRI to study egalitarian preferences based on behavior observed in the “random income game.” In this game, subjects decide whether to pay a cost to alter group members’ randomly allocated incomes. We specifically examine whether egalitarian behavior is associated with neural activity in the ventromedial prefrontal cortex and the insular cortex, two regions that have been shown to be related to social preferences. Consistent with previous studies, we find significant activation in both regions; however, only the insular cortex activations are significantly associated with measures of revealed and expressed egalitarian preferences elicited outside the scanner. These results are consistent with the notion that brain mechanisms involved in experiencing the emotional states of others underlie egalitarian behavior in humans.From their discussion:
...this experiment shows that some parts of the brain are more active during egalitarian outcomes, and these activations are correlated with egalitarian behavior inside the scanner. However, a more crucial result is that the activations are also correlated with behavior outside the scanner, including self-reported preferences for egalitarian outcomes and game behavior that reveals how willing subjects are to use their own resources to obtain egalitarian outcomes within their groups. Taken together, the evidence suggests that the anterior insular cortex plays a critical role in egalitarian behavior in humans. This conclusion is consistent with a broader view of the insular cortex as a neural substrate that processes the relationship of the individual with respect to his or her environment. The predominately left-lateralized activation may point toward the possibility of a positive valence or energy-preserving mode related processing during egalitarian behavior (i.e., individuals may see the group as a greater good that is worth preserving). The fact that the insula is directly involved in physiological, food, and pain-related processing supports the general notion that prosocial behavior, which is important for survival of both the individual and the group/species, is implemented on a fundamental physiological level similar to breathing, heartbeat, hunger, and pain.
Adam Smith contended that moral sentiments like egalitarianism derived from a “fellow-feeling” that would increase with our level of sympathy for others, predicting not merely aversion to inequity, but also our propensity to engage in egalitarian behaviors. The evidence here supports such an interpretation. Although individuals may experience internal rewards when punishing antisocial behavior and may have preferences for social equality, our results suggest that it is the brain mechanisms involved in experiencing the emotional and social states of self and others that appear to be driving egalitarian behaviors.
Our results have important implications for theories of the evolution of prosocial behavior that suggest culturally transmitted “leveling mechanisms”—for example, food sharing and monogamy—stifle within-group competition and create circumstances in which intergroup antagonism generates selective pressure for altruistic behaviors. A concern for equality may have originally evolved because it fostered the conditions necessary for early human groups to maintain a high level of cooperation. Future research should focus on the interconnectivity of regions of the brain involved in egalitarianism and altruism to better understand how these two behaviors may have coevolved.