Friday, November 30, 2012

Where our brains predict romantic attraction at a glance.

From Cooper et al:

Humans frequently make real-world decisions based on rapid evaluations of minimal information; for example, should we talk to an attractive stranger at a party? Little is known, however, about how the brain makes rapid evaluations with real and immediate social consequences. To address this question, we scanned participants with functional magnetic resonance imaging (fMRI) while they viewed photos of individuals that they subsequently met at real-life “speed-dating” events. Neural activity in two areas of dorsomedial prefrontal cortex (DMPFC), paracingulate cortex, and rostromedial prefrontal cortex (RMPFC) was predictive of whether each individual would be ultimately pursued for a romantic relationship or rejected. Activity in these areas was attributable to two distinct components of romantic evaluation: either consensus judgments about physical beauty (paracingulate cortex) or individualized preferences based on a partner's perceived personality (RMPFC). These data identify novel computational roles for these regions of the DMPFC in even very rapid social evaluations. Even a first glance, then, can accurately predict romantic desire, but that glance involves a mix of physical and psychological judgments that depend on specific regions of DMPFC.

Neural predictors of subsequent decision compared with areas mediating judgments of physical attractiveness. A, Brain regions showing greater responses at the time of first viewing for faces of individuals that are subsequently (after speed dating) selected as a potential romantic partner (“pursued”), compared with those who were not (“rejected”). Paracingulate cortex (circled) is the only activated region that significantly independently correlates with subsequent decision in a multiple regression including all activated regions. B, Brain regions positively correlating with subjective ratings of physical attractiveness for each partner (Att). C, Overlap between brain regions related to decision and those related to attractiveness, showing substantial overlap between these variables in the paracingulate cortex. Color bars indicate t statistic. Coordinates in ICBM/MNI space.

Thursday, November 29, 2012

Cognitive and Emotional plasticity increased by Mindfulness training

Here is a fascinating study from Allen et al:

Mindfulness meditation is a set of attention-based, regulatory, and self-inquiry training regimes. Although the impact of mindfulness training (MT) on self-regulation is well established, the neural mechanisms supporting such plasticity are poorly understood. MT is thought to act through interoceptive salience and attentional control mechanisms, but until now conflicting evidence from behavioral and neural measures renders difficult distinguishing their respective roles. To resolve this question we conducted a fully randomized 6 week longitudinal trial of MT, explicitly controlling for cognitive and treatment effects with an active-control group. We measured behavioral metacognition and whole-brain blood oxygenation level-dependent (BOLD) signals using functional MRI during an affective Stroop task before and after intervention in healthy human subjects. Although both groups improved significantly on a response-inhibition task, only the MT group showed reduced affective Stroop conflict. Moreover, the MT group displayed greater dorsolateral prefrontal cortex responses during executive processing, consistent with increased recruitment of top-down mechanisms to resolve conflict. In contrast, we did not observe overall group-by-time interactions on negative affect-related reaction times or BOLD responses. However, only participants with the greatest amount of MT practice showed improvements in response inhibition and increased recruitment of dorsal anterior cingulate cortex, medial prefrontal cortex, and right anterior insula during negative valence processing. Our findings highlight the importance of active control in MT research, indicate unique neural mechanisms for progressive stages of mindfulness training, and suggest that optimal application of MT may differ depending on context, contrary to a one-size-fits-all approach.

Wednesday, November 28, 2012

Face to face dialog is different.

Jiang et al do a neat bit of work showing how modern hi-tech dialog devices fail to engage the evolved brain and body synchronization that accompanies face-to-face dialog.

Although the human brain may have evolutionarily adapted to face-to-face communication, other modes of communication, e.g., telephone and e-mail, increasingly dominate our modern daily life. This study examined the neural difference between face-to-face communication and other types of communication by simultaneously measuring two brains using a hyperscanning approach. The results showed a significant increase in the neural synchronization in the left inferior frontal cortex during a face-to-face dialog between partners but none during a back-to-back dialog, a face-to-face monologue, or a back-to-back monologue. Moreover, the neural synchronization between partners during the face-to-face dialog resulted primarily from the direct interactions between the partners, including multimodal sensory information integration and turn-taking behavior. The communicating behavior during the face-to-face dialog could be predicted accurately based on the neural synchronization level. These results suggest that face-to-face communication, particularly dialog, has special neural features that other types of communication do not have and that the neural synchronization between partners may underlie successful face-to-face communication.

Tuesday, November 27, 2012

Body-Mind dualism - effects on health.

Forstmann et al do an interesting bit of work whose results make a lot of sense:

Beliefs in mind-body dualism—that is, perceiving one’s mind and body as two distinct entities—are evident in virtually all human cultures. Despite their prevalence, surprisingly little is known about the psychological implications of holding such beliefs. In the research reported here, we investigated the relationship between dualistic beliefs and health behaviors. We theorized that holding dualistic beliefs leads people to perceive their body as a mere “shell” and, thus, to neglect it. Supporting this hypothesis, our results showed that participants who were primed with dualism reported less engagement in healthy behaviors and less positive attitudes toward such behaviors than did participants primed with physicalism. Additionally, we investigated the bidirectionality of this link. Activating health-related concepts affected participants’ subsequently reported metaphysical beliefs in mind-body dualism. A final set of studies demonstrated that participants primed with dualism make real-life decisions that may ultimately compromise their physical health (e.g., consuming unhealthy food). These findings have potential implications for health interventions.

Monday, November 26, 2012

Oxytocin nudges men to monogamy?

Scheele et al. show that oxytocin nasal spray causes married, but not single, men to keep a greater distance from attractive woman during a first encounter. They totally should do this experiment with gay married males!

In humans, interpersonal romantic attraction and the subsequent development of monogamous pair-bonds is substantially predicted by influential impressions formed during first encounters. The prosocial neuropeptide oxytocin (OXT) has been identified as a key facilitator of both interpersonal attraction and the formation of parental attachment. However, whether OXT contributes to the maintenance of monogamous bonds after they have been formed is unclear. In this randomized placebo-controlled trial, we provide the first behavioral evidence that the intranasal administration of OXT stimulates men in a monogamous relationship, but not single ones, to keep a much greater distance (∼10–15 cm) between themselves and an attractive woman during a first encounter. This avoidance of close personal proximity occurred in the physical presence of female but not male experimenters and was independent of gaze direction and whether the female experimenter or the subject was moving. We further confirmed this unexpected finding using a photograph-based approach/avoidance task that showed again that OXT only stimulated men in a monogamous relationship to approach pictures of attractive women more slowly. Importantly, these changes cannot be attributed to OXT altering the attitude of monogamous men toward attractive women or their judgments of and arousal by pictures of them. Together, our results suggest that where OXT release is stimulated during a monogamous relationship, it may additionally promote its maintenance by making men avoid signaling romantic interest to other women through close-approach behavior during social encounters. In this way, OXT may help to promote fidelity within monogamous human relationships.

Friday, November 23, 2012

Musical protolanguage hypothesis - support from congenital amusia.

Fascinating work from Thompson et al. (open access), suggesting that sensitivity to emotion in speech prosody derives from our capacity to process music, supporting the idea of an evolutionary link between musical and language domains in the brain.:

A number of evolutionary theories assume that music and language have a common origin as an emotional protolanguage that remains evident in overlapping functions and shared neural circuitry. The most basic prediction of this hypothesis is that sensitivity to emotion in speech prosody derives from the capacity to process music. We examined sensitivity to emotion in speech prosody in a sample of individuals with congenital amusia, a neurodevelopmental disorder characterized by deficits in processing acoustic and structural attributes of music. Twelve individuals with congenital amusia and 12 matched control participants judged the emotional expressions of 96 spoken phrases. Phrases were semantically neutral but prosodic cues (tone of voice) communicated each of six emotional states: happy, tender, afraid, irritated, sad, and no emotion. Congenitally amusic individuals were significantly worse than matched controls at decoding emotional prosody, with decoding rates for some emotions up to 20% lower than that of matched controls. They also reported difficulty understanding emotional prosody in their daily lives, suggesting some awareness of this deficit. The findings support speculations that music and language share mechanisms that trigger emotional responses to acoustic attributes, as predicted by theories that propose a common evolutionary link between these domains.

Thursday, November 22, 2012

Inspired by distraction.

Baird et al. do a simple experiment demonstrating how mind wandering can facilitate creative incubation, that the basement stuff that is dinking around in the absence focused effort more easily makes novel associations:

Although anecdotes that creative thoughts often arise when one is engaged in an unrelated train of thought date back thousands of years, empirical research has not yet investigated this potentially critical source of inspiration. We used an incubation paradigm to assess whether performance on validated creativity problems (the Unusual Uses Task, or UUT) can be facilitated by engaging in either a demanding task or an undemanding task that maximizes mind wandering. Compared with engaging in a demanding task, rest, or no break, engaging in an undemanding task during an incubation period led to substantial improvements in performance on previously encountered problems. Critically, the context that improved performance after the incubation period was associated with higher levels of mind wandering but not with a greater number of explicitly directed thoughts about the UUT. These data suggest that engaging in simple external tasks that allow the mind to wander may facilitate creative problem solving.

Wednesday, November 21, 2012

Unpredictable love.

There's a nice pieces in the "Gray Matter" series in the New York Times by Richard Friedman that argues that it is our evolved motivational machinery (that drives us to seek unpredictable rewards - i.e., transient reinforcement) more strenuously than predictable ones, that underlies the fickleness of love.

Shakespeare warned women that “men were deceivers ever; one foot in sea and one on shore, to one thing constant never.”
...how commonly people complain that they love someone who always disappoints them...This kind of amorous attachment is like gambling — except that the currency is affection and sex. The key is that the reward is unanticipated, which makes it particularly powerful and alluring to our brains.
Many experiments have shown, in both animals and humans, that intermittent rewards cause more activation and dopamine release in the brain's reward circuits than predictable rewards.
The brain’s reward circuit has evolved over millions of years to enable us to recognize and extract various rewards from our environment that are critical to our survival, like food and a suitable sexual mate. Unlike predictable stimuli, unanticipated stimuli can tell us things about the world that we don’t yet know. And because they serve as a signal that a big reward might be close by, it is advantageous that novel stimuli command our attention.
The article centers on the work of psychiatrist Gregory Berns:
One of the curious things that Professor Berns found was that most of his subjects couldn’t tell the difference between the predictable or unpredictable condition in which the reward was given...Since unpredictable rewards cause more dopamine release than predictable ones and more dopamine means more pleasure, one implication of this study is that people experience more pleasure with unpredictable rewards than with predictable ones — but they may not be consciously aware of this fact...Not just that, but there was essentially no relationship between the subjects’ stated preferences and the observed activity in their reward circuit. This suggests that our reward pathways may not only be activated without our recognition, but perhaps even in ways that are contrary to what we think we prefer...These data might explain, in part, the paradox of people who complain constantly about their unreliable lovers, but keep coming back to them, time and again.

Tuesday, November 20, 2012

The force of affective norms - the stranger effect

Szczurek et al. make a more distanced and structured description of an experience we all have had - being put on guard in a chat with another person if their facial expressions and body language do not appropriately mirror or complement our own:

What happens when affective displays deviate from normative expectations? In this study, participants evaluated target individuals displaying flat, incongruent, or congruent expressions seemingly in response to pictures eliciting positive, neutral, or negative affect. Relative to targets who displayed normative reactions, those who violated affective norms (affective deviants) were rated more negatively on various dimensions of social judgment. Participants also preferred greater social distance from affective deviants, reported more moral outrage in response to them, and inferred that these targets did not share their moral values. Incongruent affect resulted in more negative social judgment than did flat affect, and this relationship was moderated by stimulus valence. Finally, the relationship between targets’ affective expressions and participants’ avoidant intentions was mediated by the extent to which participants thought the targets shared their moral values. These findings demonstrate the interpersonal costs of affective deviance, revealing the pervasiveness and force of affective norms.

Monday, November 19, 2012

How a simple innate bias might guide visual learning

For years computer programmers have been trying to design algorithms that even remotely approach the ability of young infants in their first few months of life to rapidly learn to recognize complex objects and events in the their visual input, particularly events like hand movements and gaze direction. Even the most powerful probabilistic learning models, as well as connectionist and dynamical models, do not result by themselves in automatically learning about hands, detecting them, paying attention to what they are doing, and using them to make inferences and predictions. Ullman et al. develop a model that incorporates a plausible innate or early acquired bias, based on cognitive and perceptual findings, to detect “mover” events. It leads to the automatic acquisition of increasingly complex concepts and capabilities, which do not emerge without domain-specific biases. After exposure to video sequences containing people performing everyday actions, and without supervision, the model develops the capacity to locate hands in complex configurations by their appearance and by surrounding context and to detect direction of gaze. Here is their abstract:

Early in development, infants learn to solve visual problems that are highly challenging for current computational methods. We present a model that deals with two fundamental problems in which the gap between computational difficulty and infant learning is particularly striking: learning to recognize hands and learning to recognize gaze direction. The model is shown a stream of natural videos and learns without any supervision to detect human hands by appearance and by context, as well as direction of gaze, in complex natural scenes. The algorithm is guided by an empirically motivated innate mechanism—the detection of “mover” events in dynamic images, which are the events of a moving image region causing a stationary region to move or change after contact. Mover events provide an internal teaching signal, which is shown to be more effective than alternative cues and sufficient for the efficient acquisition of hand and gaze representations. The implications go beyond the specific tasks, by showing how domain-specific “proto concepts” can guide the system to acquire meaningful concepts, which are significant to the observer but statistically inconspicuous in the sensory input.

Friday, November 16, 2012

Carbs and self control.

From Molden et al. suggest the increase in self control that some studies have correlated with carbohydrate consumption is caused not by a metabolic energy boost, but rather by an increase in motivation:

Self-control is critical for achievement and well-being. However, people’s capacity for self-control is limited and becomes depleted through use. One prominent explanation for this depletion posits that self-control consumes energy through carbohydrate metabolization, which further suggests that ingesting carbohydrates improves self-control. Some evidence has supported this energy model, but because of its broad implications for efforts to improve self-control, we reevaluated the role of carbohydrates in self-control processes. In four experiments, we found that (a) exerting self-control did not increase carbohydrate metabolization, as assessed with highly precise measurements of blood glucose levels under carefully standardized conditions; (b) rinsing one’s mouth with, but not ingesting, carbohydrate solutions immediately bolstered self-control; and (c) carbohydrate rinsing did not increase blood glucose. These findings challenge metabolic explanations for the role of carbohydrates in self-control depletion; we therefore propose an alternative motivational model for these and other previously observed effects of carbohydrates on self-control.

Thursday, November 15, 2012

Self awarenss and our "spider jar"

Margit Hesthammer writes a lovely piece for the opinionator section of the NYTimes that has me thinking "I wish I had written that." It is consonant with the same core of ideas that runs through my web lectures shown in the left column of this blog, such as the "I Illusion" and "Mindstuff - a user's guide," but presented in a much more congenial and approachable fashion. (I frequently use "pandora's box" as a metaphor similar to the "spiders in a jar" used in the essay). I strongly urge you to read the whole piece, but here I excerpt a series of clips:

...behind all the containers I pour myself into from moment to moment, is my awareness of the boundless ocean of awareness itself…an unruly sea of infinite possibility, lurking in the back room…It conjures up the image Jonathan Franzen uses in his novel "The Corrections" of an impending thunderstorm: "big spiders in a little jar." Only the jar in this case is infinitely vast, the spiders correspondingly enormous. They huddle in the back room, waiting for the lid to come off...waiting to leak or seep or sneak through some hidden cat-door and flood the room I live in…With it is the chronic background anxiety that if I don't pour myself into this or that (read my book, clean the house, or at the very least think a bunch of thoughts), I'll fall into this ocean of shapelessness and lose all sense of definition. I'll be ejected from the safe confines of my predictable foreground world, where all the familiar experiences live: the sensations and tastes and textures that confirm my sense of who I am.
…when I do stray, accidentally or intentionally, into this formless background, I recall all too quickly what the foreground commotion is doing for me….It's protecting me from the intolerable experience of being a personality: a rabid consumer of ego-supplies with a curiously cruel capacity for self-awareness. A capacity that leads perversely to the realization that despite my hard-won knowledge that all my yearnings are ultimately doomed, still there will never be an end to yearning…It's protecting me from the unbearable taste of my separateness, my chronic disconnection from life, within and without. It's creating the wall of white noise that distracts me from my deep sense of meaninglessness, my feeling of being locked in and locked out at the same time - trapped on the surface of my life, nose against the glass, dimly aware that somewhere a feast is going on. Somewhere I'm not…
At some point it occurs to me that circling my jar of spiders is quite possibly the worst of it. It's so neither here nor there. I give up. Out of sheer exhaustion, I take off the lid and slide in. What else is there to do? I tell them to go ahead, eat me alive…They're only too happy to oblige. The white noise gradually subsides and they set to work, sucking the sweet, juicy marrow of hope from the bones of all my constructions. (Somewhere a feast is going on )…One after another the buildings collapse, until all hope is gone and I'm alone in the rubble….I know this place. It's flat and empty and dead. There's nowhere left to run and nothing left to hide. After a long while, I notice the quiet: bleak, but oddly relaxing. No straining, nothing to hold up. There seems to be something left of me as well, though I'd be hard pressed to give it a name. It finally dawns on me that I've made it through the switcheroo. Background has become foreground. I'm now the thing I was running from - the formless ocean of awareness itself.
My sense of an impending thunderstorm has dissolved. It was apparently a feature of life on the run. Now the spiders are all over there, where the foreground used to be. They look small and hectic from here, more like ants. Noisily milling about…Me, I'm the emptiness inside the jar, though the jar itself has vanished. I'm spacious and peaceful and vast…I like this place. As always, I resolve to remember what a relief this is…I vow to bring myself to the feast more often…As usual, I forget and get trapped outside again. Circling the jar.

Wednesday, November 14, 2012

Giving time gives you time.

In the same vein as Monday's post, Mogilner et al. note another activity that expands our subjective sense of time:

Results of four experiments reveal a counterintuitive solution to the common problem of feeling that one does not have enough time: Give some of it away. Although the objective amount of time people have cannot be increased (there are only 24 hours in a day), this research demonstrates that people’s subjective sense of time affluence can be increased. We compared spending time on other people with wasting time, spending time on oneself, and even gaining a windfall of “free” time, and we found that spending time on others increases one’s feeling of time affluence. The impact of giving time on feelings of time affluence is driven by a boosted sense of self-efficacy. Consequently, giving time makes people more willing to commit to future engagements despite their busy schedules.

Tuesday, November 13, 2012

Mental time travel and our brain's default network.

Here is some interesting material from Østby et al. on the brain basis of the quality of our remembering the past or imagining the future:

A core brain network is engaged in remembering the past and envisioning the future. This network overlaps with the so-called default-mode network, the activity of which increases when demands for focused attention are low. Because of their shared brain substrates, an intriguing hypothesis is that default-mode activity, measured at rest, is related to performance in separate attention-focused recall and imagination tasks. However, we do not know how functional connectivity of the default-mode network is related to individual differences in reconstruction of the past and imagination of the future. Here, we show that functional connectivity of the default-mode network in children and adolescents is related to the quality of past remembering and marginally to future imagination. These results corroborate previous findings of a common neuronal substrate for memory and imagination and provide evidence suggesting that mental time travel is modulated by the task-independent functional architecture of the default-mode network in the developing brain. A further analysis showed that local cortical arealization also contributed to explain recall of the past and imagination of the future, underscoring the benefits of studying both functional and structural properties to understand the brain basis for complex human cognition.

Monday, November 12, 2012

Awe is good for you…

What could most of us could do to chill out and expand our subjective sense of time? Feel a sense of awe more often! Rudd et. al. do a series of experiments illustrating that it expands our perception of time, alters decision making, and enhances well-being.

In a first experiment the authors examined whether awe would alter time perception by first manipulating whether people were induced to feel awe or happiness and then having them rate self-perceived time availability. A second experiment examined whether feeling awe, relative to feeling happiness, would alter time perception (i.e., impatience) and, in turn, willingness to donate time. A third experiment tested whether awe, compared with a neutral state, would increase participants’ choice of experiential (vs. material) goods and momentary life satisfaction, two outcomes that they hypothesized would follow from awe’s ability to expand perceptions of time. In experimental versus control subjects, awe was elicited by reliving a memory, reading a brief story, or even watching a 60-s commercial (the awe-eliciting commercial depicted people in city streets and parks encountering and interacting with vast, mentally overwhelming, and seemingly realistic images, such as waterfalls, whales, and astronauts in space.)

And, here is their abstract:

When do people feel as if they are rich in time? Not often, research and daily experience suggest. However, three experiments showed that participants who felt awe, relative to other emotions, felt they had more time available (Experiments 1 and 3) and were less impatient (Experiment 2). Participants who experienced awe also were more willing to volunteer their time to help other people (Experiment 2), more strongly preferred experiences over material products (Experiment 3), and experienced greater life satisfaction (Experiment 3). Mediation analyses revealed that these changes in decision making and well-being were due to awe’s ability to alter the subjective experience of time. Experiences of awe bring people into the present moment, and being in the present moment underlies awe’s capacity to adjust time perception, influence decisions, and make life feel more satisfying than it would otherwise.

Friday, November 09, 2012

Decreased amygdala neuroplasticity linked to early-life anxious temperament.

Some interesting work from the research groups of my University of Wisconsin colleagues Ned Kalin and Richard Davidson that suggests that altered amygdala neuroplasticity may play a role the early dispositional risk to develop anxiety and depression.:

Children with anxious temperament (AT) are particularly sensitive to new social experiences and have increased risk for developing anxiety and depression. The young rhesus monkey is optimal for studying the origin of human AT because it shares with humans the genetic, neural, and phenotypic underpinnings of complex social and emotional functioning. In vivo imaging in young monkeys demonstrated that central nucleus of the amygdala (Ce) metabolism is relatively stable across development and predicts AT. Transcriptome-wide gene expression, which reflects combined genetic and environmental influences, was assessed within the Ce. Results support a maladaptive neurodevelopmental hypothesis linking decreased amygdala neuroplasticity to early-life dispositional anxiety. For example, high AT individuals had decreased mRNA expression of neurotrophic tyrosine kinase, receptor, type 3 (NTRK3). Moreover, variation in Ce NTRK3 expression was inversely correlated with Ce metabolism and other AT-substrates. These data suggest that altered amygdala neuroplasticity may play a role the early dispositional risk to develop anxiety and depression.

Thursday, November 08, 2012

Biology of social adversity.

PNAS has done a special issue on the biology of adversity. I mention only a few of the articles here:

Ziol-Guest et al. show that low income, particularly in very early childhood (between the prenatal and second year of life), is associated with increases in early-adult hypertension, arthritis, and limitations on activities of daily living. Moreover, these relationships and particularly arthritis partially account for the associations between early childhood poverty and adult productivity as measured by adult work hours and earnings. The results suggest that the associations between early childhood poverty and these adult disease states may be immune-mediated.

McDade looks at studies of inflammatory processes involved in a wide range of chronic degenerative diseases in low income populations in the Philippines and lowland Ecuador that reveal now low levels of chronic inflammation, despite higher burdens of infectious disease, point to nutritional and microbial exposures in infancy as important determinants of inflammation in adulthood.

Hostinar et al. look at associations between early life adversity and executive function in children adopted internationally from orphanages, providing evidence that early life adversity is associated with significant reductions in executive function performance on a developmentally sensitive battery of laboratory executive fundtion tasks that measure cognitive flexibility, working memory, and inhibitory control.



Wednesday, November 07, 2012

Empathy represses analytic thought, and vice versa.

Jack et al. have performed a study (online in accepted articles in the journal Neuroimage) observing brain activity in subjects while they were engaged in social versus physical analytical contexts. When the network of neurons that allows us to empathize becomes more active, it suppresses the network used for analysis. When the analytic network is more active, ability to empathize with the human effects of our actions is repressed. Here is their abstract (a bit klutzy, but does the job), and two useful summary figures from the paper.

Two lines of evidence indicate that there exists a reciprocal inhibitory relationship between opposed brain networks. First, most attention-demanding cognitive tasks activate a stereotypical set of brain areas, known as the task-positive network and simultaneously deactivate a different set of brain regions, commonly referred to as the task negative or default mode network. Second, functional connectivity analyses show that these same opposed networks are anti-correlated in the resting state. We hypothesize that these reciprocally inhibitory effects reflect two incompatible cognitive modes, each of which is directed towards understanding the external world. Thus, engaging one mode activates one set of regions and suppresses activity in the other. We test this hypothesis by identifying two types of problem-solving task which, on the basis of prior work, have been consistently associated with the task positive and task negative regions: tasks requiring social cognition, i.e., reasoning about the mental states of other persons, and tasks requiring physical cognition, i.e., reasoning about the causal/mechanical properties of inanimate objects. Social and mechanical reasoning tasks were presented to neurologically normal participants during fMRI. Each task type was presented using both text and video clips. Regardless of presentation modality, we observed clear evidence of reciprocal suppression: social tasks deactivated regions associated with mechanical reasoning and mechanical tasks deactivated regions associated with social reasoning. These findings are not explained by self-referential processes, task engagement, mental simulation, mental time travel or external vs. internal attention, all factors previously hypothesized to explain default mode network activity. Analyses of resting state data revealed a close match between the regions our tasks identified as reciprocally inhibitory and regions of maximal anti-correlation in the resting state. These results indicate the reciprocal inhibition is not attributable to constraints inherent in the tasks, but is neural in origin. Hence, there is a physiological constraint on our ability to simultaneously engage two distinct cognitive modes. Further work is needed to more precisely characterize these opposing cognitive domains.


Tuesday, November 06, 2012

Physiological benefits of leadership - Importance of a sense of control

An edited paste-up from Sapolsky's brief review pointing to work of Sherman et al. showing that leaders feeling a sense of control have lower stress levels.

Studies on primates have shown complex relationships between social dominance, physiology, and health among primates...basal cortisol levels in nonhuman primates do not so much reflect social rank as the meaning of social rank in a particular species and social group. Similar studies in humans have been challenging, because humans belong to multiple hierarchies (for example, one can have both a low position in a corporation and also be a respected church leader), and typically the one in which they rank highest is valued most. Sherman et al. have studied a population of governmental and military leaders (with equal numbers of men and women) who had been sent to an executive training program. Subjects came from a range of midlevel ranks (e.g., officers up to the rank of colonel in the army); had been in leadership positions for an average of more than 3 y; and were presumably well-regarded, given their selection by their organization for this honor. As the key findings, compared with age, sex, and ethnicity-matched nonleader controls, and after controlling for lifestyle health factors (e.g., diet, level of exercise), leaders had substantially lower resting cortisol levels and lower levels of self-reported anxiety. Thus, within this example of hierarchical stratification, high rank carries physiological and psychological advantages.
Here is the Sherman et al. abstract:
As leaders ascend to more powerful positions in their groups, they face ever-increasing demands. As a result, there is a common perception that leaders have higher stress levels than nonleaders. However, if leaders also experience a heightened sense of control—a psychological factor known to have powerful stress-buffering effects—leadership should be associated with reduced stress levels. Using unique samples of real leaders, including military officers and government officials, we found that, compared with nonleaders, leaders had lower levels of the stress hormone cortisol and lower reports of anxiety (study 1). In study 2, leaders holding more powerful positions exhibited lower cortisol levels and less anxiety than leaders holding less powerful positions, a relationship explained significantly by their greater sense of control. Altogether, these findings reveal a clear relationship between leadership and stress, with leadership level being inversely related to stress.
Further notes from Sapolsky's review:
...although both low-cortisol and low-anxiety levels correlated with leadership, neither was correlated with the other. This supports a literature that links anxiety more closely to elevated activity of the other main branch of the stress response (i.e., the sympathetic nervous system and epinephrine secretion) than to elevated cortisol secretion...The study reported additional, subtle findings. One concerned a critical mediating psychological variable in the leaders. An extensive literature shows that for the same external stressor, subjects feel less subjectively stressed, activate less of a stress response, and are less at risk for a stress-related disease if they feel a sense of control.
Both having a greater total number of subordinates and greater levels of authority were associated with a greater sense of personal control, as well as with lower levels of cortisol and anxiety; this certainly makes intuitive sense. However, having a greater number of subordinates to manage directly was not associated with those salutary psychological and physiological end points. This lends support to the stereotypical bellyaching of the office manager who says, “It’s not so much that I’m the boss of X number of people; it’s more like I have X number of bosses.”

Monday, November 05, 2012

Oxytocin facilitates protective responses to aversive social stimuli in men..

More in the thread from last Friday's post, in this case on how our brain biases responses to positive and negative social stimuli. In spite of the fact that oxytocin reduces reactivity of the amygdala to negative social stimuli, protective responses are enhanced by a pathway that appears to recruit the insula. From Streipens et al.:

The neuropeptide oxytocin (OXT) can enhance the impact of positive social cues but may reduce that of negative ones by inhibiting amygdala activation, although it is unclear whether the latter causes blunted emotional and mnemonic responses. In two independent double-blind placebo-controlled experiments, each involving over 70 healthy male subjects, we investigated whether OXT affects modulation of startle reactivity by aversive social stimuli as well as subsequent memory for them. Intranasal OXT potentiated acoustic startle responses to negative stimuli, without affecting behavioral valence or arousal judgments, and biased subsequent memory toward negative rather than neutral items. A functional MRI analysis of this mnemonic effect revealed that, whereas OXT inhibited amygdala responses to negative stimuli, it facilitated left insula responses for subsequently remembered items and increased functional coupling between the left amygdala, left anterior insula, and left inferior frontal gyrus. Our results therefore show that OXT can potentiate the protective and mnemonic impact of aversive social information despite reducing amygdala activity, and suggest that the insula may play a role in emotional modulation of memory.

Friday, November 02, 2012

A selective magnetic zap can alter belief formation in our brains.

Dolan and collaborators continue the thread of work I mentioned first in a post last year, on our brain's rose colored glasses, how we are more likely to remember and recall pleasant than aversive stimuli. Here they show that this suppression of bad input can be blocked:

Humans form beliefs asymmetrically; we tend to discount bad news but embrace good news. This reduced impact of unfavorable information on belief updating may have important societal implications, including the generation of financial market bubbles, ill preparedness in the face of natural disasters, and overly aggressive medical decisions. Here, we selectively improved people’s tendency to incorporate bad news into their beliefs by disrupting the function of the left (but not right) inferior frontal gyrus using transcranial magnetic stimulation, thereby eliminating the engrained “good news/bad news effect.” Our results provide an instance of how selective disruption of regional human brain function paradoxically enhances the ability to incorporate unfavorable information into beliefs of vulnerability.

Thursday, November 01, 2012

Are drug effects and placebo effects additive or synergistic?

Atlas et al. make observations that suggest that drug and placebo effects are not synergistic:

Placebo treatments and opiate drugs are thought to have common effects on the opioid system and pain-related brain processes. This has created excitement about the potential for expectations to modulate drug effects themselves. If drug effects differ as a function of belief, this would challenge the assumptions underlying the standard clinical trial. We conducted two studies to directly examine the relationship between expectations and opioid analgesia. We administered the opioid agonist remifentanil to human subjects during experimental thermal pain and manipulated participants' knowledge of drug delivery using an open-hidden design. This allowed us to test drug effects, expectancy (knowledge) effects, and their interactions on pain reports and pain-related responses in the brain. Remifentanil and expectancy both reduced pain, but drug effects on pain reports and fMRI activity did not interact with expectancy. Regions associated with pain processing showed drug-induced modulation during both Open and Hidden conditions, with no differences in drug effects as a function of expectation. Instead, expectancy modulated activity in frontal cortex, with a separable time course from drug effects. These findings reveal that opiates and placebo treatments both influence clinically relevant outcomes and operate without mutual interference.