There have been so many interesting things published since my last update that I decided to split the list into two emails. In this collections, we’ve got the gamut from genes to neurotransmitters to brain to behavior. Crisan (1), Long (7), and Zak (13) show that neurochemistry (with serotonin and testosterone) alter economic decision making and Gan (20) provides evidence of the role for dopamine in encoding rewards. Decision-making is further illuminated with work on the nucleus accumbens (2), the temporo-parietal junction (12), and the orbitofrontal cortex (15). The insula and its roles in both internal (18) and social (3) perceptual process are also explored. Other highlights include discussions of the neural architecture of social reasoning (9), pain (10), attention (17), and Bayesian inference (19). I also think that the implications of new work on psychopaths (8) is fascinating as we try to synthesize our intuitions about legal and moral responsibility with work on the neuropathology that underpins this disease.
1) Crişan et al. Genetic contributions of the serotonin transporter to social learning of fear and economic decision making. Social Cognitive and Affective Neuroscience (2009) vol. 4 (4) pp. 399-408
2) Cooper et al. Available alternative incentives modulate anticipatory nucleus accumbens activation. Social Cognitive and Affective Neuroscience (2009) vol. 4 (4) pp. 409-16
3) Von Dem Hagen et al. Leaving a bad taste in your mouth but not in my insula. Social Cognitive and Affective Neuroscience (2009) vol. 4 (4) pp. 379-86
4) Whitehead et al. Neural correlates of observing pretend play in which one object is represented as another. Social Cognitive and Affective Neuroscience (2009) vol. 4 (4) pp. 369-78
5) Welborn et al. Variation in orbitofrontal cortex volume: relation to sex, emotion regulation and affect. Social Cognitive and Affective Neuroscience (2009) vol. 4 (4) pp. 328-39
6) Johnson et al. Medial cortex activity, self-reflection and depression. Social Cognitive and Affective Neuroscience (2009) vol. 4 (4) pp. 313-27
7) Long et al. Serotonin shapes risky decision making in monkeys. Social Cognitive and Affective Neuroscience (2009) vol. 4 (4) pp. 346-56
8) Cima et al. Psychopaths know right from wrong but don’t care. Social Cognitive and Affective Neuroscience (2010) pp.
9) Barbey et al. An evolutionarily adaptive neural architecture for social reasoning. Trends Neurosci (2009) vol. 32 (12) pp. 603-10
10) Ploner et al. Prestimulus functional connectivity determines pain perception in humans. Proceedings of the National Academy of Sciences (2010) vol. 107 (1) pp. 355-360
11) Pompilio and Kacelnik. Context-dependent utility overrides absolute memory as a determinant of choice. Proceedings of the National Academy of Sciences (2009) pp.
12) Halko et al. Competing with peers: Mentalizing-related brain activity reflects what is at stake. Neuroimage (2009) vol. 46 (2) pp. 542-548
13) Zak et al. Testosterone administration decreases generosity in the ultimatum game. PLoS ONE (2009) vol. 4 (12) pp. e8330
14) Hobson. REM sleep and dreaming: towards a theory of protoconsciousness. Nature Reviews Neuroscience (2009) vol. 10 (11) pp. 803-13
15) Schoenbaum et al. A new perspective on the role of the orbitofrontal cortex in adaptive behaviour. Nature Reviews Neuroscience (2009) vol. 10 (12) pp. 885
16) Illes et al. Neurotalk: improving the communication of neuroscience research. Nat Rev Neurosci (2010) vol. 11 (1) pp. 61-9
17) Cohen and Maunsell. Attention improves performance primarily by reducing interneuronal correlations. Nature Neuroscience (2009) vol. 12 (12) pp. 1594-600
18) Khalsa et al. The pathways of interoceptive awareness. Nature Neuroscience (2009) vol. 12 (12) pp. 1494-6
19) Soltani and Wang. Synaptic computation underlying probabilistic inference. Nature Neuroscience (2010) vol. 13 (1) pp. 112-9
20) Gan et al. Dissociable cost and benefit encoding of future rewards by mesolimbic dopamine. Nature Neuroscience (2010) vol. 13 (1) pp. 25-7
Serotonin (5-HT) modulates emotional and cognitive functions such as fear conditioning (FC) and decision making. This study investigated the effects of a functional polymorphism in the regulatory region (5-HTTLPR) of the human 5-HT transporter (5-HTT) gene on observational FC, risk taking and susceptibility to framing in decision making under uncertainty, as well as multidimensional anxiety and autonomic control of the heart in healthy volunteers. The present results indicate that in comparison to the homozygotes for the long (l) version of 5-HTTLPR, the carriers of the short (s) version display enhanced observational FC, reduced financial risk taking and increased susceptibility to framing in economic decision making. We also found that s-carriers have increased trait anxiety due to threat in social evaluation, and ambiguous threat perception. In addition, s-carriers also show reduced autonomic control over the heart, and a pattern of reduced vagal tone and increased sympathetic activity in comparison to l-homozygotes. This is the first genetic study that identifies the association of a functional polymorphism in a key neurotransmitter-related gene with complex social-emotional and cognitive processes. The present set of results suggests an endophenotype of anxiety disorders, characterized by enhanced social learning of fear, impaired decision making and dysfunctional autonomic activity.
A reward or punishment can seem better or worse depending on what else might have happened. Little is known, however, about how neural representations of an anticipated incentive might be influenced by the available alternatives. We used event-related FMRI to investigate the activation in the nucleus accumbens (NAcc), while we varied the available alternative incentives in a monetary incentive delay task. Some task blocks included only uncertain gains and losses; others included the same uncertain gains and losses intermixed with certain gains and losses. The availability of certain gains and losses increased NAcc activation for uncertain losses and decreased the difference between uncertain gains and losses. We suggest that this pattern of activation can result from reference point changes across blocks, and that the worst available loss may serve as an important anchor for NAcc activation. These findings imply that NAcc activation represents anticipated incentive value relative to the current context of available alternative gains and losses.
Previous research has implicated regions of anterior insula/frontal operculum in processing conspecific facial expressions of disgust. It has been suggested however that there are a variety of disgust facial expression components which relate to the disgust-eliciting stimulus. The nose wrinkle is predominantly associated with irritating or offensive smells, the mouth gape and tongue extrusion with distaste and oral irritation, while a broader range of disgust elicitors including aversive interpersonal contacts and certain moral offenses are associated primarily with the upper lip curl. Using functional magnetic resonance imaging, we show that activity in the anterior insula/frontal operculum is seen only in response to canonical disgust faces, exhibiting the nose wrinkle and upper lip curl, and not in response to distaste facial expressions, exhibiting a mouth gape and tongue protrusion. Canonical disgust expressions also result in activity in brain regions linked to social cognition more broadly, including dorsal medial prefrontal cortex, posterior cingulate cortex, temporo-parietal junction and superior temporal sulcus. We interpret these differences in relation to the relative functional and communicative roles of the different disgust expressions and suggest a significant role for appraisal processes in the insula activation to facial expressions of disgust.
Observers were scanned while they watched a video of an actor using an object. Three conditions were contrasted in which the same object was used: (i) normally (e.g. using a tennis racket to hit a ball), (ii) in an unusual way (e.g. using a tennis racket to strain spaghetti), (iii) in a pretend play (e.g. playing a tennis racket like a banjo). Observing real and unusual uses of objects activated areas previously seen in studies of tool use including areas associated with a mirror system for action. Observing pretend play activated additional areas previously associated with theory of mind tasks and listening to narrative, including medial prefrontal cortex, posterior superior temporal sulcus and temporal poles. After presentation of each video, observers were asked to name the object as used in the preceding action video (e.g. racket, sieve or banjo). Naming the pretend object elicited activity in medial prefrontal cortex. These results are consistent with proposals that pretend play is a form of communicative narrative, associated with the ability to mentalize. However, this leaves open the question as to whether pretence or mentalizing is the more basic process.
Sex differences in brain structure have been examined extensively but are not completely understood, especially in relation to possible functional correlates. Our two aims in this study were to investigate sex differences in brain structure, and to investigate a possible relation between orbitofrontal cortex subregions and affective individual differences. We used tensor-based morphometry to estimate local brain volume from MPRAGE images in 117 healthy right-handed adults (58 female), age 18-40 years. We entered estimates of local brain volume as the dependent variable in a GLM, controlling for age, intelligence and whole-brain volume. Men had larger left planum temporale. Women had larger ventromedial prefrontal cortex (vmPFC), right lateral orbitofrontal (rlOFC), cerebellum, and bilateral basal ganglia and nearby white matter. vmPFC but not rlOFC volume covaried with self-reported emotion regulation strategies (reappraisal, suppression), expressivity of positive emotions (but not of negative), strength of emotional impulses, and cognitive but not somatic anxiety. vmPFC volume statistically mediated sex differences in emotion suppression. The results confirm prior reports of sex differences in orbitofrontal cortex structure, and are the first to show that normal variation in vmPFC volume is systematically related to emotion regulation and affective individual differences.
Using functional magnetic resonance imaging, we investigated neural activity associated with self-reflection in depressed [current major depressive episode (MDE)] and healthy control participants, focusing on medial cortex areas previously shown to be associated with self-reflection. Both the MDE and healthy control groups showed greater activity in anterior medial cortex (medial frontal gyrus, anterior cingulate gyrus) when cued to think about hopes and aspirations compared with duties and obligations, and greater activity in posterior medial cortex (precuneus, posterior cingulate) when cued to think about duties and obligations (Experiment 1). However, the MDE group showed less activity than controls in the same area of medial frontal cortex when self-referential cues were more ambiguous with respect to valence (Experiment 2), and less deactivation in a non-self-referential condition in both experiments. Furthermore, individual differences in rumination were positively correlated with activity in both anterior and posterior medial cortex during non-self-referential conditions. These results provide converging evidence for a dissociation of anterior and posterior medial cortex depending on the focus of self-relevant thought. They also provide neural evidence consistent with behavioral findings that depression is associated with disruption of positively valenced thoughts in response to ambiguous cues, and difficulty disengaging from self-reflection when it is appropriate to do so.
Some people love taking risks, while others avoid gambles at all costs. The neural mechanisms underlying individual variation in preference for risky or certain outcomes, however, remain poorly understood. Although behavioral pathologies associated with compulsive gambling, addiction and other psychiatric disorders implicate deficient serotonin signaling in pathological decision making, there is little experimental evidence demonstrating a link between serotonin and risky decision making, in part due to the lack of a good animal model. We used dietary rapid tryptophan depletion (RTD) to acutely lower brain serotonin in three macaques performing a simple gambling task for fluid rewards. To confirm the efficacy of RTD experiments, we measured total plasma tryptophan using high-performance liquid chromatography (HPLC) with electrochemical detection. Reducing brain serotonin synthesis decreased preference for the safe option in a gambling task. Moreover, lowering brain serotonin function significantly decreased the premium required for monkeys to switch their preference to the risky option, suggesting that diminished serotonin signaling enhances the relative subjective value of the risky option. These results implicate serotonin in risk-sensitive decision making and, further, suggest pharmacological therapies for treating pathological risk preferences in disorders such as problem gambling and addiction.
Adult psychopaths have deficits in emotional processing and inhibitory control, engage in morally inappropriate behavior, and generally fail to distinguish moral from conventional violations. These observations, together with a dominant tradition in the discipline which sees emotional processes as causally necessary for moral judgment, have led to the conclusion that psychopaths lack an understanding of moral rights and wrongs. We test an alternative explanation: psychopaths have normal understanding of right and wrong, but abnormal regulation of morally appropriate behavior. We presented psychopaths with moral dilemmas, contrasting their judgments with age- and sex-matched (i) healthy subjects and (ii) non-psychopathic, delinquents. Subjects in each group judged cases of personal harms (i.e. requiring physical contact) as less permissible than impersonal harms, even though both types of harms led to utilitarian gains. Importantly, however, psychopaths’ pattern of judgments on different dilemmas was the same as those of the other subjects. These results force a rejection of the strong hypothesis that emotional processes are causally necessary for judgments of moral dilemmas, suggesting instead that psychopaths understand the distinction between right and wrong, but do not care about such knowledge, or the consequences that ensue from their morally inappropriate behavior.
Recent progress in cognitive neuroscience highlights the involvement of the prefrontal cortex (PFC) in social cognition. Accumulating evidence demonstrates that representations within the lateral PFC enable people to coordinate their thoughts and actions with their intentions to support goal-directed social behavior. Despite the importance of this region in guiding social interactions, remarkably little is known about the functional organization and forms of social inference processed by the lateral PFC. Here, we introduce a cognitive neuroscience framework for understanding the inferential architecture of the lateral PFC, drawing upon recent theoretical developments in evolutionary psychology and emerging neuroscience evidence about how this region can orchestrate behavior on the basis of evolutionarily adaptive social norms for obligatory, prohibited and permissible courses of action.
Pain is a highly subjective experience that can be substantially influenced by differences in individual susceptibility as well as personality. How susceptibility to pain and personality translate to brain activity is largely unknown. Here, we report that the functional connectivity of two key brain areas before a sensory event reflects the susceptibility to a subsequent noxious stimulus being perceived as painful. Specifically, the prestimulus connectivity among brain areas related to the subjective perception of the body and to the modulation of pain (anterior insular cortex and brainstem, respectively) determines whether a noxious event is perceived as painful. Further, these effects of prestimulus connectivity on pain perception covary with pain-relevant personality traits. More anxious and pain-attentive individuals display weaker descending connectivity to pain modulatory brain areas. We conclude that variations in functional connectivity underlie personality-related differences in individual susceptibility to pain.
A core problem of decision theories is that although decisionmakers’ preferences depend on learning, their choices could be driven either by learned representations of the physical properties of each alternative (for instance reward sizes) or of the benefit (utility and fitness) experienced from them. Physical properties are independent of the subject’s state and context, but utility depends on both. We show that starlings’ choices are better explained by memory for context-dependent utility than by representations of the alternatives’ physical properties, even when the decisionmakers’ state is controlled and they have accurate knowledge about the options’ physical properties. Our results support the potential universality of utility-driven preference control.
Competition imposes constraints for humans who make decisions. Concomitantly, people do not only maximize their personal profit but they also try to punish unfair conspecifics. In bargaining games, subjects typically accept equal-share offers but reject unduly small offers; competition affects this balance. Here we used functional magnetic resonance imaging (fMRI) to study adjustment to competition in a bargaining 13game where subjects competed against another person for a share of the stake. For medium-sized, but not for minimum offers, competition increased the likelihood of acceptance and thus shifted behavior towards maximizing personal profits, emphasizing the importance of financial incentives. Specifically for medium- sized offers, competition was associated with increased brain activation bilaterally in the temporo-parietal junction, a region associated with mentalizing. In the right inferior frontal region, competition-related brain activation was strongest in subjects whose high acceptance rates in the standard ultimatum game hinted at a profit-oriented approach. The results suggest a network of brain areas supporting decision making under competition, with incentive-dependent mentalizing engaged when the competitor’s behavior is difficult to predict and when the stake is attractive enough to justify the effort.
How do human beings decide when to be selfish or selfless? In this study, we gave testosterone to 25 men to establish its impact on prosocial behaviors in a double-blind within-subjects design. We also confirmed participants’ testosterone levels before and after treatment through blood draws. Using the Ultimatum Game from behavioral economics, we find that men with artificially raised T, compared to themselves on placebo, were 27% less generous towards strangers with money they controlled (95% CI placebo: (1.70, 2.72); 95% CI T: (.98, 2.30)). This effect scales with a man’s level of total-, free-, and dihydro-testosterone (DHT). Men in the lowest decile of DHT were 560% more generous than men in the highest decile of DHT. We also found that men with elevated testosterone were more likely to use their own money punish those who were ungenerous toward them. Our results continue to hold after controlling for altruism. We conclude that elevated testosterone causes men to behave antisocially.
Dreaming has fascinated and mystified humankind for ages: the bizarre and evanescent qualities of dreams have invited boundless speculation about their origin, meaning and purpose. For most of the twentieth century, scientific dream theories were mainly psychological. Since the discovery of rapid eye movement (REM) sleep, the neural underpinnings of dreaming have become increasingly well understood, and it is now possible to complement the details of these brain mechanisms with a theory of consciousness that is derived from the study of dreaming. The theory advanced here emphasizes data that suggest that REM sleep may constitute a protoconscious state, providing a virtual reality model of the world that is of functional use to the development and maintenance of waking consciousness.
The orbitofrontal cortex (OFC) is crucial for changing established behaviour in the face of unexpected outcomes. This function has been attributed to the role of the OFC in response inhibition or to the idea that the OFC is a rapidly flexible associative-learning area. However, recent data contradict these accounts, and instead suggest that the OFC is crucial for signalling outcome expectancies. We suggest that this function — signalling of expected outcomes — can also explain the crucial role of the OFC in changing behaviour in the face of unexpected outcomes.
There is increasing pressure for neuroscientists to communicate their research and the societal implications of their findings to the public. Communicating science is challenging, and the transformation of communication by digital and interactive media increases the complexity of the challenge. To facilitate dialogue with the public in this new media landscape, we suggest three courses of action for the neuroscience community: a cultural shift that explicitly recognizes and rewards public outreach, the identification and development of neuroscience communication experts, and ongoing empirical research on the public communication of neuroscience.
Visual attention can improve behavioral performance by allowing observers to focus on the important information in a complex scene. Attention also typically increases the firing rates of cortical sensory neurons. Rate increases improve the signal-to-noise ratio of individual neurons, and this improvement has been assumed to underlie attention-related improvements in behavior. We recorded dozens of neurons simultaneously in visual area V4 and found that changes in single neurons accounted for only a small fraction of the improvement in the sensitivity of the population. Instead, over 80% of the attentional improvement in the population signal was caused by decreases in the correlations between the trial-to-trial fluctuations in the responses of pairs of neurons. These results suggest that the representation of sensory information in populations of neurons and the way attention affects the sensitivity of the population may only be understood by considering the interactions between neurons.
A network of cortical brain regions, including the insula and anterior cingulate cortex (ACC), has been proposed as the critical and sole substrate for interoceptive awareness. Combining lesion and pharmacological approaches in humans, we found that the insula and ACC were not critical for awareness of heartbeat sensations. Instead, this awareness was mediated by both somatosensory afferents from the skin and a network that included the insula and ACC. Together, these pathways enable the core human experience of the cardiovascular state of the body.
We propose that synapses may be the workhorse of the neuronal computations that underlie probabilistic reasoning. We built a neural circuit model for probabilistic inference in which information provided by different sensory cues must be integrated and the predictive powers of individual cues about an outcome are deduced through experience. We found that bounded synapses naturally compute, through reward-dependent plasticity, the posterior probability that a choice alternative is correct given that a cue is presented. Furthermore, a decision circuit endowed with such synapses makes choices on the basis of the summed log posterior odds and performs near-optimal cue combination. The model was validated by reproducing salient observations of, and provides insights into, a monkey experiment using a categorization task. Our model thus suggests a biophysical instantiation of the Bayesian decision rule, while predicting important deviations from it similar to the ‘base-rate neglect’ observed in human studies when alternatives have unequal prior probabilities.
Reward-predicting cues evoke activity in midbrain dopamine neurons that encodes fundamental attributes of economic value, including reward magnitude, delay and uncertainty. We found that dopamine release in rat nucleus accumbens encodes anticipated benefits, but not effort-based response costs unless they are atypically low. This neural separation of costs and benefits indicates that mesolimbic dopamine scales with the value of pending rewards, but does not encode the net utility of the action to obtain them.