Current biology : CB
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Current biology : CB · Jun 2010
Racial bias reduces empathic sensorimotor resonance with other-race pain.
Although social psychology studies suggest that racism often manifests itself as a lack of empathy, i.e., the ability to share and comprehend others' feelings and intentions, evidence for differential empathic reactivity to the pain of same- or different-race individuals is meager. Using transcranial magnetic stimulation, we explored sensorimotor empathic brain responses in black and white individuals who exhibited implicit but not explicit ingroup preference and race-specific autonomic reactivity. We found that observing the pain of ingroup models inhibited the onlookers' corticospinal system as if they were feeling the pain. ⋯ Importantly, group-specific lack of empathic reactivity was higher in the onlookers who exhibited stronger implicit racial bias. These results indicate that human beings react empathically to the pain of stranger individuals. However, racial bias and stereotypes may change this reactivity into a group-specific lack of sensorimotor resonance.
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A central goal of modern neuroscience is to obtain a mechanistic understanding of higher brain functions under healthy and diseased conditions. Addressing this challenge requires rigorous experimental and theoretical analysis of neuronal circuits. Recent advances in optogenetics, high-resolution in vivo imaging, and reconstructions of synaptic wiring diagrams have created new opportunities to achieve this goal. ⋯ A promising vertebrate organism is the zebrafish because it is small, it is transparent at larval stages and it offers a wide range of genetic tools and advantages for neurophysiological approaches. Recent studies have highlighted the potential of zebrafish for exhaustive measurements of neuronal activity patterns, for manipulations of defined cell types in vivo and for studies of causal relationships between circuit function and behavior. In this article, we summarize background information on the zebrafish as a model in modern systems neuroscience and discuss recent results.
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Current biology : CB · Apr 2009
Development of global motion perception requires early postnatal exposure to patterned light.
The accurate representation of the motion of external objects is one of the more important tasks of the visual areas of the brain because motion by itself can provide sufficient information for discriminating visual forms and hence breaking camouflage. Whereas the analysis of the motion of single small elements can occur in primary visual cortex (V1), the perception of a common direction of global motion of some visual elements among many is supported by extrastriate cortical areas [1, 2]. Humans treated for binocular congenital cataracts afterward exhibit extreme deficits of global motion, but after monocular cataracts, the deficits are minimal [3]. ⋯ We investigated this role for early experience and its timing on kittens that were deprived of light or patterned light at different ages. Such deprivation in the first 6 weeks resulted in long-lasting (>2 yr) profound deficits of perception of global motion but no apparent effects on the perception of simple unidirectional motion. Contrary to current opinion, sensitive periods to visual deprivation in primary and extrastriate cortex may be of similar duration.
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A small subset of retinal output cells express the photopigment melanopsin, rendering them intrinsically light-sensitive. Recent work quantifies, for the first time, fundamental properties of their light response.
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Group-living animals routinely have to reach a consensus decision and choose between mutually exclusive actions in order to coordinate their activities and benefit from sociality. Theoretical models predict "democratic" rather than "despotic" decisions to be widespread in social vertebrates, because they result in lower "consensus costs"-the costs of an individual foregoing its optimal action to comply with the decision-for the group as a whole. Yet, quantification of consensus costs is entirely lacking, and empirical observations provide strong support for the occurrence of both democratic and despotic decisions in nature. ⋯ Subordinate group members followed the leader despite considerable consensus costs. Follower behavior was mediated by social ties to the leader, and where these ties were weaker, group fission was more likely to occur. Our findings highlight the importance of leader incentives and social relationships in group decision-making processes and the emergence of despotism.