Proceedings of the National Academy of Sciences of the United States of America
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Proc. Natl. Acad. Sci. U.S.A. · Aug 2017
Thalamocortical synchronization during induction and emergence from propofol-induced unconsciousness.
General anesthesia (GA) is a reversible drug-induced state of altered arousal required for more than 60,000 surgical procedures each day in the United States alone. Sedation and unconsciousness under GA are associated with stereotyped electrophysiological oscillations that are thought to reflect profound disruptions of activity in neuronal circuits that mediate awareness and cognition. Computational models make specific predictions about the role of the cortex and thalamus in these oscillations. ⋯ A possible explanation is that recovery from anesthesia-induced unconsciousness follows a "boot-up" sequence actively driven by ascending arousal centers. The involvement of medial prefrontal cortex suggests that when these oscillations (alpha, delta, slow) are observed in humans, self-awareness and internal consciousness would be impaired if not abolished. These studies advance our understanding of anesthesia-induced unconsciousness and altered arousal and further establish principled neurophysiological markers of these states.
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First impressions based on facial appearance predict many important social outcomes. We investigated whether such impressions also influence the communication of scientific findings to lay audiences, a process that shapes public beliefs, opinion, and policy. ⋯ Next, we had members of the public choose real science news stories to read or watch and found that people were more likely to choose items that were paired with "interesting-looking" scientists, especially when selecting video-based communications. Finally, we had people read real science news items and found that the research was judged to be of higher quality when paired with researchers who look like "good scientists." Our findings offer insights into the social psychology of science, and indicate a source of bias in the dissemination of scientific findings to broader society.
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Malignant hyperthermia (MH) is a clinical syndrome of skeletal muscle that presents as a hypermetabolic response to volatile anesthetic gases, where susceptible persons may develop lethally high body temperatures. Genetic predisposition mainly arises from mutations on the skeletal muscle ryanodine receptor (RyR). Dantrolene is administered to alleviate MH symptoms, but its mechanism of action and its influence on the Ca2+ transients elicited by MH triggers are unknown. ⋯ Furthermore, we found in human muscle susceptible to MH that dantrolene was ineffective at reducing halothane-induced repetitive Ca2+ waves in the presence of resting levels of free [Mg2+]cyto (1 mM). However, an increase of free [Mg2+]cyto to 1.5 mM could increase the period between Ca2+ waves. These results reconcile previous contradictory reports in muscle fibers and isolated RyRs, where Mg2+ is present or absent, respectively, and define the mechanism of action of dantrolene is to increase the Mg2+ affinity of the RyR (or "stabilize" the resting state of the channel) and suggest that the accumulation of the metabolite Mg2+ from MgATP hydrolysis is required to make dantrolene administration effective in arresting an MH episode.