Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
J Neurosci. 2012 Oct 24;32(43):15205-15. doi: 10.1523/JNEUROSCI.1019-12.2012.
During waking behavior, animals adapt their state of arousal in response to environmental pressures. Sensory processing is regulated in aroused states, and several lines of evidence imply that this is mediated at least partly by the serotonergic system. However, there is little information directly showing that serotonergic function is required for state-dependent modulation of sensory processing. Here we find that zebrafish larvae can maintain a short-term state of arousal during which neurons in the dorsal raphe modulate sensory responsiveness to behaviorally relevant visual cues. After a brief exposure to water flow, larvae show elevated activity and heightened sensitivity to perceived motion. Calcium imaging of neuronal activity after flow revealed increased activity in serotonergic neurons of the dorsal raphe. Genetic ablation of these neurons abolished the increase in visual sensitivity during arousal without affecting baseline visual function or locomotor activity. We traced projections from the dorsal raphe to a major visual area, the optic tectum. Laser ablation of the tectum demonstrated that this structure, like the dorsal raphe, is required for improved visual sensitivity during arousal. These findings reveal that serotonergic neurons of the dorsal raphe have a state-dependent role in matching sensory responsiveness to behavioral context.
在清醒行为中，动物会根据环境压力调整其觉醒状态。在觉醒状态下，感官处理受到调节，有几条证据表明，至少部分是由 5-羟色胺能系统介导的。然而，直接表明 5-羟色胺能功能是感觉处理的状态依赖性调节所必需的信息很少。在这里，我们发现斑马鱼幼虫可以在短时间内保持觉醒状态，在此期间中脑导水管周围灰质中的神经元调节对行为相关视觉线索的感觉反应性。在短暂暴露于水流后，幼虫表现出更高的活动水平和对感知运动的更高敏感性。在水流后对神经元活动进行钙成像显示，中脑导水管周围灰质中的 5-羟色胺能神经元活性增加。这些神经元的遗传消融消除了觉醒期间视觉敏感性的增加，而不影响基线视觉功能或运动活动。我们追踪了中脑导水管周围灰质到主要视觉区域视顶盖的投射。顶盖的激光消融表明，该结构与中脑导水管周围灰质一样，对于觉醒期间提高视觉敏感性是必需的。这些发现表明，中脑导水管周围灰质中的 5-羟色胺能神经元在将感觉反应性与行为背景相匹配方面具有状态依赖性作用。
