Sound processing takes motor control

摘要

The key to human cognition lies in the neocortex, a modular brain structure that is unique to mammals. Within each neocortical module, small ensembles of neurons are wired together in stereotyped patterns. Subsets of these neurons send long-range axonal projections to other modules to create systems of circuits that transform the activity of single neurons into complex behaviours such as perception, cognition and motor control. Understanding how different neocortical regions - including the motor, visual and auditory cortices - coordinate their activity is a central challenge in systems neuroscience. In this issue, Schneider et al. (page 189) describe a technically sophisticated set of experiments that unravels the mechanisms by which the motor cortex exerts control over the auditory cortex during locomotion.%为了解自己的环境，大脑的感觉区域不仅必须处理外部刺激，而且必须处理内部产生的神经信号，如运动指令。Richard Mooney及同事对运动信号影响自由行动小鼠的听觉皮层活动的突触和回路机制进行了定性。在运动、梳理和发声过程中，听觉皮层的激发性神经元会降低它们的活动，而与这种降低同时发生的是抑制性中间神经元活动的增加。通过对"次运动皮层"中的神经元（它们向听觉皮层产生长距离投射）进行光遗传学控制，便足以改变听觉皮层中由感觉激发的活动。这些发现为自主运动和外部感觉信号何以能够被整合在一起以便有可能来帮助提高听力提供了一个回路基础(circuit basis)。