Coleman Memorial Laboratory, University of California, San Francisco, San Francisco, California 94143.
Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, San Francisco, California 94143.
eNeuro. 2019 Sep 18;6(5). doi: 10.1523/ENEURO.0164-19.2019. Print 2019 Sep/Oct.
Information processing in sensory cortex is highly sensitive to nonsensory variables such as anesthetic state, arousal, and task engagement. Recent work in mouse visual cortex suggests that evoked firing rates, stimulus-response mutual information, and encoding efficiency increase when animals are engaged in movement. A disinhibitory circuit appears central to this change: inhibitory neurons expressing vasoactive intestinal peptide (VIP) are activated during movement and disinhibit pyramidal cells by suppressing other inhibitory interneurons. Paradoxically, although movement activates a similar disinhibitory circuit in auditory cortex (ACtx), most ACtx studies report reduced spiking during movement. It is unclear whether the resulting changes in spike rates result in corresponding changes in stimulus-response mutual information. We examined ACtx responses evoked by tone cloud stimuli, in awake mice of both sexes, during spontaneous movement and still conditions. VIP cells were optogenetically activated on half of trials, permitting independent analysis of the consequences of movement and VIP activation, as well as their intersection. Movement decreased stimulus-related spike rates as well as mutual information and encoding efficiency. VIP interneuron activation tended to increase stimulus-evoked spike rates but not stimulus-response mutual information, thus reducing encoding efficiency. The intersection of movement and VIP activation was largely consistent with a linear combination of these main effects: VIP activation recovered movement-induced reduction in spike rates, but not information transfer.
感觉皮层中的信息处理对非感觉变量高度敏感，例如麻醉状态、觉醒和任务参与。最近在小鼠视觉皮层的研究表明，当动物参与运动时，诱发的放电率、刺激-反应互信息和编码效率会增加。一个去抑制回路似乎是这种变化的核心：表达血管活性肠肽 (VIP) 的抑制性神经元在运动时被激活，并通过抑制其他抑制性中间神经元来去抑制锥体细胞。矛盾的是，尽管运动激活了听觉皮层 (ACtx) 中的类似去抑制回路，但大多数 ACtx 研究报告在运动期间神经元放电减少。尚不清楚神经元放电率的变化是否会导致刺激-反应互信息相应变化。我们在雄性和雌性清醒小鼠中检查了对音调云刺激的 ACtx 反应，在自发运动和静止状态下进行。在一半的试验中，通过光遗传学激活 VIP 细胞，允许独立分析运动和 VIP 激活的后果，以及它们的交集。运动降低了与刺激相关的神经元放电率以及刺激-反应互信息和编码效率。VIP 中间神经元的激活往往会增加刺激诱发的神经元放电率，但不会增加刺激-反应互信息，从而降低编码效率。运动和 VIP 激活的交集与这些主要效应的线性组合基本一致：VIP 激活恢复了运动引起的神经元放电率降低，但没有恢复信息传递。
