Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, California, United States of America.
Neuroscience Graduate Program, University of Southern California, Los Angeles, California, United States of America.
PLoS Biol. 2020 Nov 3;18(11):e3000882. doi: 10.1371/journal.pbio.3000882. eCollection 2020 Nov.
During active tactile exploration, the dynamic patterns of touch are transduced to electrical signals and transformed by the brain into a mental representation of the object under investigation. This transformation from sensation to perception is thought to be a major function of the mammalian cortex. In primary somatosensory cortex (S1) of mice, layer 5 (L5) pyramidal neurons are major outputs to downstream areas that influence perception, decision-making, and motor control. We investigated self-motion and touch representations in L5 of S1 with juxtacellular loose-seal patch recordings of optogenetically identified excitatory neurons. We found that during rhythmic whisker movement, 54 of 115 active neurons (47%) represented self-motion. This population was significantly more modulated by whisker angle than by phase. Upon active touch, a distinct pattern of activity was evoked across L5, which represented the whisker angle at the time of touch. Object location was decodable with submillimeter precision from the touch-evoked spike counts of a randomly sampled handful of these neurons. These representations of whisker angle during self-motion and touch were independent, both in the selection of which neurons were active and in the angle-tuning preference of coactive neurons. Thus, the output of S1 transiently shifts from a representation of self-motion to an independent representation of explored object location during active touch.
在主动触觉探索过程中，动态触摸模式被转化为电信号，并由大脑转化为被研究对象的心理表象。这种从感觉到感知的转变被认为是哺乳动物皮层的主要功能之一。在小鼠的初级体感皮层（S1）中，第 5 层（L5）的锥体神经元是向影响感知、决策和运动控制的下游区域的主要输出。我们通过光遗传学鉴定的兴奋性神经元的细胞外松散密封贴片记录，研究了 L5 中的自我运动和触摸表示。我们发现，在有节奏的胡须运动期间，115 个活跃神经元中有 54 个（47%）代表自我运动。该群体的调制显著受胡须角度影响，而非相位。在主动触摸时，整个 L5 都会诱发一种独特的活动模式，代表触摸时的胡须角度。从随机采样的这些神经元中的一小部分的触摸诱发的尖峰计数中，可以以亚毫米的精度解码物体位置。在自我运动和触摸期间，这些胡须角度的表示是独立的，无论是活跃神经元的选择还是共活跃神经元的角度调谐偏好都是如此。因此，在主动触摸期间，S1 的输出会从自我运动的表示临时切换到被探索物体位置的独立表示。
