Fast cortical dynamics encode tactile grating orientation during active touch

Touch-based object recognition relies on perception of compositional tactile features like roughness, shape, and surface orientation. However, besides roughness, it remains unclear how these different tactile features are encoded by neural activity that is linked with perception. Here, we establish a cortex-dependent perceptual task in which mice discriminate tactile gratings based on orientation using only their whiskers. Multi-electrode recordings in barrel cortex reveal weak orientation tuning in average firing rates during grating exploration despite high levels of cortical activity. Just before decision, orientation information extracted from fast cortical dynamics more closely resembles concurrent psychophysical measurements than single neuron orientation tuning curves. This temporal code conveys both stimulus and choice/action-related information, suggesting that fast cortical dynamics during exploration of a tactile object both reflect the physical stimulus and impact the decision.

Methods
Go-NoGo behavior, high speed videos of whisker interactions with gratings, and multi-electrode extracellular electrophysiology

基于触摸的物体识别依赖于对粗糙度、形状、表面朝向等组合式触觉特征的感知。然而，除粗糙度外，目前仍不清楚这些不同触觉特征如何通过与感知相关的神经活动完成编码。本研究构建了一项依赖皮层活动的感知任务：小鼠仅依靠胡须，基于朝向区分触觉光栅。我们在桶皮层（barrel cortex）中开展多电极记录，结果显示：尽管皮层活动水平较高，但在探索光栅的过程中，平均放电率仅呈现较弱的朝向调谐特性。在决策即将发生前，从快速皮层动力学中提取的朝向信息，相较于单个神经元的朝向调谐曲线，更契合同步进行的心理物理测量结果。该时序编码同时传递了刺激信息与选择/动作相关信息，表明触觉物体探索过程中的快速皮层动力学，既反映了物理刺激特征，又可对决策过程产生影响。

研究方法
Go-NoGo任务（Go-NoGo task）、胡须与光栅交互的高速视频采集、以及多电极细胞外电生理记录