Bilateral integration in somatosensory cortex is controlled by behavioral relevance

Sensory perception naturally requires processing stimuli from both sides of the body. Yet, how neurons bind stimulus features across the hemispheres to create a unified perceptual experience remains unknown. To address this question, we performed large-scale recordings from neurons in both somatosensory cortices (S1) while mice shared information between their hemispheres and discriminated between two categories of bilateral stimuli. When expert mice touched stimuli associated with reward, they moved their whiskers with greater bilateral symmetry. During this period, synchronous spiking and enhanced spike-field coupling emerged between the hemispheres. This coordinated activity was absent in stimulus-matched naïve animals, indicating that interhemispheric (IH) binding was controlled by a goal-directed, internal process. In S1 neurons, the addition of ipsilateral touch primarily facilitated the contralateral, principal whisker response. This facilitation primarily emerged for reward-associated stimuli and was lost on trials where expert mice failed to respond. Taken together, these results reveal a novel state-dependent logic underlying bilateral integration in S1, where stimulus binding and facilitation are controlled by behavioral relevance.感知觉天然需要处理来自躯体双侧的刺激。然而，神经元如何跨大脑半球整合刺激特征以形成统一的感知体验，目前仍未可知。为解答这一问题，我们对双侧躯体感觉皮层（somatosensory cortices, S1）内的神经元开展了大规模记录实验，实验中小鼠可在大脑半球间传递信息，并对两类双侧刺激进行辨别。当经训练的熟练小鼠触碰与奖励相关的刺激时，其胡须运动的双侧对称性显著提升。在此期间，双侧半球间出现了同步锋电位发放与增强的锋电位-场电位耦合现象。而在刺激匹配的未训练动物中，这种协同活动并未出现，这表明半球间（interhemispheric, IH）绑定受目标导向的内在过程调控。在躯体感觉皮层神经元中，同侧触碰主要易化了对侧主胡须的响应。这类易化效应主要出现在与奖励相关的刺激情境中，且在熟练小鼠未作出正确反应的试次中消失。综上，本研究结果揭示了躯体感觉皮层内双侧整合的新型状态依赖逻辑：刺激绑定与易化效应受行为相关性调控。