Thalamic bursting and the role of timing and synchrony in thalamocortical signaling in the awake mouse

The thalamus controls transmission of sensory signals from periphery to cortex, ultimately shaping perception. Despite this significant role, dynamic thalamic gating and the consequences for downstream cortical sensory representations have not been well studied in the awake brain. We optogenetically modulated the ventro-posterior medial thalamus in the vibrissa pathway of the awake mouse, and measured spiking activity in the thalamus, and activity in primary somatosensory cortex (S1) using extracellular electrophysiology and genetically encoded voltage imaging. Thalamic hyperpolarization significantly enhanced thalamic sensory-evoked bursting, yet surprisingly the S1 cortical response was not amplified, but instead timing precision was significantly increased, spatial activation more focused, and there was an increased synchronization of cortical inhibitory neurons. A thalamocortical network model implicates the modulation of precise timing of feedforward thalamic population spiking, pr...丘脑（thalamus）负责介导外周感觉信号向大脑皮层（cortex）的传递，最终塑造感知过程。尽管其功能至关重要，但清醒大脑中的动态丘脑门控（dynamic thalamic gating）及其对下游皮层感觉表征（downstream cortical sensory representations）的影响尚未得到充分研究。本研究对清醒小鼠触须通路内的腹后内侧丘脑（ventro-posterior medial thalamus）实施光遗传学调控，并借助细胞外电生理（extracellular electrophysiology）与基因编码电压成像（genetically encoded voltage imaging）技术，同步记录了丘脑的锋电位活动以及初级躯体感觉皮层（S1）的神经活动。实验结果表明，丘脑超极化（thalamic hyperpolarization）可显著增强丘脑的感觉诱发放电爆发；但令人意外的是，初级躯体感觉皮层的响应并未被放大，反而其时间精度显著提升、空间激活更为聚焦，同时皮层抑制性神经元的同步性增强。丘脑皮层网络模型（thalamocortical network model）显示，该调控效应与前馈丘脑群体锋电位（feedforward thalamic population spiking）的精准时序调控密切相关……