1] Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California, USA. [2] Department of Physiology and Biophysics, University of Southern California, Los Angeles, California, USA. [3] Graduate Programs, Keck School of Medicine, University of Southern California, Los Angeles, California, USA. [4].
1] Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California, USA. [2] Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China. [3].
Nat Neurosci. 2014 Jun;17(6):841-50. doi: 10.1038/nn.3701. Epub 2014 Apr 20.
Cortical sensory processing is modulated by behavioral and cognitive states. How this modulation is achieved by changing synaptic circuits remains largely unknown. In awake mouse auditory cortex, we found that sensory-evoked spike responses of layer 2/3 (L2/3) excitatory cells were scaled down with preserved sensory tuning when mice transitioned from quiescence to active behaviors, including locomotion, whereas L4 and thalamic responses were unchanged. Whole-cell voltage-clamp recordings revealed that tone-evoked synaptic excitation and inhibition exhibited a robust functional balance. The change to active states caused scaling down of excitation and inhibition at approximately equal levels in L2/3 cells, but resulted in no synaptic changes in L4 cells. This lamina-specific gain control could be attributed to an enhancement of L1-mediated inhibitory tone, with L2/3 parvalbumin inhibitory neurons also being suppressed. Thus, L2/3 circuits can adjust the salience of output in accordance with momentary behavioral demands while maintaining the sensitivity and quality of sensory processing.
皮层感觉处理受到行为和认知状态的调节。这种调制是如何通过改变突触回路来实现的，在很大程度上仍然未知。在清醒小鼠的听觉皮层中，我们发现当小鼠从静止状态转变为活跃行为（包括运动）时，层 2/3（L2/3）兴奋性细胞的感觉诱发尖峰反应会随着感觉调谐而减小，而 L4 和丘脑反应则保持不变。全细胞膜片钳记录显示，音调诱发的突触兴奋和抑制表现出很强的功能平衡。向活跃状态的转变导致 L2/3 细胞中的兴奋和抑制以大致相等的水平进行缩放，但 L4 细胞中没有突触变化。这种层特异性增益控制可归因于 L1 介导的抑制性音调增强，同时 L2/3 型 parvalbumin 抑制性神经元也被抑制。因此，L2/3 回路可以根据当前的行为需求调整输出的显著性，同时保持感觉处理的敏感性和质量。
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