Excitation is balanced by inhibition to cortical neurons across a wide range of conditions. To understand how this relationship is maintained, we broadly suppressed the activity of parvalbumin-expressing (PV) inhibitory neurons and asked how this affected the balance of excitation and inhibition throughout auditory cortex. Activating archaerhodopsin in PV neurons effectively suppressed them in layer 4. However, the resulting increase in excitation outweighed Arch suppression and produced a net increase in PV activity in downstream layers. Consequently, suppressing PV neurons did not reduce inhibition to principal neurons (PNs) but instead resulted in a tightly coordinated increase in both excitation and inhibition. The increase in inhibition constrained the magnitude of PN spiking responses to the increase in excitation and produced nonlinear changes in spike tuning. Excitatory-inhibitory rebalancing is mediated by strong PN-PV connectivity within and between layers and is likely engaged during normal cortical operation to ensure balance in downstream neurons.

中文翻译：

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皮质回路的兴奋和抑制的快速重新平衡

在多种条件下，通过抑制皮质神经元来平衡兴奋。为了了解这种关系是如何维持的，我们广泛抑制了表达小清蛋白（PV）的抑制性神经元的活性，并探究这如何影响整个听觉皮层的兴奋和抑制的平衡。激活 PV 神经元中的古视紫红质可有效抑制第 4 层中的古视紫红质。然而，由此产生的兴奋增加超过了古视紫红质抑制，并导致下游层中 PV 活性的净增加。因此，抑制 PV 神经元并没有减少对主神经元 (PN) 的抑制，而是导致兴奋和抑制的紧密协调增加。抑制的增加限制了 PN 尖峰响应对激励增加的幅度，并在尖峰调谐中产生非线性变化。兴奋-抑制再平衡是由层内和层间强 PN-PV 连接介导的，并且可能在正常皮层操作期间参与，以确保下游神经元的平衡。