Nonmonotonic Synaptic Excitation and Imbalanced Inhibition Underlying Cortical Intensity Tuning
Nonmonotonic Synaptic Excitation and Imbalanced Inhibition Underlying Cortical Intensity Tuning
复制标题
DOI：
10.1016/j.neuron.2006.10.009
复制
发表时间：
2006-11
期刊：
影响因子：
16.2
通讯作者：
Guangying K. Wu;Pingyang Li;H. Tao;Li I. Zhang
中科院分区：
文献类型：
--
作者：
Guangying K. Wu;Pingyang Li;H. Tao;Li I. Zhang
强度调谐神经元具有非单调的响应级功能，可能在声强相关信息的编码中发挥重要作用。强度调节的突触机制尚不清楚。在这里，大鼠听觉皮层的体内全细胞记录显示，强度调谐的神经元，大部分聚集在一个后区，接受不平衡的音调引起的兴奋和抑制性突触输入。兴奋性输入表现出非单调的强度调谐，而随着音调强度的增加，时间延迟的抑制性输入的强度单调增加。此外，这种延迟随着强度的增加而减少，从而在高强度下增强了对激发的抑制和强度调谐的显着锐化。相比之下，非强度调谐神经元表现出共变的兴奋性和抑制性输入，它们之间的相对时间间隔随着强度的增加而稳定，导致响应水平函数单调。因此，皮层强度调节主要由兴奋性输入决定，并通过兴奋性和抑制性时间的动态控制由皮层抑制形成。
Intensity-tuned neurons, characterized by their nonmonotonic response-level function, may play important roles in the encoding of sound intensity-related information. The synaptic mechanisms underlying intensity tuning remain unclear. Here, in vivo whole-cell recordings in rat auditory cortex revealed that intensity-tuned neurons, mostly clustered in a posterior zone, receive imbalanced tone-evoked excitatory and inhibitory synaptic inputs. Excitatory inputs exhibit nonmonotonic intensity tuning, whereas with tone intensity increments, the temporally delayed inhibitory inputs increase monotonically in strength. In addition, this delay reduces with the increase of intensity, resulting in an enhanced suppression of excitation at high intensities and a significant sharpening of intensity tuning. In contrast, non-intensity-tuned neurons exhibit covaried excitatory and inhibitory inputs, and the relative time interval between them is stable with intensity increments, resulting in monotonic response-level function. Thus, cortical intensity tuning is primarily determined by excitatory inputs and shaped by cortical inhibition through a dynamic control of excitatory and inhibitory timing.