Balanced inhibition underlies tuning and sharpens spike timing in auditory cortex
Balanced inhibition underlies tuning and sharpens spike timing in auditory cortex
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DOI：
10.1038/nature02116
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发表时间：
2003-11-27
期刊：
影响因子：
64.8
通讯作者：
Zador, AM
中科院分区：
文献类型：
--
作者：
Wehr, M;Zador, AM
初级听觉皮层中的神经元被调谐到声音的强度和特定频率，但这种调谐的突触机制仍然不确定。抑制似乎在皮层感受野的形成中具有功能性作用，因为刺激通常抑制相似或相邻的反应（1-3），并且抑制的药理学阻断拓宽了调谐曲线（4，5）。在这里，我们使用全细胞记录在体内解开的作用，兴奋性和抑制性活动的音调诱发反应的单个神经元在听觉皮层。兴奋性和抑制性感受野覆盖几乎完全相同的领域，在经典的侧抑制模型的预测相反。因此，虽然抑制通常与兴奋一样强，但即使在感受野周围，也没有必要建立调谐。然而，抑制和兴奋发生在一个精确的和刻板的时间顺序：一个初始的弹幕兴奋性输入迅速淬灭抑制，截断尖峰反应在几个（1-4）毫秒。因此，平衡抑制可能有助于提高时间精度（6），从而减少皮层操作的随机性，而不是像以前提出的那样增加噪音（7）。
Neurons in the primary auditory cortex are tuned to the intensity and specific frequencies of sounds, but the synaptic mechanisms underlying this tuning remain uncertain. Inhibition seems to have a functional role in the formation of cortical receptive fields, because stimuli often suppress similar or neighbouring responses(1-3), and pharmacological blockade of inhibition broadens tuning curves(4,5). Here we use whole-cell recordings in vivo to disentangle the roles of excitatory and inhibitory activity in the tone-evoked responses of single neurons in the auditory cortex. The excitatory and inhibitory receptive fields cover almost exactly the same areas, in contrast to the predictions of classical lateral inhibition models. Thus, although inhibition is typically as strong as excitation, it is not necessary to establish tuning, even in the receptive field surround. However, inhibition and excitation occurred in a precise and stereotyped temporal sequence: an initial barrage of excitatory input was rapidly quenched by inhibition, truncating the spiking response within a few (1-4) milliseconds. Balanced inhibition might thus serve to increase the temporal precision(6) and thereby reduce the randomness of cortical operation, rather than to increase noise as has been proposed previously(7).