Defining cortical frequency tuning with recurrent excitatory circuitry
Defining cortical frequency tuning with recurrent excitatory circuitry
复制标题
DOI：
10.1038/nn2012
复制
发表时间：
2007-12-01
影响因子：
25
通讯作者：
Zhang, Li I.
中科院分区：
文献类型：
--
作者：
Liu, Bao-hua;Wu, Guangying K.;Zhang, Li I.
感觉皮质接收层的神经元从两个主要来源接收兴奋性输入：前馈丘脑皮质和循环皮层内输入。为了解决它们各自的功能作用，我们开发了一种通过竞争性激活GABA(a)而阻断GABA(B)受体来沉默皮质的新方法。在大鼠初级听觉皮层，局部皮层沉默前后同一神经元的体内全细胞记录显示，丘脑输入与总兴奋性输入占据相同的频率强度音调接受野区域，但呈现平坦的调谐曲线。相比之下，皮质内兴奋性输入的调节曲线与阈上反应的调节曲线密切匹配。这可以归因于皮质细胞在偏好频率下的选择性放大反应，由类似调谐的神经元在皮质内输入。因此，弱调谐的丘脑皮质输入决定了阈下响应范围，而皮质内输入则在很大程度上定义了调谐。这样的电路可以确保感官信息的忠实传递。
Neurons in the recipient layers of sensory cortices receive excitatory input from two major sources: the feedforward thalamocortical and recurrent intracortical inputs. To address their respective functional roles, we developed a new method for silencing cortex by competitively activating GABA(A) while blocking GABA(B) receptors. In the rat primary auditory cortex, in vivo whole-cell recording from the same neuron before and after local cortical silencing revealed that thalamic input occupied the same area of frequency-intensity tonal receptive field as the total excitatory input, but showed a flattened tuning curve. In contrast, excitatory intracortical input was sharply tuned with a tuning curve that closely matched that of suprathreshold responses. This can be attributed to a selective amplification of cortical cells' responses at preferred frequencies by intracortical inputs from similarly tuned neurons. Thus, weakly tuned thalamocortical inputs determine the subthreshold responding range, whereas intracortical inputs largely define the tuning. Such circuits may ensure a faithful conveyance of sensory information.