Strengthening of Direction Selectivity by Broadly Tuned and Spatiotemporally Slightly Offset Inhibition in Mouse Visual Cortex
Strengthening of Direction Selectivity by Broadly Tuned and Spatiotemporally Slightly Offset Inhibition in Mouse Visual Cortex
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DOI：
10.1093/cercor/bhu049
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发表时间：
2015-09-01
期刊：
影响因子：
3.7
通讯作者：
Tao, Huizhong Whit
中科院分区：
文献类型：
--
作者：
Li, Ya-tang;Liu, Bao-hua;Tao, Huizhong Whit
神经元反应的方向选择性（DS）是运动检测的基础。然而，突触兴奋和抑制的整合如何有助于DS仍然没有得到很好的理解。在这里，在小鼠初级视觉皮层（V1）的体内全细胞电压钳记录显示，层4简单的细胞接收方向调谐的兴奋性输入，但几乎没有调整的抑制性输入下的漂移杆刺激。在相反方向的运动下，兴奋和抑制表现出不同的时间偏移：在首选方向上，兴奋早于抑制达到峰值，在零方向上，反之亦然。这可能是由于重叠的兴奋性和抑制性感受野之间的小的空间不匹配：兴奋性输入强度的分布是偏斜的，并且偏斜度与兴奋性输入的DS强相关，而抑制性输入强度的DS是空间对称的。神经模型显示，相对较强的抑制下空方向的运动，以及特定的时空偏移之间的兴奋和抑制，允许抑制，以提高DS的输出响应更有效地抑制空响应比首选的响应。我们的数据表明，虽然调谐兴奋性输入提供了基础DS在小鼠V1，在很大程度上untuned和时空偏移抑制有助于重要的锐化DS。
Direction selectivity (DS) of neuronal responses is fundamental for motion detection. How the integration of synaptic excitation and inhibition contributes to DS however remains not well-understood. Here, in vivo whole-cell voltage-clamp recordings in mouse primary visual cortex (V1) revealed that layer 4 simple cells received direction-tuned excitatory inputs but barely tuned inhibitory inputs under drifting-bar stimulation. Excitation and inhibition exhibited differential temporal offsets under movements of opposite directions: excitation peaked earlier than inhibition at the preferred direction, and vice versa at the null direction. This could be attributed to a small spatial mismatch between overlapping excitatory and inhibitory receptive fields: the distribution of excitatory input strengths was skewed and the skewness was strongly correlated with the DS of excitatory input, whereas that of inhibitory input strengths was spatially symmetric. Neural modeling revealed that the relatively stronger inhibition under null directional movements, as well as the specific spatial-temporal offsets between excitation and inhibition, allowed inhibition to enhance the DS of output responses by suppressing the null response more effectively than the preferred response. Our data demonstrate that while tuned excitatory input provides the basis for DS in mouse V1, the largely untuned and spatiotemporally offset inhibition contributes importantly to sharpening of DS.