Touryan Jon, Lau Brian, Dan Yang
Group in Vision Science, University of California, Berkeley, California 94720, USA.
J Neurosci. 2002 Dec 15;22(24):10811-8. doi: 10.1523/JNEUROSCI.22-24-10811.2002.
A crucial step in understanding the function of a neural circuit in visual processing is to know what stimulus features are represented in the spiking activity of the neurons. For neurons with complex, nonlinear response properties, characterization of feature representation requires measurement of their responses to a large ensemble of visual stimuli and an analysis technique that allows identification of relevant features in the stimuli. In the present study, we recorded the responses of complex cells in the primary visual cortex of the cat to spatiotemporal random-bar stimuli and applied spike-triggered correlation analysis of the stimulus ensemble. For each complex cell, we were able to isolate a small number of relevant features from a large number of null features in the random-bar stimuli. Using these features as visual stimuli, we found that each relevant feature excited the neuron effectively in isolation and contributed to the response additively when combined with other features. In contrast, the null features evoked little or no response in isolation and divisively suppressed the responses to relevant features. Thus, for each cortical complex cell, visual inputs can be decomposed into two distinct types of features (relevant and null), and additive and divisive interactions between these features may constitute the basic operations in visual cortical processing.
理解神经回路在视觉处理中功能的关键一步是要知道神经元的放电活动中表征了哪些刺激特征。对于具有复杂非线性响应特性的神经元，特征表征的刻画需要测量它们对大量视觉刺激的响应以及一种能够识别刺激中相关特征的分析技术。在本研究中，我们记录了猫初级视觉皮层中复杂细胞对时空随机条形刺激的响应，并对刺激集合应用了触发尖峰相关性分析。对于每个复杂细胞，我们能够从随机条形刺激中的大量无效特征中分离出少量相关特征。使用这些特征作为视觉刺激，我们发现每个相关特征单独作用时能有效激发神经元，与其他特征组合时则以相加的方式对响应有贡献。相比之下，无效特征单独作用时几乎不引起响应或根本不引起响应，并且以相减的方式抑制对相关特征的响应。因此，对于每个皮层复杂细胞，视觉输入可以分解为两种不同类型的特征（相关特征和无效特征），并且这些特征之间的相加和相减相互作用可能构成视觉皮层处理中的基本操作。
