Carandini M, Barlow H B, O'Keefe L P, Poirson A B, Movshon J A
Howard Hughes Medical Institute, New York University, New York 10003, USA.
Philos Trans R Soc Lond B Biol Sci. 1997 Aug 29;352(1358):1149-54. doi: 10.1098/rstb.1997.0098.
We tested the hypothesis that neurons in the primary visual cortex (V1) adapt selectively to contingencies in the attributes of visual stimuli. We recorded from single neurons in macaque V1 and measured the effects of adaptation either to the sum of two gratings (compound stimulus) or to the individual gratings. According to our hypothesis, there would be a component of adaptation that is specific to the compound stimulus. In a first series of experiments, the two gratings differed in orientation. One grating had optimal orientation and the other was orthogonal to it, and therefore did not activate the neuron under study. These experiments provided evidence in favour of our hypothesis. In most cells adaptation to the compound stimulus reduced responses to the compound stimulus more than it reduced responses to the optimal grating, and the responses to the compound stimulus were reduced more by adaptation to the compound stimulus than by adaptation to the individual gratings. This suggests that a component of adaptation was specific to (and caused by) the simultaneous presence of the two orientations in the compound stimulus. To test whether V1 neurons could adapt to other contingencies in the stimulus attributes, we performed a second series of experiments, in which the component gratings were parallel but differed in spatial frequency, and were both effective in activating the neuron under study. These experiments failed to reveal convincing contingent effects of adaptation, suggesting that neurons cannot adapt equally well to all types of contingency.
初级视觉皮层（V1）中的神经元会选择性地适应视觉刺激属性中的各种情况。我们记录了猕猴V1中单个神经元的活动，并测量了适应两个光栅之和（复合刺激）或单个光栅的效果。根据我们的假设，会存在一种特定于复合刺激的适应成分。在第一系列实验中，两个光栅的方向不同。一个光栅具有最佳方向，另一个与其正交，因此不会激活所研究的神经元。这些实验为我们的假设提供了证据。在大多数细胞中，对复合刺激的适应使对复合刺激的反应减少幅度大于对最佳光栅的反应减少幅度，并且对复合刺激的反应因适应复合刺激而减少的程度大于因适应单个光栅而减少的程度。这表明存在一种适应成分，它特定于（并由）复合刺激中两个方向的同时存在所引起。为了测试V1神经元是否能适应刺激属性中的其他情况，我们进行了第二系列实验，其中组成光栅是平行的，但空间频率不同，并且两者都能有效激活所研究的神经元。这些实验未能揭示出令人信服的适应的偶然效应，这表明神经元不能同样良好地适应所有类型的情况。
