Kovács G, Vogels R, Orban G A
Laboratorium voor Neuro-en Psychofysiologie, KULeuven, Belgium.
J Neurosci. 1995 Mar;15(3 Pt 1):1984-97. doi: 10.1523/JNEUROSCI.15-03-01984.1995.
Humans are able to recognize shapes even when they are partially occluded by another pattern. We determined whether inferior temporal (IT) units of awake rhesus monkey remain selective for shapes that are partially occluded by other patterns. In order to link the shape selectivity to shape discrimination, we established that the monkey, like humans, can discriminate partially occluded shapes. We found that IT units are selective for shapes partially occluded by static or moving patterns. The responsiveness, however, decreased with the degree of occlusion. The shape-selective responses to the occluded shapes required longer stimulus durations compared to nonoccluded shapes, matching the better shape discrimination performance at short durations in the no-occlusion compared to the occlusion conditions. Occluder visibility had no effect for shape outlines, indicating that (amodal) shape completion, which is absent when the occluder is invisible, is not necessary for shape selectivity. These data indicate that IT neurons can, indeed, contribute to the invariance of shape perception for changes in retinal input caused by partial occlusion of the shape.
即使形状被另一种图案部分遮挡，人类也能够识别它们。我们研究了清醒恒河猴的颞下（IT）神经元对被其他图案部分遮挡的形状是否仍保持选择性。为了将形状选择性与形状辨别联系起来，我们证实猴子和人类一样，能够辨别部分遮挡的形状。我们发现，IT神经元对被静态或动态图案部分遮挡的形状具有选择性。然而，其反应性会随着遮挡程度的增加而降低。与未被遮挡的形状相比，对被遮挡形状的形状选择性反应需要更长的刺激持续时间，这与在无遮挡条件下较短持续时间内更好的形状辨别性能相匹配。遮挡物的可见性对形状轮廓没有影响，这表明当遮挡物不可见时不存在的（非模态）形状完整性，对于形状选择性来说并非必要条件。这些数据表明，IT神经元确实有助于在形状被部分遮挡导致视网膜输入变化时保持形状感知的不变性。
