Anterior inferotemporal neurons of monkeys engaged in object recognition can be highly sensitive to object retinal position
Anterior inferotemporal neurons of monkeys engaged in object recognition can be highly sensitive to object retinal position
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DOI：
10.1152/jn.00358.2002
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发表时间：
2003-06-01
影响因子：
2.5
通讯作者：
Maunsell, JHR
中科院分区：
文献类型：
--
作者：
DiCarlo, JJ;Maunsell, JHR
视觉对象识别在计算上很困难，因为对象的位置、距离、姿势或设置的变化可能会导致它在每次遇到时产生不同的视网膜图像。为了稳健地识别物体，灵长类动物的大脑必须具有补偿这些变化的机制。尽管人们对这些机制知之甚少，但人们认为它们详细阐述了颞下皮层中的神经元表征，这些神经元表征对物体形式敏感，但对其他图像变化基本不变。这项研究检验了物体位置变化引起的图像变化的假设。我们研究了小（0.6度宽）视觉形式的视网膜位置的微小差异（+/-1.5度）对经过训练识别这些形式的猴子的行为以及在该行为期间收集的146个前IT（AIT）神经元的反应的影响。行为准确性和速度在很大程度上不受位置的这些微小变化的影响。与之前的研究一致，许多 AIT 回复对表格都有高度选择性。然而，AIT 反应对视网膜位置的敏感性远高于根据其报告的感受野 (RF) 大小预测的敏感性。中位 AIT 神经元在注视中心 +/-1.5 度范围内的位置之间表现出类似 60% 的响应下降，并且 52% 的神经元对这些位置中的一个或多个没有响应。与之前的研究一致，每个神经元的目标偏好排序在位置变化时基本上不受影响。尽管我们尚未确定观察 AIT 反应中这种明显位置敏感性所需的条件，但我们排除了空间频率内容、眼球运动和未能包含 RF 中心的影响。为了使这一观察结果与之前的研究相一致，我们假设 AIT 位置敏感性强烈依赖于物体大小，或者位置敏感性通过固定视网膜位置的广泛视觉体验或侧翼干扰物的存在而增强。
Visual object recognition is computationally difficult because changes in an object's position, distance, pose, or setting may cause it to produce a different retinal image on each encounter. To robustly recognize objects, the primate brain must have mechanisms to compensate for these variations. Although these mechanisms are poorly understood, it is thought that they elaborate neuronal representations in the inferotemporal cortex that are sensitive to object form but substantially invariant to other image variations. This study examines this hypothesis for image variation resulting from changes in object position. We studied the effect of small differences (+/-1.5degrees) in the retinal position of small (0.6degrees wide) visual forms on both the behavior of monkeys trained to identify those forms and the responses of 146 anterior IT (AIT) neurons collected during that behavior. Behavioral accuracy and speed were largely unaffected by these small changes in position. Consistent with previous studies, many AIT responses were highly selective for the forms. However, AIT responses showed far greater sensitivity to retinal position than predicted from their reported receptive field (RF) sizes. The median AIT neuron showed a similar to60% response decrease between positions within +/-1.5degrees of the center of gaze, and 52% of neurons were unresponsive to one or more of these positions. Consistent with previous studies, each neuron's rank order of target preferences was largely unaffected across position changes. Although we have not yet determined the conditions necessary to observe this marked position sensitivity in AIT responses, we rule out effects of spatial-frequency content, eye movements, and failures to include the RF center. To reconcile this observation with previous studies, we hypothesize that either AIT position sensitivity strongly depends on object size or that position sensitivity is sharpened by extensive visual experience at fixed retinal positions or by the presence of flanking distractors.