Relationships between the activities of color selective neurons in the inferior temporal cortex of the monkey and color discrimination behavior

在损毁或电生理研究的基础上，认为视觉信息处理腹侧流中最高的TE区(IT前部)在颜色信息加工中起着重要作用。为了研究TE神经元的颜色选择反应与知觉之间是否存在剂量联系，我们考察了猴子的颜色判断与颜色选择TE神经元的反应之间的相关性。我们在两只猴子身上训练了一个精细的颜色辨别任务，并记录了TE区颜色敏感亚区的单个神经元活动。在这项任务中，一个样本颜色刺激呈现在显示器上，猴子必须根据样本颜色与两个目标颜色的相似性进行向右或向左的扫视。根据每个神经元的颜色选择性确定两种目标颜色，使得其中一种目标颜色(首选目标颜色)比另一种…引起更强的反应颜色更多(非首选目标气味)。每个试验中的样本颜色是从CIE-XY色度图上目标颜色之间等距分布的七种颜色中选择的。首先，我们对神经元和猴子的颜色辨别能力进行了定量比较。为了计算神经元的辨别能力，我们假设神经对样本颜色集中心颜色的反应作为颜色判断的参考，通过ROC分析计算神经测量函数。然后，我们比较了基于神经测量功能的神经阈值和基于心理测量函数的行为阈值作为颜色分离，得到了80%的正确颜色判断。我们发现，在一般情况下，神经阈值低于行为阈值，尽管在一些神经元中两者具有可比性。神经阈值在颜色空间的变化与行为阈值的变化有很好的对应关系。然后我们计算了选择概率(CP)，这是神经反应的试验到试验波动和猴子的颜色判断之间相关性的定量测量。我们发现，CP平均大于0.5，这与这些TE神经元的活动与猴子的颜色判断呈正相关的预期是一致的。最后，我们发现颜色辨别的神经阈值与CP之间的相关性很小。这表明，具有不同颜色敏感性的大量颜色选择性TE神经元而不是具有特别高颜色敏感性的特定神经元子集有助于颜色辨别性能。较少

On the basis of lesion or electrophysiological studies, it is suggested that area TE (anterior part of IT), which is the highest area in the ventral stream of visual information processing, plays an important role for information processing of color.To study whether there exists dose link between color selective responses of TE neurons and perception, we examined the correlation between monkey's color judgment and responses of color selective TE neurons. We trained a fine color discrimination task in two monkeys and recorded single neuron activities from the color-sensitive sub-region in area TE. In this task, a sample color stimulus was presented at the confer of the display, and the monkey had to make either the rightward or leftward saccade depending on the similarity of the sample color to the two target colors. Two target colors were determined based on the color selectivity of each neuron such that one target color (preferred target color) evoked stronger response than the other … More color (non-preferred target odor). Sample color in each trial was chosen from seven colors equally spaced between the target colors on the CIE-xy chromaticity diagram. First, we quantitatively compared the color discrimination abilities of neurons and the monkeys. To calculate the discrimination ability of the neuron, we computed neurometric function by ROC analysis based on the assumption that neural responses to the center color of sample color set are used as the reference for the color judgment. We then compared neural threshold based on the neurometric function and behavioral threshold based on the psychometric function as the color separation which yielded 80% correct color judgments. We found that in general neural threshold was lower than the behavioral threshold although in some neurons both are comparable. Variation of the neural threshold across the color space corresponded well with that of behavioral threshold. We then calculated the Choice Probability (CP) that is a quantitative measure of correlation between trial-to-trial fluctuation of neural responses and the monkey's color judgment. We found that CP are on average larger than 0.5 and this is consistent with the expectation that the activities of these TE neurons positively correlate with the monkey's color judgment. Finally, we found that there is little correlation between the neural threshold for color discrimination and CP. This suggests that a large population of color selective TE neurons having various color sensitivity rather than a specific subset of neurons with particularly high color sensitivity contribute to the color discrimination performance. Less