Valdez André B, Papesh Megan H, Treiman David M, Smith Kris A, Goldinger Stephen D, Steinmetz Peter N
Department of Neurology, Barrow Neurological Institute, Phoenix, Arizona 85013.
Department of Psychology, Louisiana State University, Baton Rouge, Louisiana 70803.
J Neurosci. 2015 Apr 1;35(13):5180-6. doi: 10.1523/JNEUROSCI.1958-14.2015.
It remains unclear how single neurons in the human brain represent whole-object visual stimuli. While recordings in both human and nonhuman primates have shown distributed representations of objects (many neurons encoding multiple objects), recordings of single neurons in the human medial temporal lobe, taken as subjects' discriminated objects during multiple presentations, have shown gnostic representations (single neurons encoding one object). Because some studies suggest that repeated viewing may enhance neural selectivity for objects, we had human subjects discriminate objects in a single, more naturalistic viewing session. We found that, across 432 well isolated neurons recorded in the hippocampus and amygdala, the average fraction of objects encoded was 26%. We also found that more neurons encoded several objects versus only one object in the hippocampus (28 vs 18%, p < 0.001) and in the amygdala (30 vs 19%, p < 0.001). Thus, during realistic viewing experiences, typical neurons in the human medial temporal lobe code for a considerable range of objects, across multiple semantic categories.
目前尚不清楚人类大脑中的单个神经元如何表征整体物体视觉刺激。虽然对人类和非人类灵长类动物的记录都显示了物体的分布式表征（许多神经元编码多个物体），但在人类内侧颞叶进行的单个神经元记录（在多次呈现过程中让受试者辨别物体）显示了认知表征（单个神经元编码一个物体）。由于一些研究表明，重复观看可能会增强神经元对物体的选择性，因此我们让人类受试者在单次更自然的观看过程中辨别物体。我们发现，在海马体和杏仁核中记录的432个分离良好的神经元中，编码物体的平均比例为26%。我们还发现，在海马体中编码多个物体的神经元比仅编码一个物体的神经元更多（28%对18%，p<0.001），在杏仁核中也是如此（30%对19%，p<0.001）。因此，在现实的观看体验中，人类内侧颞叶中的典型神经元会对多个语义类别的相当多物体进行编码。
