Category-specific visual responses of single neurons in the human medial temporal lobe

The hippocampus, amygdala and entorhinal cortex receive convergent input fr om temporal neocortical regions specialized for processing complex visual s timuli and are important in the representation and recognition of visual im ages. Recording from 427 single neurons in the human hippocampus, entorhina l cortex and amygdala, we found a remarkable degree of category-specific fi ring of individual neurons on a trial-by-trial basis. Of the recorded neuro ns, 14% responded selectively to visual stimuli from different categories, including faces, natural scenes and houses, famous people and animals. Base d on the firing rate of individual neurons, stimulus category could be pred icted with a mean probability of error of 0.24. In the hippocampus, the pro portion of neurons responding to spatial layouts was greater than to other categories. Our data provide direct support for the role of human medial te mporal regions in the representation of different categories of visual stim uli.