抄録
Extracellular recordings from inferotemporal (IT) cortex showed that neurons for which the optimal stimuli are the same are clustered in a columnar organization. This result is consistent with the optical imaging experiments showing that a visual stimulus elicits activation of the localized spots in IT cortex. However, it is also known that the object selectivity of neighboring cells is not necessarily the same. Thus, our understanding of the columnar organization in IT cortex is only partial.
Here, we identified the spots activated by one or some of the stimuli among 18 object stimuli with optical imaging, and recorded multiple unit activities (MUAs) from these spots. For pairs of MUAs, we calculated correlation coefficients of responses to these 18 visual stimuli.
The results were as follows:(1) In upper layers, the pairs of MUAs within the spots showed high correlation coefficients supporting the view that neurons with similar object selectivity are clustered together. For the pairs in deeper layers, however, the correlation coefficients were low. Thus, the clustering of neurons with similar object selectivity may not extend down to whole cortical layer. (2) The correlation coefficients dropped down for pairs of MUAs that were separated more than 300 um across the cortical surface. This result suggests that the clustering of neurons with similar object selectivity doesn't spread over the area distant more than 300 um. In spite of these results, the reason why previous experiments showed difference in object selectivity for neighboring cells will be discussed. [Jpn J Physiol 54 Suppl:S165 (2004)]
