FUNCTIONAL MRI OF LATERAL OCCIPITOTEMPORAL CORTEX DURING PURSUIT AND MOTION PERCEPTION

We performed functional imaging with a conventional 1.5-T magnetic res onance scanner in 9 normal subjects. We used a gradient-echo technique to examine changes in signal between periods when subjects viewed a s tationary black-and-white grating, a moving grating, and when they fol lowed a moving spot. We located image pixels with significant differen ces between the viewing conditions. In 7 subjects, these occurred in t he lateral occipitotemporal cortex, a region previously identified as a putative human homologue of the motion-sensitive middle temporal are a (MT, or V5) of monkeys. Signal intensity was greater during pursuit of the moving dot than during viewing of the moving grating with the e yes still, despite the fact that the moving grating generated more ret inal image motion. In contrast, signal intensity in striate cortex was least during pursuit of the moving dot. These findings suggest that t he lateral occipitotemporal cortex has extraretinal signals during pur suit. Such signals may include attentional input, corollary eye moveme nt information, or even a pursuit command. Extraretinal signals sugges t that tile lateral occipitotemporal cortex may contain a human homolo gue not only of MT but also of other components of the monkey V5 compl ex, such as the medial superior temporal area.