Human Cortical Regions Activated by Wide-Field Visual Motion: A H 2 15 O PET Study. Cheng, Kang, Hideaki Fujita, Iwao Kanno, Shuichi Miura, and Keiji Tanaka. Laboratory for Neural Information Processing, Frontier Research Program, Information Science Laboratory, The Institute of Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako, Saitama 351-01, Japan, and Department of Radiology and Nuclear Medicine, Research Institute for Brain and Blood Vessels-Akita, Senshu-Kubota-machi 6-10, Akita, Akita 010, Japan.
APStracts 2:0040N, 1995.
SUMMARY AND CONCLUSIONS
1. Several areas in the monkey dorsal visual pathway, including the dorsal part of the medial superior temporal area, have been found to contain cells responding to movements of a wide visual field, and are suggested to be involved in analyzing self-induced motion information. In the present study, positron emission tomography was used to localize human cortical regions responding to wide-field visual motion. Changes in regional cerebral blood flow (rCBF) were measured when subjects maintained fixation and viewed low- contrast (0.15 log unit brighter than the background) dots subtending 80 x 80 and moving either coherently or incoherently. Brain foci were localized after activity in a fixation-only paradigm was subtracted from that in the two moving-dot paradigms. 2. Both the coherent and incoherent movements significantly activated the primary/secondary visual cortex (V1/V2), and surrounding visual areas in the cuneus and superior occipital gyrus. Subtraction of images between the coherent and incoherent movements showed that the activity caused by the two types of movement was comparable in these early visual cortical regions. 3. In the lateral occipito-temporo-parietal cortex, the coherent movement specifically activated two separate areas; a posterior focus was located at the border of the right occipitotemporal gyri, and a dorsoanterior focus was located bilaterally in the temporoparietal cortex. The incoherent movement did not activate these regions. 4. A fine anatomic localization using individual magnetic resonance images was performed for the bilateral activation in the temporoparietal cortex, which was found to be located mainly in the depth of the inferior parietal lobule and a small portion of the superior and middle temporal gyri. 5. Both the coherent and incoherent movements activated a part of the superior parietal lobule located within the intraparietal sulcus (Brodmann area 7). The bilateral foci activated by the coherent movement were located more anteriorly than that activated by the incoherent movement. Subtraction images between the coherent and incoherent movements, however, did not reveal any significant rCBF increases in the superior parietal lobule. 6. Several other cortical regions known to be involved in visuospatial and visuomotor functions were also activated by the coherent movement, including the frontal eye field (Brodmann area 8), and premotor cortex (Brodmann area 6) in the frontal lobe. 7. The posteriorly located activation at the border of occipitotemporal gyri corresponds to the MT homologue reported in previous activation studies using small- to medium-size motion stimuli. The bilateral activation in the inferior parietal lobule appeared to rely on wide-field motion stimulation. 

Received 18 October 1994; accepted in final form 6 March 1995.
APS Manuscript Number J647-4.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on  3 April 1995.