Cognitive Studies: Bulletin of the Japanese Cognitive Science Society
Online ISSN : 1881-5995
Print ISSN : 1341-7924
ISSN-L : 1341-7924
Special issue on Consciousness
Locating visual awareness elicited by motion after effect in the brain using neuroimaging (SQUID) analysis
Naoyuki Osaka
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1997 Volume 4 Issue 3 Pages 3_93-3_98

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Abstract

Neural correlates of consciousness (NCC) with a special reference to visual awareness elicited by motion after effect (MAE) was investigated using neuroimaging method (SQUID). MAE is a negative after effect caused by prolonged viewing of real visual motion: After gazing at a moving pattern for a while, a stationary image will appear to move in the opposite direction. Evoked magnetic field (magnetoencephalogram; MEG) was measured when a subject observing MAE in which concentric circles appear to continuously contracting after viewing the rings moving in a single local direction (continuously expanding motion). Magnetic evoked field at latency of 182 ms was averaged from 37 cortical points over occipital, temporal and parietal areas during observing MAE after adaptation period of 5 s with low spatial frequency. MRI (Magnetic Resonance Imaging) brain image and measured dipole locus was fitted for each subject. The results clearly indicated the main unitary locus subserving visual awareness due to MAE and real motion, i.e., both illusory and real visual awareness, appear to be surrounding region over lateral occipito-temporal area in the human brain which is close to MT area.

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© 1997 Japanese Cognitive Science Society
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