Document Detail

Magnetic response of human extrastriate cortex in the detection of coherent and incoherent motion.
MedLine Citation:
PMID:  10771335     Owner:  NLM     Status:  MEDLINE    
Although direction selectivity is a cardinal property of neurons in the visual motion detection system, movement of numerous elements without global direction (incoherent motion) has been shown to activate human and monkey visual systems, as does coherent motion which has global direction. We used magnetoencephalography to investigate the neural process underlying responses to these types of motions in the human extrastriate cortex. Both motions were created using a random dot kinematogram and four speeds (0, 0.6, 9.6 and 25 degrees /s). The visual stimuli were composed of two successive motions at different speeds; a coherent motion at a certain speed that changed to incoherent motion at another speed or vice versa. Magnetic responses to the change in motion consisted of a few components, the first of which was always largest. The peak latency of the first component was inversely related to the speed of the preceding motion, but for both motions it was not affected by the speed of the subsequent motion. For each subject, the estimated origin of the first component was always in the extrastriate cortex, and this changed with the speed of the preceding motion. For both motions, the location for the slower preceding motion was lateral to that for the faster preceding motion. Although the latency changes of the two motions differed, their overall response properties were markedly similar. These findings show that the speed of incoherent motion is represented in the human extrastriate cortex neurons to the same degree as coherent motion. We consider that the human visual system has a distinct neural mechanism to perceive random dots' motion even though they do not move in a specific direction as a whole.
K Lam; Y Kaneoke; A Gunji; H Yamasaki; E Matsumoto; T Naito; R Kakigi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Neuroscience     Volume:  97     ISSN:  0306-4522     ISO Abbreviation:  Neuroscience     Publication Date:  2000  
Date Detail:
Created Date:  2000-06-23     Completed Date:  2000-06-23     Revised Date:  2009-11-03    
Medline Journal Info:
Nlm Unique ID:  7605074     Medline TA:  Neuroscience     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1-10     Citation Subset:  IM; S    
Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji-cho, Okazaki, Japan.
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MeSH Terms
Brain Mapping
Motion Perception / physiology*
Photic Stimulation
Reaction Time / physiology
Visual Cortex / anatomy & histology*,  physiology*

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