Document Detail


Dual multiple-scale processing for motion in the human visual system.
MedLine Citation:
PMID:  9373668     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A number of psychophysical and physiological studies have suggested that first- and second-order motion signals are processed, at least initially, by independent pathways, and that the two pathways both consist of multiple motion-detecting channels that are each narrowly tuned to a different spatial scale (spatial frequency). However, the precise number and nature of the mechanisms that subserve first- and second-order motion perception in human vision remain both controversial and speculative. We sought to clarify this issue by conducting selective adaptation experiments, in which modulation-depth thresholds for identifying the direction of stimulus motion of first-order (luminance-defined) and second-order (contrast-defined) drifting gratings were measured both prior to and following adaptation to motion. The drift direction, spatial frequency and stimulus type (either first- or second-order) of the adaptation and test stimuli were systematically manipulated. When the adaptation and test stimuli were either both first-order gratings or both second-order gratings, robust elevations of direction-identification thresholds were found and, importantly, these aftereffects exhibited both direction-selectivity and spatial-frequency selectivity. Cross-over-adaptation effects between first- and second-order gratings were also sometimes observed, but were very weak and not spatial-frequency selective. These findings give direct support for the existence of multiple-scale processing for first- and second-order motion in the human visual system and provide additional evidence that the two varieties of motion are initially processed by independent pathways.
Authors:
S Nishida; T Ledgeway; M Edwards
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Vision research     Volume:  37     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1997-12-08     Completed Date:  1997-12-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  2685-98     Citation Subset:  IM; S    
Affiliation:
Information Science Research Laboratory, NTT Basic Research Laboratories, Kanagawa, Japan. nishida@apollo3.brl.ntt.co.jp
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Ocular / physiology
Humans
Male
Motion Perception / physiology*
Psychophysics
Sensory Thresholds / physiology
Visual Pathways / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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