Document Detail

Orientation bandwidths are invariant across spatiotemporal frequency after isotropic components are removed.
MedLine Citation:
PMID:  20053108     Owner:  NLM     Status:  MEDLINE    
It is well established that mammalian visual cortex possesses a large proportion of orientation-selective neurons. Attempts to measure the bandwidth of these mechanisms psychophysically have yielded highly variable results ( approximately 6 degrees -180 degrees ). Two stimulus factors have been proposed to account for this variability: spatial and temporal frequency; with several studies indicating broader bandwidths at low spatial and high temporal frequencies. We estimated orientation bandwidths using a classic overlay masking paradigm across a range of spatiotemporal frequencies (0.5, 2, and 8 c.p.d.; 1.6 and 12.5 Hz) with target and mask presented either monoptically or dichoptically. A standard three-parameter Gaussian model (amplitude and width, mean fixed at 0 degrees ) confirms that bandwidths generally increase at low spatial and high temporal frequencies. When incorporating an additional orientation-untuned (isotropic) amplitude component, however, we find that not only are the amplitudes of isotropic and orientation-tuned components highly dependent upon stimulus spatiotemporal frequency, but orientation bandwidths are highly invariant ( approximately 30 degrees half width half amplitude). These results suggest that previously reported spatiotemporally contingent bandwidth effects may have confounded bandwidth with isotropic (so-called cross-orientation) masking. Interestingly, the magnitudes of all monoptically derived parameter estimates were found to transfer dichoptically suggesting a cortical locus for both isotropic and orientation-tuned masking.
John Cass; Sjoerd Stuit; Peter Bex; David Alais
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-11-23
Journal Detail:
Title:  Journal of vision     Volume:  9     ISSN:  1534-7362     ISO Abbreviation:  J Vis     Publication Date:  2009  
Date Detail:
Created Date:  2010-01-07     Completed Date:  2010-03-31     Revised Date:  2014-09-15    
Medline Journal Info:
Nlm Unique ID:  101147197     Medline TA:  J Vis     Country:  United States    
Other Details:
Languages:  eng     Pagination:  17.1-14     Citation Subset:  IM    
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MeSH Terms
Adaptation, Physiological
Neurons / physiology*
Perceptual Masking
Photic Stimulation
Sensory Thresholds
Space Perception*
Time Factors
Vision, Binocular
Vision, Monocular
Visual Cortex / physiology*
Grant Support
R01 EY 0119281/EY/NEI NIH HHS; R01 EY018664/EY/NEI NIH HHS; R01 EY018664/EY/NEI NIH HHS; R01 EY018664-02/EY/NEI NIH HHS; R01 EY019281/EY/NEI NIH HHS

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