Linked Life Data

1288011

Source:http://linkedlifedata.com/resource/pubmed/id/1288011

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1993-3-15
pubmed:abstractText
The foveal increment threshold spectral sensitivity function for a 500 msec raised cosine stimulus without spatial edges exhibits a sharp drop or "notch" in sensitivity that coincides with the wavelength of a long-wavelength adapting field. An appropriate name for this phenomenon is the "Sloan notch", after Louise Sloan, who first observed a notch in a foveal threshold spectrum. We have examined suprathreshold discriminability on both sides of the Sloan notch produced by a 6700 td, 578 nm adapting field. In a temporal two-alternative forced-choice paradigm, a suprathreshold 650 nm low-frequency "standard" stimulus was paired with low-frequency "test" stimuli, of wavelength between 600 and 670 nm and varied intensity; the observer's task was to identify the interval containing the standard. Discriminability of the test and standard typically dropped to chance for some particular test intensity, producing "indiscriminability action spectra", up to 0.7 log units above threshold. Truncated spectra (between about 530 and 560 nm) were also obtained from observers on the middle wavelength side of the Sloan notch, for a 550 nm standard. The indiscriminability action spectra of each observer were identical, up to scaling, with the observer's threshold action spectrum. Analysis of the action spectra shows that the indiscriminable stimuli are rendered equivalent at the input to a neural pathway where L- and M-cone signals converge with opposite sign. We also investigated discriminability in the spectral region containing and immediately surrounding the Sloan notch. Suprathreshold stimuli in the spectral region near the notch produce percepts that are always discriminable from 650 and 550 nm standards (and from one another), and thus we conclude that in this spectral region, perception is mediated in part by a pathway distinct from that which signals the standards. The action spectrum of this latter pathway was estimated with a variant of the discrimination procedure, and found similar to V lambda over the spectral region 575-610 nm.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0042-6989
pubmed:author
pubmed:issnType
Print
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2349-67
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Monochromatism determined at a long-wavelength/middle-wavelength cone-antagonistic locus.
pubmed:affiliation
Mahoney Institute of Neurological Sciences, University of Pennsylvania, Philadelphia 19104.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't