In:
Visual Neuroscience, Cambridge University Press (CUP), Vol. 14, No. 3 ( 1997-05), p. 577-587
Abstract:
We recorded visual evoked potentials in response to square-wave contrast-reversal checkerboards undergoing a transition in the mean contrast level. Checkerboards were modulated at 4.22 Hz (8.45-Hz reversal rate). After each set of 16 cycles of reversals, stimulus contrast abruptly switched between a “high” contrast level (0.06 to 1.0) to a “low” contrast level (0.03 to 0.5). Higher contrasts attenuated responses to lower contrasts by up to a factor of 2 during the period immediately following the contrast change. Contrast-response functions derived from the initial second following a conditioning contrast shifted by a factor of 2–4 along the contrast axis. For low-contrast stimuli, response phase was an advancing function of the contrast level in the immediately preceding second. For high-contrast stimuli, response phase was independent of the prior contrast history. Steady stimulation for periods as long as 1 min produced only minor effects on response amplitude, and no detectable effects on response phase. These observations delineate the dynamics of a contrast gain control in human vision.
Type of Medium:
Online Resource
ISSN:
0952-5238
,
1469-8714
DOI:
10.1017/S0952523800012232
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
1997
detail.hit.zdb_id:
1489922-X
SSG:
12
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