Magnetically recorded oscillatory responses to luminance stimulation in man.
Fast-frequency (ca. 100-110 Hz) oscillatory potentials superimposed on waves N2 and P2 of conventional broad-band VEP were magnetically recorded in man from occipital locations in response to monocular transient flash stimulation with full-field flashes (3.5 cd.s.m-2 intensity) and in spots (1, 1.5, or 2.0 cm in diameter). These oscillations proved replicable between- and within-subject and were phase-locked to retinal oscillatory potentials, with maximum correlation at approximately 35 ms and mean delay (as measured between the first measurable peaks) of 27.4 +/- 1.6 ms. When stimuli were in spots at increasing eccentricity (5, 15, or 25 degrees) from foveal fixation, broad-band VEP were recorded regardless of diameter and eccentricity of spot, whereas oscillatory responses were not detectable at eccentricity of, or greater than, 15 degrees. This observation suggests that broad-band VEP and the oscillatory response are generated by (partly) distinct neuronal populations and/or functional arrangements and that there is some functional connection between cortical oscillatory responses and stimulus-related events triggered in central retina.
Lopez
L
L
Institute for Advanced Biomedical Technologies, University of Chieti, Italy.
Sannita
W G
WG
D000328:Adult; D001921:Brain / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D012160:Retina / Q000502:physiology*