title: Effect of hemifield stimulation on simultaneous steady-state pattern reversal electroretinogram and visual evoked response.
abstract: Steady-state pattern reversal electroretinograms (PERG) and pattern reversal visual evoked responses (PVER) were recorded simultaneously in 4 normal subjects using hemifield stimulation of the upper/lower and nasal/temporal conditions with 95 and 60% stimulus contrasts. A square-wave checker-board pattern (check size 40 min of arc) was used. The temporal frequency (reversal rate) was 6 Hz (12 reversals/s). With nasal/temporal hemifield stimulation, neither the PERG nor the PVER amplitudes differed significantly with either stimulus contrast. With the upper/lower hemifield stimulation, PERG amplitudes were not significantly different; PVER showed a significantly larger amplitude for lower than for upper hemifield stimulation with both contrasts (ANOVA test: p = 0.0064, 95% contrast; p = 0.0018, 60% contrast). PVER amplitudes recorded with lower hemifield stimulation were 2.05 and 2.63 times larger than those elicited with upper hemifield stimulation, for the 95 and 60% contrasts, respectively. The difference in response to the upper/lower hemifield stimulation, observed only in PVER, suggests that the lower stimulus field dominancy may be processed in a visual pathway proximal to the retinal level.
authors.affiliation: Department of Ophthalmology, Harvard Medical School, Boston, Mass.
authors.forename: O
authors.initials: O
authors.lastname: Katsumi
authors.forename: S
authors.initials: S
authors.lastname: Tetsuka
authors.forename: M C
authors.initials: MC
authors.lastname: Mehta
authors.forename: H
authors.initials: H
authors.lastname: Tetsuka
authors.forename: T
authors.initials: T
authors.lastname: Hirose
mesh_terms: D000328:Adult; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D012684:Sensory Thresholds; D014794:Visual Fields / Q000502:physiology*