Benzodiazepine effects on flicker sensitivity: role of stimulus frequency and size.
1. Benzodiazepines (BZDs) impair sensitivity to temporally modulated visual stimuli (flicker). Critical flicker-fusion frequency (CFF) is commonly used as a measure of this effect, but it only measures sensitivity to a narrow range of frequencies, usually above 25 Hz. Are other frequencies more sensitive to the effects of BZDs? 2. Flicker sensitivity at 1, 2, 4, 8, 16, and 32 Hz was measured for 1 degrees and 5 degrees stimuli before and 50 to 100 minutes after triazolam (0.25 mg), lorazepam (1.0 mg) and placebo. Drug effects on CFF were also measured. 3. Both BZDs significantly impaired overall flicker sensitivity. Triazolam produced 50% more impairment than lorazepam. CFF was significantly impaired by triazolam. BZD effects did not vary with stimulus size. 4. Significantly greater BZD-induced impairment of flicker sensitivity occurred at 16 Hz than at 1, 2, 4, or 32 Hz. 5. The magnitude of BZD effects on flicker sensitivity vary with the temporal frequency of the stimulus. BZD effects are greatest for 8-16 Hz stimuli.
Maddock
R J
RJ
Department of Psychiatry, University of California at Davis School of Medicine, Sacramento.
Casson
E J
EJ
Lott
L A
LA
Carter
C S
CS
Johnson
C A
CA
D000328:Adult; D001569:Benzodiazepines / Q000494:pharmacology*; D005260:Female; D005425:Flicker Fusion / Q000187:drug effects*; D006801:Humans; D008140:Lorazepam / Q000494:pharmacology; D008297:Male; D010775:Photic Stimulation; D014229:Triazolam / Q000494:pharmacology
D001569:Benzodiazepines; D014229:Triazolam; D008140:Lorazepam