Pupillary responses in normal subjects following auditory stimulation.
To clarify pupillary responses of humans following auditory stimuli, we studied both eyes of 61 normal subjects using a computed pupillograph. Unilateral auditory stimulation elicited pupillary dilatation in all cases. Pupillary responses were classified according to duration as being either "long" or "short". The duration of dilatation was 1530 +/- 320 ms (mean +/- SD) in the long-lasting group (n = 45) and 850 +/- 250 ms in the short-lasting group (n = 16). The latency time for dilatation was 460 +/- 80 ms. Both eyes of each subject showed the same response. Two drops of 10% guanethidine, a sympathetic blocking agent, were applied to one eye of 3 subjects. Although the early phase of dilatation was barely affected, the late phase was inhibited, as seen in long-lasting dilatation. The short-lasting response was unaffected. We conclude that the long-lasting response consists of an early pupillary dilatation due to inhibition of parasympathetic nervous activity and a late dilatation due to excitation of sympathetic activity. The short-lasting response is produced only by inhibition of the parasympathetic component.
Hirano
T
T
Department of Otorhinolaryngology, Faculty of Medicine, Kyushu University, Fukuoka 812, Japan.
Inoue
H
H
Uemura
T
T
Matsunaga
K
K
D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D000368:Aged; D004108:Dilatation, Pathologic / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012025:Reflex, Pupillary / Q000502:physiology*