Differential effects of alcohol on rod and cone temporal processing.
OBJECTIVE
One of the more reliable effects of alcohol on sensory processing is the reduction of the critical flicker fusion frequency (CFF). To gain a better understanding of the mechanisms through which alcohol influences the processing of temporal information, we explored the effects of alcohol on CFF at a high level of illumination when performance is mediated by the cones (photopic), and at a lower level when performance is dominated by the rods (low mesopic).


METHODS
Measurements of CFF were made under placebo and alcohol conditions (0.06% blood alcohol concentration) in six subjects (three men, three women). Assessments were obtained in both the rising and falling phases of absorption for both light levels at several retinal locations.


RESULTS
Alcohol was found to reduce CFF by approximately the same amount at all retinal locations for photopic viewing levels. Mesopic CFF was lower than photopic, as expected. However, it was only minimally affected by alcohol, showing only a slight decline for central viewing.


CONCLUSIONS
These results imply a selective effect on alcohol on cone function. In considering the possible mechanisms of such a selective action, we suggest that this effect may be an indirect one. That is, the poorer performance under photopic conditions may be a consequence of an alcohol-induced reduction in the inhibitory interactions that are more prevalent at photopic light levels.
Pearson
P
P
Department of Psychology, Social Science Centre, University of Western Ontario, London, Canada.
Timney
B
B
D000328:Adult; D002492:Central Nervous System Depressants / Q000097:blood / Q000494:pharmacology*; D000431:Ethanol / Q000097:blood / Q000494:pharmacology*; D005260:Female; D005425:Flicker Fusion / Q000187:drug effects*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000187:drug effects* / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects* / Q000502:physiology
D002492:Central Nervous System Depressants; D000431:Ethanol