Effects of two anxiolytics on distraction, habituation and dishabitiuation

Rats were engaged in a baseline activity of licking and their distraction to tone stimuli measured by an interruption in licking. Habituation, distraction to a stimulus change and dishabitiuation (the return of distraction to the original tone) were studied. Ethanol (0.4 and 0.8 g/kg) and chlordiazepoxide (7.5 mg/kg) produced significantly faster habituation, a result that cannot be attributed to changes in the baseline response rate, or to differences in the initial distraction to the tone. All groups showed 24 hr retention to the tone when they were tested in the same state in which they were habituated. There was transfer of habituation between drugged and undrugged states for rats injected with chlordiazepoxide, but rats habituated undrugged showed no retention if tested after injections of ethanol. Chlordiazepoxide impaired the specificity with which the physical parameters were coded, whereas ethanol improved the specificity of coding. Neither drug affected dishabituation.