Neurophysiological evidence exists that during sleep the transfer of information is blocked at thalamic levels ('sensory gating'). This was tested in a neuropsychological way, with a conditioned suppression paradigm. Presentations of an auditory stimulus during wakefulness, during sleep or during REM sleep would than differentially attenuate a previously established tone-shock association. The amount of attenuation (extinction) is reflected by the suppression of lever pressing upon presentation of the conditioned (extinguished) auditory stimulus.
After rats had learned to press a lever, they were presented tone-shock pairings to establish a tone-shock association. Than, the conditioned stimulus was presented to induce extinction, during wakefulness, during sleep and during REM sleep. Finally, the remaining strength of the tone-shock association was tested during lever pressing. Suppression, a parameter for latency, is an indicator of extinction.
The following mean latencies with SEMs in seconds were obtained: wakefulness group: 5.3 ± 1.3; sleep group: 7.4 ± 2.1 and REM sleep group: 6.1 ± 2.1.
The results showed smallest suppression in the wakefulness group, indicating extinction. Rats in the REM sleep group showed about the same suppression, while rats in the sleep group showed strongest suppression, suggesting less effective extinction. Thus, during waking and sleeping extinction takes place differentially, which suggests that the transfer of information during sleep is lower than during wakefulness. It is remarkable that the REM sleep group showed the same suppression as the wakefulness group. Nevertheless,the findings correspond in general with the predictions of sensory gating.
Poster in der Gruppe Physiologische Psychologie, Mittwoch, 31. März 1999, 17:00-19:00, Foyer 2. Stock
