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Investigation of sleep in aquatic and terrestrial mammals

A computer-based technique for long-term analysis of the sleep electroencephalogram (EEG) has been developed and used for studies of the effects of DSIP and related peptides on sleep in laboratory rabbits as well as for investigating the normal sleep wake patterns in Northern fur seals. A new method of in vivo voltammetric measurements of neuromediators in freely moving rats using carbon fibre electrodes was also studied. Since electrophysiological recordings are only exceptionally feasible in aquatic mammals, direct observation is mandatory for recording sleep behaviour. Recent direct observations of dolphins in a dolphinarium have indicated that rapid-eye movement sleep may be present in only very short episodes. In addition, both the dolphins and seals are easily disturbed by the presence of observers and by additional light during the night. Therefore it is mandatory to perform 24-h observations without disturbing the animals. Time-lapse video recording techniques with infrared sensitive cameras and infrared illumination were successfully in the study of sleep behaviour of large herbivores and have now applied to the study of sleep in dolphins and seals at the marine station of Utrish. A behavioural investigation of bottlenose dolphins, beluga whales and harbour porpoises was performed during the nycthemeron in addition to computer autography. Short periods of paradoxical sleep-like behaviour could be seen sometimes in dolphins and whales.

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Universität Zürich
Winterthurerstraße 190
8057 Zürich
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