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Biomedical subjects

S L Chorover

Publications and source records attributed to S L Chorover.

5 recordsLinked to original sources

Habituation and transfer during sleep in cats.

In order to test the concept of "sleep learning", cats were exposed to habituation treatment of auditory stimuli during different stages of the sleep-waking cycle. While it was possible to demonstrate that habituation to an auditory stimulus can take place in paradoxical sleep (PS) and slow-wave sleep (SWS) as well as during periods of wakefulness, it was not always possible to demonstrate a transfer of habituation from the training period to other periods. A complete transfer of habituation occurred between the two sleep periods (PS and SWS); a partial transfer of habituation occurred between the waking period and both of the two sleep stages (PS and SWS), but only a minimal transfer of habituation was found between any one of the sleep stages and the waking period. When the cats were able to transfer the habituation, they also were able to discriminate between the habituating tone and a novel tone. The findings that only minimal transfer of habituation could occur between each of the sleep stages and the waking period do not lend support to the concept of "sleep learning".

Animals

Response plasticity in hamster olfactory bulb: peripheral and central processes.

It is a well-established fact that prolonged odor stimulation leads to marked sensory adaptation. This study demonstrates comparable electrophysiological phenomena occurring at the level of the olfactory receptor and at more central olfactory structures. Recordings of overall receptor response and of olfactory bulb unit responses were made during repeated odor stimulation. During the course of a single, continuous odor presentation response decrements were seen in the EOG (at the olfactory receptors) and were mirrored at the mitral cell layer of the bulb. When brief periods without stimulation were introduced between such odor presentations, receptor responsiveness rebounded to its original level, but mitral cell responses did not. On the basis of this dissociation it is suggested that the pattern of response decrement within the bulb represents a case of stimulus-specific habituation in a simple cortical subsystem and is well worth future investigation as a model of neural plasticity. Surgical disconnection of the olfactory bulb from one or more of its centrifugal inputs results in hyperactive, hyperresponsive mitral cells, which habituate more rapidly and show longer recovery times than do those in the intact bulb. In addition, the synchronization of such units to the inhalation cycle is markedly reduced as compared with normal preparations. These facts together suggest that the habituation of mitral cell activity does not depend on centrifugal inputs, although one or more of such inputs act indirectly in an inhibitory fashion to modulate and tune mitral cell response characteristics.

Adaptation, Physiological

Electrically-induced epileptogenesis in rabbit olfactory bulb: electrophysiological plasticity in a simple cortical system.

Sustained seizure activity can be induced in rabbit olfactory bulb by application of brief low-level current via chronically implanted micro-electrodes. Sensitivity to such stimulation is markedly augmented by prior surgical isolation of the ipsilateral or contralateral bulb. The isolated rabbit olfactory bulb apparently possesses an intrinsic system sufficient to acquire and retain altered neuronal excitability of an epileptiform kind. The preparation described here offers promise as a model for further studies of electrophysiological plasticity in a simple cortical system.

Amygdala