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.

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.

Olfactory bulb units: activity correlated with inhalation cycles and odor quality.

Single olfactory bulb units were studied in two macrosmatic species of rodents under conditions intended to preserve the cyclical stimulation which normally accompanies nasal breathing. Patterns of unit activity related to the inhalation cycle were observed in all animals, often in the absence of specific stimuli, and could not be explained in simple mechanical terms. Distinctive changes in these patterns occurred in response to certain odors, and were generally independent of changes in the overall firing frequency.

Metacontrast: its relation to evoked potentials.

Electrophysiological correlates of metacontrast were studied by means of averaged evoked potentials recorded from the scalp in man. Under conditions in which the brightness of the first of two successive stimuli appears diminished there is no accompanying attenuation of the evoked potentials to that stimulus. The results suggest that the amplitude and latency of evoked potentials correlate with stimulus intensity but not with brightness.

LATERAL HYPOTHALAMIC STIMULATION IN SATIATED RATS: T-MAZE LEARNING FOR FOOD.

It is well known that electrical stimulation in portions of the lateral hypothalamic area is positively reinforcing and induces eating in satiated rats. We have found that continuous stimulation of this kind can also motivate satiated and previously untrained rats to learn the location of food in a T-maze. Efficient acquisition and reversal of discriminations for food indicate that lateral hypothalamic stimulation exerts motivational effects which are functionally equivalent to those of food deprivation.

CAUDATE NUCLEUS LESIONS: BEHAVIORAL EFFECTS IN THE RAT.

Bilateral lesions within the caudate nucleus led to a marked impairmentc on acquistion and retention tion of a spatial alternation habit but produced no deficit in Hebb-Williams maze performance. Conversely, subtotal bilateral lesions of posterior cortex produced no significant deficit on the alternation habit but markedly impaired maze performance.