Multiunit activity of the cerebellar cortex during a learned motor task (author's transl)

Multiunit activity from the anterior lobe of the cerebellar cortex (pars intermedia) was recorded in chronic cats during a learned motor task. The animals were trained to perform a succession of rapid flexion-extension arm movements alternating with two maintained postures. No significant differences were observed in the corticocerebellar activity (ECeG) during maintained postures. However an increase of activity occurred before the beginning of the flexion detected on the biceps EMG recordings. The first ECeG modifications occurred in synchrony with postural reorganization preceding the flexion. This latter involved primarily the triceps. The increase of activity took place during the execution of movement and ended with the reaching of the target. The results are discussed in relation to the latest hypotheses on cerebellar involvement in motor regulation.     

Corticocerebellar unit activity and ocular movements: saccadic-related changes during sleep and waking (author's transl)

Single unit activity of vermian oculomotor cortex (Lobules V, VI, VII) and conjugated horizontal rapid eye movements were recorded in the cat, during wakefulness (W) and paradoxical sleep (PS). Correlation between cerebellar and oculomotor events showed the following findings. During PS the units — mostly Purkinje (P) cells — all increased their rate of discharge (mossy fiber activation for P cells) in coincidence with saccadic movements. Two kinds of movement related cells were observed: (i) Most of the units showed an increase of their discharge rate together with occasional bursts. These events were related to magnitude and rate of the saccades without accurate synchronization. (ii) Some cells showed a burst type activation strictly synchronized with the rapid eye movements of sleep. During W, two thirds of the units changed their pattern of discharge (mossy fiber activation for P cells) with waking ocular activity. Modifications of discharge patterns were very different from cells to cells (activation or suppression, increase or decrease in the rate of discharge). Many cells had an accurately synchronized response with the saccades. Some units had a directional reactivity, others gave a similar response for opposite eye movements. P cells showed an increase of their climbing fiber driven activity during PS with eye movements compared with PS without saccades. During PS and W, complex spikes discharges of P cells evidently showed no accurate relation to saccadic eye movements. Functional significations of the above described events are also discussed.     

Topographic analysis of areas of negative and positive reinforcement in the central grey matter of the rat (author's transl)

Utilization of a movable electrode has permitted an analysis of areas of negative reinforcement (switch-off response) and areas of positive reinforcement (self-stimulation responses), as well as the behavioral effects of a simultaneous activation of systems of negative and positive reinforcement at the ambivalent sites of a junction-area. Within the areas of reinforcement, gradients were uncovered in the rates of both switch-off and self-stimulation responses.     

Effects of cycloheximide on acquisition and retention of an avoidance learning in the rat: recovery of memory (author's transl)

Thirty minutes before an avoidance learning session in a Y maze, rats were given a subcutaneous injection of either cycloheximide (2,5 mg/kg) or saline. The animals were trained to a criterion of 4 or 8 consecutive avoidance responses. Retention tests were given 2 hr, 24 hr or 6 days after initial learning. The results show: (1) acquisition is not affected by the severe protein synthesis inhibition; (2) impairment of memory is found only in the low criterion experimental group 2 hr after learning and (3) in both experimental groups 24 hr after learning; (4) a recovery of memory is observed in both groups 6 days later. A control experiment indicates that the deficits found cannot be regarded as retrieval deficits. Transient amnesia is interpreted in terms of slowing down in long-term memory establishment process and this is thought to be due to a decrease in the rate of neurotransmitter synthesis.