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V Perciavalle

Publications and source records attributed to V Perciavalle.

66 records · Page 4Linked to original sources
PubMed1980

Single muscle organization of interposito-rubral projections.

In unanesthetized neuraxis intact cats microstimulation of the interpositus nucleus (IN) which activated a single flexor or extensor muscle in limbs, was used to investigate changes of unitary discharged of rubrospinal (RST) cells. Recordings were made from sites the stimulation of which excited the same muscle activated by the IN (agonist cells), its antagonist (antagonist cells) or heteronymous muscles (heteronymous cells). Cats submitted to chronic cerebellar decortication, acute brachium conjunctivum (BC) section, acute prerubral hemidecerebration or chronic prerubral hemidecerebration and contralateral BC section, were used as controls. It was shown that agonist RST cells were monosynaptically fired from IN, while antagonist cells were inhibited and the heteronymous ones were not influenced. Cerebellar efferents within the BC mediate both excitatory and inhibitory effects, but cerebellar cortex and prerubral structures were not involved in their production.

Animals↗
PubMed1979

A computer model of intermediate cerebellum dynamic operations in motor control.

An intermediate cerebellum theoretical model for processing central programming discharges and muscle force signals is described which can perform a correct motor task under different peripheral perturbations (loads). An indispensable condition is that the simulated interpositus nucleus cells controlling a given effector (muscle) are inhibited by impulses coming from that effector (negative feedback from muscle force detectors). The hypothesis is proposed that the intermediate cerebellum can act via the rubrospinal tract as an interface between programming and executing motor structures.

Cerebellum↗
PubMed1978

Computer simulated discharges of thalamic ventrobasal neurones during sleep and wakefulness.

A theoretical model is described which in response to combinations of poissonian pulse trains with different mean frequencies on three independent incoming lines, generated output signals simulating spontaneous discharges of thalamic ventrobasal (VB) neurones during sleep and wakefulness. Some dynamic neuronal properties as refractoriness, facilitation, short term memory were simulated and characteristics of response to single pulses on different lines properly selected to reproduce those exhibited by VB neurones upon artificial stimulation of thalamic afferent systems. The data obtained from the model are briefly discussed in relation to possible contributions of specific and nonspecific afferent systems in producing spontaneous VB discharges characteristic of different levels of vigilance.

Action Potentials↗
PubMed1978

Motor responses evoked by microstimulation of restiform body in the cat.

Motor effects produced by microstimulation of restiform body (RB) were studied in acute unanesthetized cats, using tungsten electrodes for stimulating the peduncle and bipolar steel electrodes for recording muscular activity (EMG). The main results were the following. 1. Threshold microstimulation (18.24 microA +/- 8.77 S.D.) of effective foci within RB elicited single muscle contractions of ipsilateral limbs, primarily of forelimb; overthreshold activation (32.83 microA +/- 9.25S.D.) of the same points produced complex movements in 61.54% of cases that involved muscles of shoulder, neck, and trunk. 2. Single muscle contractions exhibited a mean latency (20.09 msec +/- 2.04 S.D.) which was significantly longer than that shown by complex movements (10.00 msec +/- 3.10 S.D.). Furthermore, a decrease in frequency of stimulating train below 300 Hz and a reduction in duration below 30 msec caused a steep rise of threshold for single muscle responses that was not observed when studying complex movements. 3. Acute RB interruption between stimulating electrode and cerebellum abolished single muscle contractions; conversely, complex movements remained unmodified even when the RB was lesioned in cats chronically submitted to interruption of brachium conjunctivum (BC). 4. The pathway involved in promoting RB induced single muscle activation includes interpositus nucleus, BC and rubrospinal tract. Possible modalities of RB afferent participation to the motor control are briefly discussed.

Animals↗
PubMedDate not supplied

Influences of cerebral cortex and cerebellum on the red nucleus of the rat.

The aim of the present work was to investigate the unitary responses of neurons belonging to the magnocellular and parvocellular division of the red nucleus (RN) to stimulation of efferents from motor cortex and cerebellum. In anesthetized rats spontaneous discharges of rubro-olivary (RO) and rubrospinal (RS) neurons were tested for stimulation of motor cortex (CX), pyramidal tract (PT), interpositus (IN) and dentate (DN) cerebellar nuclei. It has been observed that the majority of RO and RS neurons were influenced by stimulation of both IN and DN as well as by activation of CX and PT. These results indicate that (1) a segregation of cerebral and cerebellar afferents to RN of rat does not exist and (2) convergent responses from the same cerebral and cerebellar structures have been observed in a high number of both RS and RO neurons.

Animals↗