The results collected by electrical microstimulation of the nucleus lateralis of the cerebellum in anaesthetized rats may be summarized as follows. The stimulations evoked motor effects in head and forelimb principally whereas hindlimb was only occasionally involved. The movements were prevalently segregated to only one joint (simple movements), in a lesser degree they involved two or three segments (complex movements). Simple and complex movements were apparently distributed in the nuclear mass without topographical segregation or preferentiality. The electromyographic records suggest that the neocerebellar movements are of synergistic nature. A somatotopical organization was evidenced within the nucleus lateralis: 3 specific functional regions were identified in the caudorostral nuclear extension. They concern the forelimb (caudally), head (centrally) and hindlimb (rostrally). This somatotopical organization persisted unmodified following elimination of either the cerebral motor cortex alone or in addition to that of the red nucleus. The nuclear subdivisions of the cerebellar nucleus lateralis showed functional differences: (1) the dorsolateral hump of Goodman et al. was principally involved in lip movements; (2) the subnucleus lateralis parvocellularis elicited movements of single vibrissae, neck and medio-distal segments of the forelimb, prevalently; (3) the magnocellular subdivision essentially controlled both limbs with large prevalence for their medio-proximal segments. To identify the functional role of the different descending pathways which relay the neocerebellum to the cord, the motor effects evoked in intact rats were compared with those elicited in rats submitted to cortical ablation and/or to lesion of the red nucleus region. The integrity of the cerebral cortex was essential only for distalmost forelimb motor activities. After lesion of the rubral region (which concomitantly eliminates corticospinal output), the stimulation of the nucleus lateralis evoked motor effects of the proximo-axial segments prevalently with intensity thresholds increased above two-fold those obtained in intact/decorticated rats. The movements elicited in rats with injury of the red nucleus region, including the ascending fibers of the brachium conjunctivum, are presumably mediated to the spinal cord through the reticulospinal pathway. The proportion of simple and complex movements decreased and increased respectively after cortical ablation and further on after injury of the red nucleus region. The discussion on the motor effects elicited in rats by the neocerebellum focussed on the possible role of 3 descending pathways.(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia↗

PubMedDate not supplied

The dentatorubral projection in the rat: an autoradiographic study.

The dentatorubral projection has been mapped in rats using autoradiography. Any part of lateral cerebellar nucleus (NL) projects throughout the contralateral parvocellular red nucleus (NRp) rostrocaudally; the projection is topographically organized: (1) a caudorostral shift in the NL corresponds to a dorsoventral displacement through the NRp; matching of this arrangement with the origin of rubrospinal projections is discussed; (2) only ventral parts of the NL, including the parvocellar subnucleus, project to the lateral edge of the NRp.

Animals↗

PubMedDate not supplied

[Excessive 7-14-sec positive spikes during REM sleep in monozygotic non-epileptic twins with speech retardation (author's transl)].

6-14/sec positive spikes (PS) (in our cases 7-14) were observed during 6 all-night sleep, recordings in one pair of monozygotic twins (aged 7 years), who had severe speech retardation, no epilepsy and were otherwise normal (CAT were normal). The EEG during wakefulness and sleep showed multifocal independent spikes over the left mid-temporal and right parieto-occipital area. The 7-14 PS, which were similar in both twins, occurred slightly during light sleep, were absent during slow sleep and were most prominent during REM sleep (mean=6.3 sec of PS bursts/min of REM). During REM sleep, the 7-14 PS bursts were negatively related to bursts of eye movements; PS were 7 times more frequent in the intervals between than during bursts of eye movements. In addition, long bursts of PS (up to 6 sec) might interupt the bursts of eye movements suggesting a functional antagonism between mechanisms (still unclear) responsible for PS and for REM. The predominance of PS during REM sleep and the inverse relationship with eye movements are not peculiar to our case, since similar findings have been reported in other cases (TSUZUKI 1967; OKUMA et al. 1968). During the sleep stages when Ps occurred spontaneously, PS could also be evoked by a click or a tone, with a latency of 1, 5-2 sec.

Auditory Perception↗