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Biomedical subjects

C Batini

Publications and source records attributed to C Batini.

At least 55 records · Page 3Linked to original sources
PubMed1984

Metabolic activity of intracerebellar nuclei in the rat: effects of inferior olive inactivation.

Metabolic activity of the intracerebellar nuclei during cryoinactivation of the inferior olive was studied in the anaesthetized rat by using the 14C-2-deoxyglucose method. Single unit recording of Purkinje cells was simultaneously monitored in the cerebellar cortex. Local inactivation in the inferior olive resulted in regional suppression of complex spike discharges in the cerebellar cortex. An increased metabolic activity was observed in the cerebellar nuclei contralateral to the cryoinactivation site correlating the somatotopically arranged olivo-cerebello-nuclear circuit. This increase was shown to be due specifically to inactivation of the inferior olive, since it was not obtained in a rat in which the inferior olive was previously destroyed by neurotoxic doses of 3-acetylpyridine. The results are interpreted as being due to an increased presynaptic activity of the terminals of the Purkinje cells which fire simple spikes at high rates after climbing fibre deafferentation.

Animals↗
PubMed1984

[Depression of the efferent activity of the cerebellar nuclei following destruction of the inferior olive].

The spontaneous discharge frequency of the fastigial and interpositus nuclei was evaluated in three experimental conditions in Rat: (a) in the "intact" animal; (b) in animals with total and selective destruction of the inferior olive, depriving the Purkinje cells of their afferent climbing fiber; (c) in animals having inferior olive destruction and cryocoagulation of the cerebellar cortex, destroying Purkinje cells innervating the neurones of the fastigial and interpositus nuclei. Unit activity was high in group (a) (32.9 +/- 22.9/s); it was markedly reduced in group (b) (1.1 +/- 1.3/s); it was higher in group (c) than in group (a) (43.7 +/- 25.5/s). Suppression of the inferior olive thus increases the Purkinje cell inhibitory action upon neurones of the cerebellar nuclei.

Animals↗
PubMed1984

[Long-term changes in the activity of Purkinje cells and efferent cerebellar neurons following bilateral destruction of the inferior olive].

The spontaneous discharge frequency of Purkinje cells and neurones of the cerebellar nuclei was evaluated in rats after complete bilateral destruction of their inferior olive with 3-acetylpyridine, performed one day to six months before. The deafferentation from the climbing fibers produced an increased inhibitory action of the Purkinje cells on their target neurones, lasting at least for one week. A relative compensation took place progressively during the first month, but the normal activity of the circuit did not recover even after six months.

Animals↗
PubMed1983

Decrease of [14C]2-deoxyglucose uptake at the intracerebellar nuclei during cerebellar cortex stimulation.

The effect of electrical stimulation of the cerebellar cortex at 10-30 c/s on metabolism in the intracerebellar nuclei has been studied using the [14C]2-deoxyglucose method. The experiments, performed on anesthetized or immobilized animals did not produce any detectable changes in the radioautographic labeling of the intracerebellar nuclei compared with controls. Experiments were also performed in animals pretreated with 3-acetylpyridine neurotoxin which selectively destroys the inferior olive and produces an intense labeling of the intracerebellar nuclei. Less marking was observed in restricted regions of the intracerebellar nuclei receiving the axon terminals of the stimulated Purkinje cells if the experiments were done within the first few hours. Following 3-acetylpyridine intoxication, in this early phase, destruction of the inferior olivary cell bodies occurs, but the climbing fibers remain intact. At 2 days or more following 3-acetylpyridine, changes in marking with stimulation could no longer be obtained. The finding is interpreted as being due to an actual reduction of the Purkinje cell activity upon stimulation of the cerebellar cortex, leading to a reduction of the metabolic activity at their presynaptic terminals.

Animals↗
PubMed1983

Cerebellar output regulation by the climbing and mossy fibers with and without the inferior olive.

The activity of the olivocerebellar complex and the structures related in series with it have been studied using the complementary action of harmaline and 3-acetylpyridine to isolate the two principal inputs to the cerebellar Purkinje cells. The activities of the various nuclei as well as the entire brain have been simultaneously monitored using the [14C]2-deoxy-glucose method under the various combined effects of the pharmacological agents. (1) Tremogenic doses of harmaline increased the frequency of discharge in selected parts of the olivocerebellar system, increasing climbing fiber input and reducing Purkinje cell simple spike discharges in corresponding parts of the cerebellar cortex. The metabolic activity increased in the inferior olive and in the red nucleus. The results are interpreted as a net reduction of Purkinje cell inhibition on their target neurons, leading to a facilitatory cerebellar output. (2) Systemic injection of neurotoxic doses of 3-acetylpyridine selectively produced total degeneration of the neurons in the inferior olive, resulting in the suppression of complex spikes and a net increase in simple spike output from the Purkinje cells. The metabolic consequences were a reduction or absence in the inferior olive, decrease in the red nucleus, and increases in the Purkinje cell target neuron regions, including the intracerebellar and vestibular nuclei. The study of long survival times following the neurotoxic treatment revealed a transient metabolic marking of the inferior olive during the active glial processes accompanying the degeneration. In other parts the radioautographic changes caused by the destruction of the inferior olive persisted for about 1 month after the administration of the drug. (3) Tremogenic doses of harmaline were given to rats at different times following treatment with 3-acetylpyridine. It was demonstrated that: (a) intoxication of the inferior olive started within the second hour after 3-acetylpyridine administration, corresponding to the time at which the metabolic response to harmaline was also abolished; and (b) the increased metabolic activity produced by harmaline in the olivocerebellar complex was a consequence of an increased activity of the neurons of the inferior olive rather than a direct pharmacological effect of the drug. (4) Partial lesions of the inferior olive led to increased metabolic activity of those parts of the intracerebellar nuclei topographically related to the destroyed parts of the inferior olive. (5) In 3-acetylpyridine-treated animals, local ablation as well as local inactivation of the cerebellar cortex produced localized suppression of the intense labeling in the intracerebellar nuclei obtained in these animals. Since these regions receive synapses which are normally inhibitory, suppression of labeling clearly supports the hypothesis that regional marking may very well be produced by the activity of the presynaptic terminals themselves...

Animals↗
PubMed1983

Cerebellar output response to afferent stimulation: energy consumption and unit activity in the cat fastigial nucleus.

The cerebellar output function was studied using cerebellopetal proprioceptive stimulation which produces simple and complex excitatory discharges as well as inhibitory activity in the Purkinje cells. The activity of the intracerebellar nuclei (and of the entire brain stem) was measured by the energy consumption as revealed with the [14C )-2-deoxyglucose method. The stimulations consisted of repetitive (1-20 c/s) electrical excitation of the nerve leading to the inferior oblique, to the masseteric and to the gastrocnemius soleus muscle. Compared to a group of non-stimulated controls, heavy bilateral labeling was obtained in the posterior pole of the fastigial nucleus. This was not observed with stimulation of the vibrissal pad which, however, produced a clear increase of [14C]-2-deoxyglucose uptake in the secondary trigeminal complex. Labeling of the posterior part of the fastigial nuclei was suppressed by ablation or pharmacologic inactivation of the overlying cerebellar cortex which suppresses the inhibitory activity of the Purkinje cells into the nuclear cells. Labeling of the posterior fastigial nuclei was also decreased in animals not stimulated but with ablation or pharmacologic inactivation of the overlying cerebellar cortex. The hypothesis proposed is that the marking results are the consequence of an increased activity in the Purkinje cell terminals. The activity of the Purkinje cells was also recorded extracellulary both before and during repetitive stimulation of a muscle nerve. The discharge activity of those in the cerebellar vermis and giving axons to the posterior fastigial nucleus was increased by the stimulation, whereas the activity of those of the hemispheral parts remained unchanged. Units in the fastigial nucleus were also recorded. Their activity was found to be deeply depressed so that only a few units were encountered and no further decrease of their discharge could be detected with the stimulation of a muscle nerve. Nevertheless, using the present data and those previously obtained, the conclusion is advanced that the cerebellar output function is actually decreased during afferent cerebellar stimulation.

Afferent Pathways↗
PubMed1982

[Cerebellar disfacilitation after pharmacological destruction of the inferior olive].

The total selective destruction of the inferior olive by 3-acetylpyridine produces a marked increase in the metabolic activity at the intracerebellar nuclei. This increase is locally suppressed by partial ablation or local inactivation of the corresponding regions in the cerebellar cortex, suggesting its localization in the intranuclear presynaptic terminals of the Purkinje cells. In a second series of experiments, it is demonstrated that Purkinje cells of the cerebellar cortex deprived of their climbing fibers and therefore of their complex spikes by destruction of the inferior olive, increase their firing frequency of simple spikes. As a consequence, there is a decreased frequency of discharge of their target neurones in the intracerebellar nuclei; the net result of suppression of the inferior olive is thus an increased cortico-nuclear inhibitory effect.

Animals↗
PubMed1981

[Regulation of metabolic activity of intracerebellar nuclei].

The metabolic activity of the intracerebellar nuclei was studied in the cat, using the radioautographic method of marking active brain structures with 14C-2-deoxyglucose. Electrical stimulation of afferent fibers in the muscle nerve of an extrinsic eye muscle was used to activate mossy and climbing cerebellar afferents. A heavy bilateral labelling of the posterior parts of the fastigial nuclei was consistently obtained compared to controls. This result could no longer be obtained after ablation or inactivation of the cerebellar cortex overlying this part of the fastigial nuclei.

Afferent Pathways↗
PubMed1981

Harmaline-induced tremor. I. Regional metabolic activity as revealed by [14C]2-deoxyglucose in cat.

Changes of local cerebral glucose consumption under the effect of tremogenic doses of harmaline were studied. To find the brain structures activated by the drug, the autoradiographic method using [14C]2-deoxyglucose was applied to young cats. After administration of harmaline, the animals were paralized with flaxedil. Results were compared to a group of control animals not injected with the drug, but submitted to the same experimental protocol. Increases of neuronal activity were observed in several structures. A) Among the relays of the olivo-cerebello-fastigio (and vestibulo)-reticulo-spinal circuit that had been claimed to fire at the frequency of the tremor, labeling was found in: 1. selected portions of the inferior olive including the medial accessory olive and the caudolateral part of the dorsal accessory olive; 2. the molecular layers of the cerebellar cortex including vermian and paravermian zones. Labeling of the olivo-cerbellar system was therefore larger than the compartment controlling the fastigial nucleus and extended to that controlling the interpositus nucleus. B) Other structures not under the direct control of the olivo-cerebellar system displayed increased radioactivity under harmaline: lateral reticular nucleus, nucleus reticularis tegmenti pontis, red nucleus and basal ganglia. Part of the nucleus ambiguus, intensely labeled in the control animals, showed decreased radioactivity under harmaline. The experiments were repeated with the same protocol in another group of animals with unilateral sections of the inferior cerebellar peduncle in order to distinguish between a direct pharmacological influence and a nervous one. Marking of the basal ganglia was not affected by pedunculotomy, suggesting a direct "pharmacological" action of the drug in this cases. On the other hand, marking of the other labeled structures was asymmetric or suppressed by pedunculotomy, and therefore could result from a "nervous" effect secondary to activation of the inferior olive.

Alkaloids↗
PubMed1981

Harmaline-induced tremor. II. Unit activity correlation in the interposito-rubral and oculomotor systems of cat.

Units were recorded extracellularly in the cat brainstem under the effect of tremogenic doses of harmaline. They were localized post mortem and the units discharging at the harmaline tremor frequency were mapped. Harmaline-sensitive neurons were found in the bulbo-pontine reticular formation, in particular, in the lateral reticular nucleus and the nucleus reticularis tegmenti pontis. The nucleus interpositus as well as the red nucleus also displayed numerous units discharging at the tremor frequency, indicating that the cerebello-interposito-rubro-spinal system controlling the flexor muscles participate in harmaline tremor. Participation of the oculomotor system in the harmaline-induced tremor was tested at the level of the vestibular neurons relaying the vestibulo-ocular reflex, the motoneurons, the eye muscles and the eye movements. No rhythmic discharge at the tremor frequency nor eye movements could be detected, indicating that harmalie tremor does not affect the oculomotor system.

Alkaloids↗
PubMed1980

[Harmaline tremor: activity of the interposito-rubral system and of the bulbo-ponto-reticular formation].

The effects of tremogenic doses of harmaline have been studied by extracellular unit recordings and 14C 2-deoxyglucose marking in two groups of cats. Harmaline sensitive neurons were found in the lateral reticular nucleus and the nucleus reticularis tegmenti pontis. The nucleus interpositus as well as the red nucleus were also found to be discharging at the tremor frequency, indicating that the cerebello-interposito-rubral system participates in harmaline tremor. In cats with unilateral sections of the inferior cerebellar peduncle, 14C 2-deoxyglucose marking demonstrated that the increased activity previously observed in those structures was a consequence of harmaline acting on the inferior olive.

Alkaloids↗
PubMed1979

[Interaction between the vestibulo-ocular and the oculomotor systems].

Optomotor nystagmic activity has been elicited in the "encéphale isolé" cat during repetitive electric stimulation of selective oculomotor regions of the frontal cortex and superior colliculus. These regions were nystagmogenic only when facilitated by a cortical arousal or a vestibular activation.

Animals↗
PubMed1979

Interaction between the horizontal vestibulo-ocular reflex and optokinetic response in rabbits.

Dynamic characteristics of the horizontal vestibulo-ocular reflex (HVOR), the optokinetic response (OKR), and their interactions were investigated in alert albino rabbits. For stimulation of the horizontal semicircular canals, the whole rabbit was rotated sinusoidally on a motor-driven turntable at peak-to-peak amplitudes of 5 degrees to 30 degrees over a frequency range of 1/30 to 1/2 Hz. Optokinetic stimulation was provided by a narrow vertical slit light source presented in front of the eye to be tested. The evoked horizontal eye movements were observed and measured by means of a closed circuit television system adapted to provide an analog signal proportional to the eye movement. The net HVOR was obtained by rotation of the turntable in darkness and the net OKR by rotation of the light source. Combining rotation of the turntable with a stationary light source immediately increased the gain and reduced the phase shift of the HVOR. The light source moving in phase with the turntable, but at twice the angular amplitude, reduced the gain and advanced the phase of the HVOR. Eye movement curves of the HVOR modified by a fixed or moving slit light could be reconstructed approximately by a linear combination of the net HVOR and OKR.

Animals↗
PubMed1979

Olivo-cerebellar activity during harmaline-induced tremor.A 2-[14C]deoxyglucose study.

The specific neuronal activity of the olivo-cerebellar system of the cat under the effect of harmaline has been studied using the 2-[14C]deoxyglucose method. The results obtained in animals treated with tremogenic doses of harmaline, but immobilized with flaxedil, have been compared with those of non-treated controls. An increased radioactivity in specific regions of the olivo-cerebellar system including parts of the medial and dorsal accessory olive and the corresponding receiving molecular layer have been found. No involvement of the granule cell layer nor of the nuclear cells has been observed. It is therefore suggested that the tremogenic rhythmicity of the cerebellar output is organized uniquely by an increased climbing fiber input.

Alkaloids↗