Abstract
The effects of drugs on the potentials evoked by electrical stimulation on the sensorirnotor area (SMA), nucleus reticularis tegmenti pontis (PTRN), nucleus reticularis lateralis (LRN), nucleus olivaris inferior (ION), or superficial radial nerve (SR) were investigated in cat cerebellar cortices. Pentobarbital-Na decreased the amplitude of the potentials evoked by all stimulations at every recording site. Pentobarbital-Na remarkably decreased the SMA or PTRN-stimulation induced evoked potentials in the anterior lobe. Chlorpromazine decreased the amplitude of the potentials evoked by SMA stimulation on the anterior lobe and ipsilateral crus I, and the drug increased it on the posterior lobe and contralateral crus I. With precerebellar nuclei stimulations, chlorpromazine decreased the amplitude of the evoked potentials in cerebellar cortices, whereas SR stimulation-evoked potentials were remarkably increased in amplitude. Meprobamate increased the amplitude of the potentials evoked by precerebellar nuclei or SR stimulation at an early stage and then decreased it. Caffeine, picrotoxin, and strychnine remarkably increased the amplitude of the potentials in cerebellar cortices evoked by all stimulations. Strychnine in particular significantly increased the amplitude of the potentials evoked by SR stimulation. These results strongly indicate that CNS depressants and stimulants affect the cerebellar afferent pathways, probably in an indirect manner.
