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Intracellular recording from spinal neurons during stimulation of paleo- and neo-cerebellum of cat
692
JOURNALOF
E V O L U T I O N A R Y B I O C H E M I S T R Y AND P H Y S I O L O G Y
Development of inhibition in spinal cord of kittens: By G. A. VARTANYAN and N. M. YAKOVLEV: Institute of Experimental Medicine of the Academy of Medical Sciences of the U S S R , Leningrad, pp. 353-358. As INDICATEDby the experiments with paired stimuli, "long-lasting" spinal inhibition in decapitated newborn kittens is of a presynaptic nature. Presynaptic inhibition in kittens differs from that in adult animals by its higher intensity and longer duration. Postsynaptic inhibition, which can be first demonstrated on the tenth to twelfth day of postnatal life, continues its development in further ontogenesis.
IntraceUular recording from spinal neurons during stimulation of paleo- and neo-cerebellnm of cat: By R. A. GmCORIAN: Institute of Evolutionary Physiology and Biochemistry of the Academy of Sciences of the U S S R , Leningrad, pp. 359-368. TI-m EFFECTof stimulation of phylogenetically different cortical areas of cerebellum on the activity of motoneurons and interneurons of the spinal cord have been studied intracellularly under slight nembuthal narcosis on cats rendered motionless by phlaxedile. Rhythmic stimulation of paleo-cerebellum (Culmen, HIV-HV) was accompanied by either a slight decrease in frequency or temporal complete arrest of the spontaneous discharges of motoneurons. During inhibition in most of the cells an increase in membrane potential and prolongation of after-discharge hyperpolarization have been observed. Stimulation of the vermal part of paleo-cerebellum facilitated rhythmic discharge in most of the motoneurons while neo-cerebellar stimulation (Crus, I, II; L paramedianus, HVIIA, HVIIB) of the same intensity was less effective and the discharge inhibition was never complete. The interneurons were more sensitive to rhythmic stimulation of cerebellum than motoneurons, and their long-lasting component (from the two hundredth to the five hundredth msec) of synaptically evoked discharge was inhibited completely though its primary component (up to 100msec) remained unaltered. Under the same conditions, neocerebellar stimulation did not prevent the development of both components of a discharge though slightly modified its interimpulse intervals. The descending inhibitory influences from cerebellum on spinal motoneurons is rendered not directly, but firstly by decreasing the background impulsation of interneurons which in its turn decreases the excitability of motoneurons.
Descending pathways from phylogenetically different parts of cerebellum to spinal cord in cat: By A. A. KOSAREVA:Institute of Evolutionary Physiology and Biochemistry of the Academy of Sciences of the U S S R , Leningrad, pp. 369377. SECTIONS of the upper cervical part of the spinal cord of the cat have been studied after decerebellation or stereotaxic lesions of the nuclei of paleo- and neo-cerebellum. Slices were impregnated using the Nauta and the Albrecht-Fernstrom techniques. It was found that paleo-cerebellum has direct descending projections to the spinal cord. Direct projections from neo-cerebellum to the spinal cord were not demonstrated.
JOURNALOF
E V O L U T I O N A R Y B I O C H E M I S T R Y AND P H Y S I O L O G Y
Development of inhibition in spinal cord of kittens: By G. A. VARTANYAN and N. M. YAKOVLEV: Institute of Experimental Medicine of the Academy of Medical Sciences of the U S S R , Leningrad, pp. 353-358. As INDICATEDby the experiments with paired stimuli, "long-lasting" spinal inhibition in decapitated newborn kittens is of a presynaptic nature. Presynaptic inhibition in kittens differs from that in adult animals by its higher intensity and longer duration. Postsynaptic inhibition, which can be first demonstrated on the tenth to twelfth day of postnatal life, continues its development in further ontogenesis.
IntraceUular recording from spinal neurons during stimulation of paleo- and neo-cerebellnm of cat: By R. A. GmCORIAN: Institute of Evolutionary Physiology and Biochemistry of the Academy of Sciences of the U S S R , Leningrad, pp. 359-368. TI-m EFFECTof stimulation of phylogenetically different cortical areas of cerebellum on the activity of motoneurons and interneurons of the spinal cord have been studied intracellularly under slight nembuthal narcosis on cats rendered motionless by phlaxedile. Rhythmic stimulation of paleo-cerebellum (Culmen, HIV-HV) was accompanied by either a slight decrease in frequency or temporal complete arrest of the spontaneous discharges of motoneurons. During inhibition in most of the cells an increase in membrane potential and prolongation of after-discharge hyperpolarization have been observed. Stimulation of the vermal part of paleo-cerebellum facilitated rhythmic discharge in most of the motoneurons while neo-cerebellar stimulation (Crus, I, II; L paramedianus, HVIIA, HVIIB) of the same intensity was less effective and the discharge inhibition was never complete. The interneurons were more sensitive to rhythmic stimulation of cerebellum than motoneurons, and their long-lasting component (from the two hundredth to the five hundredth msec) of synaptically evoked discharge was inhibited completely though its primary component (up to 100msec) remained unaltered. Under the same conditions, neocerebellar stimulation did not prevent the development of both components of a discharge though slightly modified its interimpulse intervals. The descending inhibitory influences from cerebellum on spinal motoneurons is rendered not directly, but firstly by decreasing the background impulsation of interneurons which in its turn decreases the excitability of motoneurons.
Descending pathways from phylogenetically different parts of cerebellum to spinal cord in cat: By A. A. KOSAREVA:Institute of Evolutionary Physiology and Biochemistry of the Academy of Sciences of the U S S R , Leningrad, pp. 369377. SECTIONS of the upper cervical part of the spinal cord of the cat have been studied after decerebellation or stereotaxic lesions of the nuclei of paleo- and neo-cerebellum. Slices were impregnated using the Nauta and the Albrecht-Fernstrom techniques. It was found that paleo-cerebellum has direct descending projections to the spinal cord. Direct projections from neo-cerebellum to the spinal cord were not demonstrated.