The genetic photosensitive epilepsy of the Fayoumi chicken was transferred to normal chickens by in situ grafts at 2 days of incubation, of both the prosencephalic and mesencephalic brain vesicles taken from epileptic embryos. However, mesencephalic graft is sufficient to allow convulsions under sound stimulation. Typical EEG patterns are recorded in chimeras having the prosencephalon plus or not the mesencephalon. We conclude that, in this mutant, the whole neural tissue is affected, but the seizure generator is localized inside the mesencephalon, and specific sensory pathways are necessary for seizures to occur.

Acoustic Stimulation↗

PubMedDate not supplied

Topographic organization of the interpositorubral connections in the rat. A WGA-HRP study.

The projections from the anterior (NIA) and posterior (NIP) interposed nuclei to the magnocellular red nucleus (RNm) have been investigated in the rat, using the retrograde transport of horseradish peroxidase-wheatgerm agglutinin conjugate. Projections from the NIA extend throughout the RNm, whereas those from the NIP only reach its medial aspect. In addition, a topographical organization of the NIA-RNm pathway was found, such that the medial NIA projects ventrally, the lateral NIA projects dorsally.

Animals↗

PubMedDate not supplied

The red nucleus activity in rats deprived of the inferior olivary complex.

The long-term effects of the inferior olive destruction on the red nucleus activity, were studied in the rat following injection of 3-acetylpyridine. As soon as the olivary activity was suppressed, the discharge of the rubral units drastically decreased. Then, they progressively recovered the control frequency during the first month, although a normal rubral activity was not restored up to 8 months. The hypothesis is advanced that the olivocerebellar system is essential to shape the activity of the rubrospinal pathway.

Animals↗

PubMedDate not supplied

Cerebellar Purkinje cells: membrane property changes on partial deafferentation.

The responses of the cerebellar Purkinje cell to removal of its climbing fiber input has been studied electrophysiologically in slices of rat cerebella. Using single electrode current clamp methods, membrane potentials were recorded in various conditions from normal and 3-AP deafferented Purkinje cells (PC). The membrane of the deafferented PC showed a rectification for hyperpolarizing currents which varied in degree with length of time after removal of the climbing fiber input. While this rectification was the most pronounced change in membrane properties provoked by the deafferentation, other more subtle effects were observed in experiments with changes in extracellular ionic compositions. Since the rectification began at membrane potentials near -60 mV, it could prevent membrane hyperpolarization by inhibitory synaptic inputs and thus produce an apparent hypersensitivity to excitatory inputs.

Animals↗

PubMedDate not supplied

[Study of pathways and function of the proprioceptive system in the extrinsic muscles of the eye].

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Animals↗