[Electrophysiological study of the corticonuclear projection in the lobule VII of cat cerebellum].

Antidromic field potentials and antidromic unit responses of Purkinje cells (PCs) to the stimulation of fastigial nucleus (FN), interposed nucleus (IN) and dentate nucleus (DN) were respectively recorded from the lobule VII of posterior cortex of decerebrated cats, to identify the corticonuclear projection in the lobule VII. After antidromically identified, simple and complex spike responses of PCs to natural peripheral forepaw extension-flexion stimuli were observed. All data were analysed by a computer, and average field potentials and poststimulus time histograms (PSTHs) were constructed. The results show that the corticonuclear zones are sharply demarcated on the lobule VII of posterior cortex. The boundary between the fastigial zone (FZ) and the interposed zone (IZ) on the lobule VII is not straight, but bends. Among sublobule VII Aa-VII Ad the FZ-IZ boundary bends from 2.8 mm to 1.5 mm laterally to the midline. The boundary between IZ and dentata zone (DZ) was about 5.0 mm away from the midline. The PSTHs of the simple and complex spike activities showed that part of PCs in all three different corticonuclear zones responded to the forepaw flexion-extension stimulation, but proportion of the cells affected was quite different among the three zones. In the IZ 84% PCs were modulated by the forepaw stimulation, while in the FZ and DZ it was 59% and 20% respectively. These results support previous finding that information processing involved in the modulation of Purkinje cell activity in response to the forepaw stimulation occurs in all 3 zones examined.