Activity of Purkinje cells, parallel fibers, and climbing fibers in the developing rabbit cerebellum

Abstract A study has been made of the activity of Purkinje cells, parallel fibers, and climbing fibers in 120 rabbits aged from a few hours to 20 days. Spontaneous simple spike activity due to activation by the mossy fiber‐granular cell‐Purkinje cell system has been found, and also a complex spike related to direct activation by the climbing fibers from the first few hours of life. Statistical analysis of unit discharges shows that there is a general linear increase in their frequency with age. The presence of a propagated spike in the parallel fibers and of complex discharges in the Purkinje cells in response to stimulation of afferent climbing fibers confirms that a large part of the cerebellar synaptic system is operative from the time of birth.