Page 10 - UNIT 3
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2.1. Neuronal circuit of the functional unit.
The neuronal circuit of the functional unit is
repeated with little variation 30 million times in the
cerebellum.
The output from the functional unit is from a deep
nuclear cell that continually receives excitatory and
inhibitory influences.
The excitatory influences arise from
afferent fibers that enter the cerebellum
from the brain or the periphery.
The inhibitory influence comes only from
the Purkinje cell (in the cortex of the
cerebellum).
The climbing cells and the parallel fibers activate
the Purkinje cells: the Mossy fibers make synapses
with the granule cells, which activate the parallel
fibers that will activate the Purkinje cells.
The afferent inputs to the cerebellum are mainly two: (1) the climbing fiber type and (2) the mossy
fiber type.
(1) Climbing fibers: they originate from the inferior olives of the medulla.
These climb through the dendrites of the Purkinje cells and there’s one climbing fiber
for each 5 to 10 Purkinje cells.
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