Journal of Neuroscience, Vol 9, 2141-2150, Copyright © 1989 by Society for Neuroscience
Physiological and anatomical studies of the interactions between Purkinje cells and basket cells in the cat's cerebellar cortex: evidence for a unitary relationship
DL O'Donoghue, JS King and GA Bishop
Department of Anatomy, Ohio State University, Columbus 43210.
Intracellular recordings have been obtained from neurons in lobule V of the
cat's vermis, which were identified as basket cells following intracellular
injections of HRP. Stimulation of the inferior cerebellar peduncle or
peripheral nerves elicited an initial depolarizing and subsequent
hyperpolarizing response. Neither potential could be graded with changes in
stimulus intensity; both displayed all-or-none properties at threshold
levels of stimulation. The depolarization and hyperpolarization were
confirmed as an excitatory postsynaptic potential and an inhibitory
postsynaptic potential (IPSP), respectively, on the basis of their response
to intracellular injections of hyperpolarizing and depolarizing currents
into the cell body. A possible source of the unitary IPSP is the Purkinje
cell, via its recurrent axonal collaterals. To test this hypothesis, an
electron microscopic analysis was carried out to define the synaptic
relationships between the recurrent collaterals of an HRP-filled Purkinje
cell and 3 basket cells. Serial section analysis reveals that collaterals
from a single Purkinje cell contact several basket cells, but each basket
cell received somatic input from only one Purkinje cell. These data provide
an anatomical substrate for the unitary IPSP observed during intracellular
recording from basket cells. The unitary nature of the Purkinje cell-basket
cell interaction indicates that a very limited population of cortical
neurons may be involved in local circuits that integrate afferent
information in the cerebellar cortex.