Synaptic currents in cerebellar Purkinje cells

Arthur Konnerth, Isabel Llano, Clay M. Armstrong

Research output: Contribution to journalArticlepeer-review

324 Scopus citations

Abstract

Cerebellar Purkinje cells are known to receive strong excitatory input from two major pathways origi-nating outside the cerebellum and inhibitory input from two types of neurons in the cerebellar cortex. The functions and synaptic strengths of these pathways are only partially known. We have used the patch-clamp technique applied to Purkinje cells in thin slices of rat cerebellum to measure directly the postsynaptic currents arising from the two major excitatory pathways and one of the inhibitory inputs. Inhibitory synaptic currents occur spontaneously with high frequency and are variable in amplitude, ranging, in our recording conditions with high internal Cl-, from less than 100 pA to more than 1 nA. These currents are blocked by the γ-aminobutyrate type A antagonist bicuculline. One of the excitatory inputs is all or none. For threshold stimulation, the synaptic current is either full amplitude, when the presynaptic fiber is successfully stimulated, or completely absent. This synaptic current is often larger than 1 nA and is virtually eliminated by 2 μM 6-cyano-7-nitroquinoxaline-2,3-dione, a blocking agent thought to be specific for glutamate receptors that are not of the N-methyl-D-aspartate type. Its all-or-none character identifies it as arising from a climbing-fiber synapse. The other excitatory input produces a synaptic current that is smoothly graded as a function of stimulus intensity. This response we believe arises from the stimulation of mossy fibers or granule cells. The synaptic current associated with this input is also largely eliminated by 2 μM 6-cyano-7-nitroquinoxaline-2,3-dione.

Original languageEnglish
Pages (from-to)2662-2665
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number7
DOIs
StatePublished - Apr 1990
Externally publishedYes

Keywords

  • Brain slices
  • Climbing fiber
  • Glutamate receptors
  • Parallel fiber
  • Patch clamp

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