Potentiation of mossy fiber EPSCs in the cerebellar nuclei by NMDA receptor activation followed by postinhibitory rebound current.
Behavioral and computational studies predict that synaptic plasticity of excitatory mossy fiber inputs to cerebellar nuclear neurons is required for associative learning, but standard tetanization protocols fail to potentiate nuclear cell EPSCs in mouse cerebellar slices. Nuclear neurons fire action potentials spontaneously unless strongly inhibited by Purkinje neurons, raising the possibility that plasticity-triggering signals in these cells differ from those at classical Hebbian synapses. Based on predictions of neuronal activity during delay eyelid conditioning, we developed quasi-physiological induction protocols consisting of high-frequency mossy fiber stimulation and postsynaptic hyperpolarization. Robust, NMDA receptor-dependent potentiation of nuclear cell EPSCs occurred with protocols including a 150-250 ms hyperpolarization in which mossy fiber stimulation preceded a postinhibitory rebound depolarization. Mossy fiber stimulation potentiated EPSCs even when postsynaptic spiking was prevented by voltage-clamp, as long as rebound current was evoked. These data suggest that Purkinje cell inhibition guides the strengthening of excitatory synapses in the cerebellar nuclei.
Pugh
Jason R
JR
Institute for Neuroscience, Northwestern University, Evanston, Illinois 60208, USA.
Raman
Indira M
IM
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001245:Association Learning / Q000502:physiology; D002529:Cerebellar Nuclei / Q000187:drug effects / Q000502:physiology*; D002614:Chelating Agents / Q000494:pharmacology; D003215:Conditioning, Eyelid / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology; D011689:Purkinje Cells / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D002614:Chelating Agents; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate