title: Synaptic Specializations Support Frequency-Independent Purkinje Cell Output from the Cerebellar Cortex.
abstract: The output of the cerebellar cortex is conveyed to the deep cerebellar nuclei (DCN) by Purkinje cells (PCs). Here, we characterize the properties of the PC-DCN synapse in juvenile and adult mice and find that prolonged high-frequency stimulation leads to steady-state responses that become increasingly frequency independent within the physiological firing range of PCs in older animals, resulting in a linear relationship between charge transfer and activation frequency. We used a low-affinity antagonist to show that GABAA-receptor saturation occurs at this synapse but does not underlie frequency-invariant transmission. We propose that PC-DCN synapses have two components of release: one prominent early in trains and another specialized to maintain transmission during prolonged activation. Short-term facilitation offsets partial vesicle depletion to produce frequency-independent transmission.
authors.affiliation: Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA.
authors.forename: Josef
authors.initials: J
authors.lastname: Turecek
authors.affiliation: Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA.
authors.forename: Skyler L
authors.initials: SL
authors.lastname: Jackman
authors.affiliation: Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA. Electronic address: wade_regehr@hms.harvard.edu.
authors.forename: Wade G
authors.initials: WG
authors.lastname: Regehr
mesh_terms: D000375:Aging / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D002525:Cerebellar Cortex / Q000378:metabolism* / Q000502:physiology; D002529:Cerebellar Nuclei / Q000378:metabolism / Q000502:physiology; D051379:Mice; D011689:Purkinje Cells / Q000378:metabolism* / Q000502:physiology; D011963:Receptors, GABA-A / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism / Q000502:physiology; D009435:Synaptic Transmission / Q000235:genetics / Q000502:physiology
chemical_list: D011963:Receptors, GABA-A
keywords: Purkinje cells; TPMPA; cerebellum; deep cerebellar nucleus; presynaptic; receptor saturation; recovery from depression; short-term facilitation