Purkinje cell synapses target physiologically unique brainstem neurons.
The cerebellum controls motor learning via Purkinje cell synapses onto discrete populations of neurons in the deep cerebellar nuclei and brainstem vestibular nuclei. In the circuitry that subserves the vestibulo-ocular reflex, the postsynaptic targets of Purkinje cells, termed flocculus target neurons (FTNs), are thought to be a critical site of learning. Little is known, however, about the intrinsic cellular properties of FTNs, which are sparsely distributed in the medial vestibular nucleus. To identify these neurons, we used the L7 promoter to express a tau-green fluorescent protein fusion protein selectively in Purkinje cells. Fluorescent Purkinje cell axons and terminal boutons surrounded the somata and proximal dendrites of a small subset of neurons, presumed FTNs, in the medial vestibular nucleus. Targeted intracellular recordings revealed that FTNs fired spontaneously at high rates in brain slices (mean, 47 spikes/sec) and exhibited dramatic postinhibitory rebound firing after the offset of membrane hyperpolarization. These intrinsic firing properties were exceptional among brainstem vestibular nucleus neurons but strikingly similar to neurons in the deep cerebellar nuclei, indicating a common role for intrinsic firing mechanisms in cerebellar control of diverse behaviors.
Sekirnjak
Chris
C
Systems Neurobiology Laboratories, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
Vissel
Bryce
B
Bollinger
Jacob
J
Faulstich
Michael
M
du Lac
Sascha
S
D000200:Action Potentials / Q000235:genetics / Q000502:physiology; D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000502:physiology*; D002452:Cell Count; D002525:Cerebellar Cortex / Q000166:cytology / Q000502:physiology; D002529:Cerebellar Nuclei / Q000166:cytology / Q000502:physiology; D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000235:genetics; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011689:Purkinje Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D019076:Transgenes; D016875:tau Proteins / Q000235:genetics
D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; C091104:Purkinje cell protein L7; D011993:Recombinant Fusion Proteins; D016875:tau Proteins; D049452:Green Fluorescent Proteins