572. Schaller KL and Caldwell JH. (2003) Expression and distribution of voltage-gated sodium channels in the cerebellum. Cerebellum 2:2-9.

NeuronCompartmentPropertyConnectivityNotes
Cerebellum Purkinje cellSomaI Na,t.Sensitive to TTX. This generates the impulses that propagate into the axon (Llinas R and Sugimori M, 1980 [guinea pig ]86 ). Simultaneous whole-cell recordings, made from the soma and dendrites rat brain slices, showed that AP evoked by either current pulses or synaptic stimulation of parallel or climbing fibers, always occurred first at the soma and decreased in amplitude with increasing distance into the dendrites. Simultaneous somatic and axonal recordings showed that these action potentials were initiated in the axon (Stuart G and Hausser M, 1994290 ). The kinetics properties of this current were studied using whole-cell recording from dissociated neurons. Unlike other cells, recovery from inactivation was accompanied by a sizeable ionic current. It was suggested that the current flowing during this recovery may depolarize the cells immediately after an AP, promoting the typical high-frequency firing of these neurons (complex spike) (Raman IM and Bean BP, 2001298 ). NaV1.1 is present in the soma and proximal dendrites, NaV1.6 is robustly present in cell bodies and dendrites, and NaV1.7 is absent from the cell (Ahn HS et al, 2011571 >572<>573<).
Cerebellum Purkinje cellProximal equivalent dendriteI Na,t.Simultaneous whole-cell recordings, made from the soma and dendrites rat brain slices, showed that AP evoked by either current pulses or synaptic stimulation of parallel or climbing fibers, always occurred first at the soma and decreased in amplitude with increasing distance into the dendrites. Simultaneous somatic and axonal recordings showed that these action potentials were initiated in the axon. Outside-out patches excised from the soma and dendrites up to about 100um revealed a channel density decreasing with distance from the soma. (Stuart G and Hausser M, 1994290 ). However, in guinea pigs, a combination of high-speed imaging and simultaneous intracellular recordings showed that direct depolarization of the soma or dendrites never caused dendritic [Na+]i increases, suggesting that the climbing fiber-activated [Na+]i changes in the dendrites are due to Na+ entry through ligand-gated channels (Callaway JC and Ross WN, 1997 [guinea pig ]291 ). NaV1.2 is substantially present throughout the dendrites, NaV1.1 is present in the soma and proximal dendrites, NaV1.6 is robustly present in cell bodies and dendrites, and NaV1.7 is absent from the cell (Ahn HS et al, 2011571 >572<>573<).

References
86. Llinas R and Sugimori M. (1980) Electrophysiological properties of in vitro Purkinje cell somata in mammalian cerebellar slices. J Physiol 305:171-95.
290. Stuart G and Hausser M. (1994) Initiation and spread of sodium action potentials in cerebellar Purkinje cells. Neuron 13:703-12.
298. Raman IM and Bean BP. (2001) Inactivation and recovery of sodium currents in cerebellar Purkinje neurons: evidence for two mechanisms. Biophys J 80:729-37.
571. Ahn HS, Black JA, Zhao P, Tyrrell L, Waxman SG and Dib-Hajj SD. (2011) Nav1.7 is the predominant sodium channel in rodent olfactory sensory neurons. Mol Pain 7:32 [Journal] .
291. Callaway JC and Ross WN. (1997) Spatial distribution of synaptically activated sodium concentration changes in cerebellar Purkinje neurons. J Neurophysiol 77:145-52 [Journal] .
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