Dendritic Ih ensures high-fidelity dendritic spike responses of motion-sensitive neurons in rat superior colliculus

Endo T, Tarusawa E, Notomi T, Kaneda K, Hirabayashi M, Shigemoto R, Isa T. 2008. Dendritic Ih ensures high-fidelity dendritic spike responses of motion-sensitive neurons in rat superior colliculus. Journal of Neurophysiology. 99(5), 2066–2076.

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Endo, Toshiaki; Tarusawa, Etsuko; Notomi, Takuya; Kaneda, Katsuyuki; Hirabayashi, Masumi; Shigemoto, RyuichiIST Austria ; Isa, Tadashi
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that generate Ih currents are widely distributed in the brain and have been shown to contribute to various neuronal functions. In the present study, we investigated the functions of Ih in the motion-sensitive projection neurons [wide field vertical (WFV) cells] of the superior colliculus, a pivotal visual center for detection of and orientating to salient objects. Combination of whole cell recordings and immunohistochemical investigations suggested that HCN1 channels dominantly contribute to the Ih in WFV cells among HCN isoforms expressed in the superficial superior colliculus and mainly located on their expansive dendritic trees. We found that blocking Ih suppressed the initiation of short- and fixed-latency dendritic spike responses and led instead to long- and fluctuating-latency somatic spike responses to optic fiber stimulations. These results suggest that the dendritic Ih facilitates the dendritic initiation and/or propagation of action potentials and ensures that WFV cells generate spike responses to distal synaptic inputs in a sensitive and robustly time-locked manner, probably by acting as continuous depolarizing drive and fixing dendritic membrane potentials close to the spike threshold. These functions are different from known functions of dendritic Ih revealed in hippocampal and neocortical pyramidal cells, where they spatiotemporally limit the propagations of synaptic inputs along the apical dendrites by reducing dendritic membrane resistance. Thus we have revealed new functional aspects of Ih, and these dendritic properties are likely critical for visual motion processing in these neurons.
Publishing Year
Date Published
2008-05-01
Journal Title
Journal of Neurophysiology
Volume
99
Issue
5
Page
2066 - 2076
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Endo T, Tarusawa E, Notomi T, et al. Dendritic Ih ensures high-fidelity dendritic spike responses of motion-sensitive neurons in rat superior colliculus. Journal of Neurophysiology. 2008;99(5):2066-2076. doi:10.1152/jn.00556.2007
Endo, T., Tarusawa, E., Notomi, T., Kaneda, K., Hirabayashi, M., Shigemoto, R., & Isa, T. (2008). Dendritic Ih ensures high-fidelity dendritic spike responses of motion-sensitive neurons in rat superior colliculus. Journal of Neurophysiology. American Physiological Society. https://doi.org/10.1152/jn.00556.2007
Endo, Toshiaki, Etsuko Tarusawa, Takuya Notomi, Katsuyuki Kaneda, Masumi Hirabayashi, Ryuichi Shigemoto, and Tadashi Isa. “Dendritic Ih Ensures High-Fidelity Dendritic Spike Responses of Motion-Sensitive Neurons in Rat Superior Colliculus.” Journal of Neurophysiology. American Physiological Society, 2008. https://doi.org/10.1152/jn.00556.2007.
T. Endo et al., “Dendritic Ih ensures high-fidelity dendritic spike responses of motion-sensitive neurons in rat superior colliculus,” Journal of Neurophysiology, vol. 99, no. 5. American Physiological Society, pp. 2066–2076, 2008.
Endo T, Tarusawa E, Notomi T, Kaneda K, Hirabayashi M, Shigemoto R, Isa T. 2008. Dendritic Ih ensures high-fidelity dendritic spike responses of motion-sensitive neurons in rat superior colliculus. Journal of Neurophysiology. 99(5), 2066–2076.
Endo, Toshiaki, et al. “Dendritic Ih Ensures High-Fidelity Dendritic Spike Responses of Motion-Sensitive Neurons in Rat Superior Colliculus.” Journal of Neurophysiology, vol. 99, no. 5, American Physiological Society, 2008, pp. 2066–76, doi:10.1152/jn.00556.2007.

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