Sodium channels amplify spine potentials.
Dendritic spines mediate most excitatory synapses in the brain. Past theoretical work and recent experimental evidence have suggested that spines could contain sodium channels. We tested this by measuring the effect of the sodium channel blocker tetrodotoxin (TTX) on depolarizations generated by two-photon uncaging of glutamate on spines from mouse neocortical pyramidal neurons. In practically all spines examined, uncaging potentials were significantly reduced by TTX. This effect was postsynaptic and spatially localized to the spine and occurred with uncaging potentials of different amplitudes and in spines of different neck lengths. Our data confirm that spines from neocortical pyramidal neurons are electrically isolated from the dendrite and indicate that they have sodium channels and are therefore excitable structures. Spine sodium channels could boost synaptic potentials and facilitate action potential backpropagation.
Araya
Roberto
R
Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA.
Nikolenko
Volodymyr
V
Eisenthal
Kenneth B
KB
Yuste
Rafael
R
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism*; D004594:Electrophysiology; D051379:Mice; D008810:Mice, Inbred C57BL; D015222:Sodium Channels / Q000378:metabolism*; D013569:Synapses / Q000187:drug effects; D013779:Tetrodotoxin / Q000494:pharmacology
D015222:Sodium Channels; D013779:Tetrodotoxin