Neuronal adaptation involves rapid expansion of the action potential initiation site.
Action potential (AP) generation is the key to information-processing in the brain. Although APs are normally initiated in the axonal initial segment, developmental adaptation or prolonged network activity may alter the initiation site geometry thus affecting cell excitability. Here we find that hippocampal dentate granule cells adapt their spiking threshold to the kinetics of the ongoing dendrosomatic excitatory input by expanding the AP-initiation area away from the soma while also decelerating local axonal spikes. Dual-patch soma-axon recordings combined with axonal Na(+) and Ca(2+) imaging and biophysical modelling show that the underlying mechanism involves distance-dependent inactivation of axonal Na(+) channels due to somatic depolarization propagating into the axon. Thus, the ensuing changes in the AP-initiation zone and local AP propagation could provide activity-dependent control of cell excitability and spiking on a relatively rapid timescale.
1] UCL Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK [2] Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Campus de San Juan, Sant Joan d'Alacant, 03550 Alicante, Spain [3].
Ricardo S
RS
Scott
1] UCL Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK [2] Institute of Cellular Neurosciences, University of Bonn Medical School, D-53105 Bonn, Germany [3].
Christian
C
Henneberger
1] UCL Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK [2] [3].
Ragunathan
R
Padmashri
Institute of Cellular Neurosciences, University of Bonn Medical School, D-53105 Bonn, Germany.
Stefanie
S
Anders
UCL Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK.
Thomas P
TP
Jensen
UCL Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK.
Dmitri A
DA
Rusakov
D000200:Action Potentials / Q000502:physiology*; D000222:Adaptation, Physiological; D000818:Animals; D001369:Axons / Q000502:physiology; D055592:Biophysical Phenomena; D003712:Dendrites / Q000502:physiology; D018891:Dentate Gyrus / Q000166:cytology; D005453:Fluorescence; D015640:Ion Channel Gating; D008297:Male; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000378:metabolism; D013569:Synapses / Q000502:physiology
D015222:Sodium Channels