Control of submillisecond synaptic timing in binaural coincidence detectors by K(v)1 channels.
Neurons in the medial superior olive process sound-localization cues via binaural coincidence detection, in which excitatory synaptic inputs from each ear are segregated onto different branches of a bipolar dendritic structure and summed at the soma and axon with submillisecond time resolution. Although synaptic timing and dynamics critically shape this computation, synaptic interactions with intrinsic ion channels have received less attention. Using paired somatic and dendritic patch-clamp recordings in gerbil brainstem slices together with compartmental modeling, we found that activation of K(v)1 channels by dendritic excitatory postsynaptic potentials (EPSPs) accelerated membrane repolarization in a voltage-dependent manner and actively improved the time resolution of synaptic integration. We found that a somatically biased gradient of K(v)1 channels underlies the degree of compensation for passive cable filtering during propagation of EPSPs in dendrites. Thus, both the spatial distribution and properties of K(v)1 channels are important for preserving binaural synaptic timing.
Mathews
Paul J
PJ
Section of Neurobiology and Institute for Neuroscience, University of Texas at Austin, Austin, Texas, USA.
Jercog
Pablo E
PE
Rinzel
John
J
Scott
Luisa L
LL
Golding
Nace L
NL
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001703:Biophysics; D001933:Brain Stem / Q000166:cytology; D003712:Dendrites / Q000502:physiology; D004546:Elapid Venoms / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005849:Gerbillinae; D066298:In Vitro Techniques; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology*; D051637:Shaker Superfamily of Potassium Channels / Q000378:metabolism*; D013569:Synapses / Q000502:physiology*; D013997:Time Factors
D004546:Elapid Venoms; D051637:Shaker Superfamily of Potassium Channels; C020273:dendrotoxin