Somatic EPSP amplitude is independent of synapse location in hippocampal pyramidal neurons.
Most neurons receive thousands of synaptic inputs onto widely spread dendrites. Because of dendritic filtering, distant synapses should have less efficacy than proximal ones. To investigate this, we characterized the amplitude and kinetics of excitatory synaptic input across the apical dendrites of CA1 pyramidal neurons using dual whole-cell recordings. We found that dendritic EPSP amplitude increases with distance from the soma, counterbalancing the filtering effects of the dendrites and reducing the location dependence of somatic EPSP amplitude. Dendritic current injections and a multi-compartmental computer model demonstrated that dendritic membrane properties have only a minor role in elevating the local EPSP. Instead a progressive increase in synaptic conductance seems to be primarily responsible for normalizing the amplitudes of individual inputs.
Magee
J C
JC
Neuroscience Center, Louisiana State University Medical Center, 2020 Gravier St., New Orleans, Louisiana 70112, USA. jmagee@lsumc.edu
Cook
E P
EP
D000818:Animals; D048429:Cell Size / Q000502:physiology; D003712:Dendrites / Q000502:physiology* / Q000648:ultrastructure; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D007700:Kinetics; D008959:Models, Neurological; D017966:Pyramidal Cells / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000502:physiology; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D013997:Time Factors
D018091:Receptors, AMPA