title: Cholinergic neuromodulation changes phase response curve shape and type in cortical pyramidal neurons.
abstract: Spike generation in cortical neurons depends on the interplay between diverse intrinsic conductances. The phase response curve (PRC) is a measure of the spike time shift caused by perturbations of the membrane potential as a function of the phase of the spike cycle of a neuron. Near the rheobase, purely positive (type I) phase-response curves are associated with an onset of repetitive firing through a saddle-node bifurcation, whereas biphasic (type II) phase-response curves point towards a transition based on a Hopf-Andronov bifurcation. In recordings from layer 2/3 pyramidal neurons in cortical slices, cholinergic action, consistent with down-regulation of slow voltage-dependent potassium currents such as the M-current, switched the PRC from type II to type I. This is the first report showing that cholinergic neuromodulation may cause a qualitative switch in the PRCs type implying a change in the fundamental dynamical mechanism of spike generation.
authors.affiliation: Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, California, United States of America.
authors.forename: Klaus M
authors.initials: KM
authors.lastname: Stiefel
authors.forename: Boris S
authors.initials: BS
authors.lastname: Gutkin
authors.forename: Terrence J
authors.initials: TJ
authors.lastname: Sejnowski
mesh_terms: D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology*; D051379:Mice; D017966:Pyramidal Cells / Q000187:drug effects* / Q000502:physiology*; D014793:Visual Cortex / Q000166:cytology*
chemical_list: D002217:Carbachol; D002794:Choline