title: Dendritic mechanisms controlling the threshold and timing requirement of synaptic plasticity.
abstract: Active conductances located and operating on neuronal dendrites are expected to regulate synaptic integration and plasticity. We investigate how Kv4.2-mediated A-type K(+) channels and Ca(2+) -activated K(+) channels are involved in the induction process of Hebbian-type plasticity that requires correlated pre- and postsynaptic activities. In CA1 pyramidal neurons, robust long-term potentiation (LTP) induced by a theta burst pairing protocol usually occurred within a narrow window during which incoming synaptic potentials coincided with postsynaptic depolarization. Elimination of dendritic A-type K(+) currents in Kv4.2(-/-) mice, however, resulted in an expanded time window, making the induction of synaptic potentiation less dependent on the temporal relation of pre- and postsynaptic activity. For the other type of synaptic plasticity, long-term depression, the threshold was significantly increased in Kv4.2(-/-) mice. This shift in depression threshold was restored to normal when the appropriate amount of internal free calcium was chelated during induction. In concert with A-type channels, Ca(2+) -activated K(+) channels also exerted a sliding effect on synaptic plasticity. Blocking these channels in Kv4.2(-/-) mice resulted in an even larger potentiation while by contrast, the depression threshold was shifted further. In conclusion, dendritic A-type and Ca(2+) -activated K(+) channels dually regulate the timing-dependence and thresholds of synaptic plasticity in an additive way.
authors.affiliation: Department of Neuroscience, University of Minnesota, Minneapolis, USA.
authors.forename: Cuiping
authors.initials: C
authors.lastname: Zhao
authors.forename: Lang
authors.initials: L
authors.lastname: Wang
authors.forename: Theoden
authors.initials: T
authors.lastname: Netoff
authors.forename: Li-Lian
authors.initials: LL
authors.lastname: Yuan
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D017774:Long-Term Potentiation / Q000502:physiology*; D036881:Long-Term Synaptic Depression / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism*; D017966:Pyramidal Cells / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D051672:Shal Potassium Channels / Q000378:metabolism*; D013997:Time Factors
chemical_list: D024681:Potassium Channels, Calcium-Activated; D016194:Receptors, N-Methyl-D-Aspartate; D051672:Shal Potassium Channels; D002118:Calcium