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Multiple forms of activity‐dependent intrinsic plasticity in layer V cortical neurones in vivo
Author(s) -
Paz Jeanne T.,
Mahon Séverine,
Tiret Pascale,
Genet Stéphane,
Delord Bruno,
Charpier Stéphane
Publication year - 2009
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2009.169334
Subject(s) - neuroscience , neuroplasticity , plasticity , synaptic plasticity , homeostatic plasticity , motor cortex , nonsynaptic plasticity , electrophysiology , chemistry , premovement neuronal activity , intracellular , biology , metaplasticity , microbiology and biotechnology , stimulation , materials science , receptor , biochemistry , composite material
Synaptic plasticity is classically considered as the neuronal substrate for learning and memory. However, activity‐dependent changes in neuronal intrinsic excitability have been reported in several learning‐related brain regions, suggesting that intrinsic plasticity could also participate to information storage. Compared to synaptic plasticity, there has been little exploration of the properties of induction and expression of intrinsic plasticity in an intact brain. Here, by the means of in vivo intracellular recordings in the rat we have examined how the intrinsic excitability of layer V motor cortex pyramidal neurones is altered following brief periods of repeated firing. Changes in membrane excitability were assessed by modifications in the discharge frequency versus injected current ( F–I ) curves. Most (∼64%) conditioned neurones exhibited a long‐lasting intrinsic plasticity, which was expressed either by selective changes in the current threshold or in the slope of the F–I curve, or by concomitant changes in both parameters. These modifications in the neuronal input–output relationship led to a global increase or decrease in intrinsic excitability. Passive electrical membrane properties were unaffected by the intracellular conditioning, indicating that intrinsic plasticity resulted from modifications of voltage‐gated ion channels. These results demonstrate that neocortical pyramidal neurones can express in vivo a bidirectional use‐dependent intrinsic plasticity, modifying their sensitivity to weak inputs and/or the gain of their input–output function. These multiple forms of experience‐dependent intrinsic changes, which expand the computational abilities of individual neurones, could shape new network dynamics and thus might participate in the formation of mnemonic motor engrams.