Abstract
Long-term synaptic modification is not the exclusive mode of memory storage, and persistent regulation of voltage-gated ion channels also participates in memory formation. Intrinsic plasticity is expressed in virtually all neuronal types including principal cells and interneurons. Activation of synaptic glutamate receptors initiates long-lasting changes in neuronal excitability at presynaptic and postsynaptic side. As synaptic plasticity, intrinsic plasticity is bi-directional and expresses a certain level of input-specificity or cell-specificity. We discuss here the nature of the learning rules shared by intrinsic and synaptic plasticity and the impact of intrinsic plasticity on temporal processing.
Highlights
Long-lasting plasticity of chemical synaptic transmission is usually considered as the main mechanism accounting for information storage in the brain
While many ion channels are regulated in parallel [61], two inhibitory channels have recently retain attention: Kv1 channels located in the axon that determine spike threshold and intrinsic excitability [62], and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels located in the dendrites that dampens all depolarizing events such as excitatory postsynaptic potential (EPSP)
positive basket cells (PV-BC) exhibit potentiation of intrinsic excitability (IE) mediated by the downregulation of Kv1 channel activity and induced by synaptic activation of metabotropic glutamate receptor subtype 5 [73] (Figure 4a)
Summary
Long-lasting plasticity of chemical synaptic transmission is usually considered as the main mechanism accounting for information storage in the brain. Synapse-specific changes in transmission from a large array of inputs appears appealing for maintaining a high computational capacity in the brain This appears not to be the whole story and many other factors involved in the transfer of neuronal information occupy today a key position in functional plasticity. We will discuss new expression mechanisms of graded persistent firing, a form of short-term plasticity that may account for working memory. Graded firing: a cellular analog of working memory Working memory is an ephemeral retention of information whose neurobiological substrate can be seen as a stimulus-specific modulation of neural activity that lasts until a new stimulus is presented (Figure 1a). The inversion of the Na+/ Ca2+ exchanger activity by accumulation of intracellular Na+ has been proposed to account for persistent firing in www.sciencedirect.com
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