LTP is accompanied by an enhanced local excitability of pyramidal neuron dendrites

What is it about?

Using a combination of dendritic and somatic whole-cell recordings and calcium imaging in acute hippocampal slices, we show that LTP induction protocols elicit a persistent and local increase in the amplitude of back-propagating action potentials (b-APs) and their associated calcium signals selectively in those dendritic regions where synapses are stimulated. This enhanced dendritic excitability was accompanied with and accounted for by a down-regulation of dendritic outward current - specifically a hyperpolarized shift in the inactivation curve of A-type potassium currents. Such a change in A-type currents produces an increase in steady-state inactivation at resting membrane potentials, which in turn leads to enhanced excitability.

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Why is it important?

This paper reports the intriguing finding that induction of long-term potentiation (LTP) in CA1 hippocampus is accompanied by a local increase in dendritic excitability. The finding provides an important framework for our understanding of dendritic signal processing, integration, and plasticity. It may, for example, represent a new locus for memory storage (namely in the function of ion channels/dendritic excitability) and a substrate for metaplasticity.