Krasnow Institute > Monday Seminars > Abstracts

Plasticity of dendritic excitability

Daniel Johnston
Director, Center for Learning and Memory, University of Texas at Austin

The dendrites of hippocampal pyramidal neurons express numerous types of voltage-gated ion channels. The properties and/or distributions of these channels in the dendrites are very non-uniform and highly regulated. We have investigated long-term changes in voltage-gated channels in hippocampal neurons following the induction of long-term potentiation (LTP) and long-term depression (LTD). We have found that there are activity-dependent, and bi-directional, changes in the intrinsic excitability of these neurons with LTP and LTD. The changes in ion channels occur in parallel to those at the synapse and affect both the local and overall excitability of the neuron. The change in local excitability can increase the probability that a given synaptic input fires the cell while a change in the overall excitability of the neuron may act to stabilize its firing rate following experience dependent plasticity. The underlying mechanisms for these changes, and their implications with respect to certain learning rules, will be discussed.

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