K+ CHANNEL REGULATION OF SIGNAL PROPAGATION IN DENDRITES OF HIPPOCAMPAL PYRAMIDAL NEURONS

Pyramidal neurons receive tens of thousands of synaptic inputs on thei r dendrites. The dendrites dynamically after the strengths of these sy napses and coordinate them to produce an output in ways that are not w ell understood. surprisingly, there turns out to be a very high densit y of transient A-type potassium ion channels in dendrites of hippocamp al CA1 pyramidal neurons. These channels prevent initiation of an acti on potential in the dendrites, limit the back-propagation of action po tentials into the dendrites, and reduce excitatory synaptic events. Th e channels act to prevent large, rapid dendritic depolarizations, ther eby regulating orthograde and retrograde propagation of dendritic pote ntials.