Electrical and calcium signaling in dendrites of hippocampal pyramidal neurons

This review discusses recent data regarding the different types of voltage-gated Na+, Ca2+, and K+ channels in dendrites of CA1 pyramidal neurons and their function for synaptic integration and plasticity. Na+ and Ca2+ channels are uniformly distributed throughout the dendrites, although Na+ channels in the soma and proximal dendrites differ in their inactivation properties from Na+ channels in more distal regions. Also, different regions of the neuron express different subtypes of Ca2+ channels. K+ channels are unevenly distributed, with the distal dendrites expressing a more than fivefold greater density of a transient A-type K+ channel than proximal regions. These K+ channels exert profound control over the excitability of the pyramidal neurons and the spread of synaptic potentials throughout the dendrites. The ways in which the active properties of dendrites may contribute toward the induction and maintenance of long-term synaptic plasticity are discussed.