ACTIVE PROPERTIES OF NEURONAL DENDRITES

Dendrites of neurons in the central nervous system are the principal s ites for excitatory synaptic input. Although little is known about the ir function, two disparate perspectives have arisen to describe the ac tivity patterns inherent to these diverse tree-like structures. Dendri tes are thus considered either passive or active in their role in inte grating synaptic inputs. This review follows the history of dendritic research from before the turn of the century to the present, with a pr imary focus on the hippocampus. A number of recent techniques, includi ng high-speed fluorescence imaging and dendritic patch clamping, have provided new information and perspectives about the active properties of dendrites. The results support previous notions about the dendritic propagation of action potentials and also indicate which types of vol tage-gated sodium and calcium channels are expressed and functionally active in dendrites. Possible roles for the active properties of dendr ites in synaptic plasticity and integration are also discussed.