Dendritic Morphology and Function

Abstract

This chapter will cover briefly what we know about the morphological and functional characteristics of dendrites, with a particular focus on the most abundant neuron of the neocortex, the pyramidal neuron.

First, this chapter will describe generally the dendritic diversity within the brain, after which it will focus on the cerebral neocortex and on the major neocortical neuronal type, the pyramidal neuron. In particular, this chapter will concentrate on the role of dendritic spines – tiny protrusions that cover the dendrites of pyramidal neurons and which are the receiving site of excitatory transmission – in information processing and storage in the brain. Dendritic input excitability will be discussed at the spine and branch levels in an attempt to describe the diversity in the input/output properties of pyramidal neurons. Some provocative results about the role of spines as biochemical and electrical compartments and the implications for synaptic integration and plasticity will be reviewed. In addition, this chapter will review different forms of dendritic computation and its implication in synaptic plasticity and in the hierarchical processing of information in the cerebral cortex. Finally, some of the theoretical foundations of how passive steady-state and transient electrotonic potentials spread in dendrites, and the biophysical factors that govern the electrotonic spread of potentials in the dendritic arbor of a neuron, will be described.