The Cortical Neuron as an Electrophysiological Unit

Cellular physiological studies from all areas of the brain have revealed that a rich assortment of ionic channels combine variously in the soma-dendritic membranes of different neurons to produce a diversity of firing types; the cortex is no exception. To add a dynamic dimension to our concept of the neocortical circuit, we must consider the distinctive input-output characteristics of different circuit elements and the diverse ionic channel types that determine them. This chapter briefly reviews the different firing types of neocortical neurons and summarizes the properties of the ionic currents that have been identified in cortex. It also considers mounting evidence that the elaborate dendrites of neocortical neurons are not merely passive accumulators of synaptic input but rather that they also possess functionally significant active properties.