Chapter 14 Character and function of specific neurons: a Cajalian perspective

Abstract

Publisher Summary The chemical identification of neurons containing various neuroactive substances and calcium-binding proteins, together with modern tracing methods, confirm to a great extent Cajal's views on the target selectivity of particular cell types in various regions. The hippocampal efferents taking the fimbria route to reach the septum correspond to axons of pyramidal cells of the regio inferior (∼CA3-4), whereas those of the regio superior (∼CAl-2) have both, collateral and terminal branches ramifying in the plexi of the strata oriens, radiatum and lacunosum. Chandelier cells are immunoreactive to parvalbumin further characterized this singular short axon cell, in fact, the only type that escaped Cajal's observational powers. Concerning the intrinsic functional polarization of the neuron, Cajal's ideas, as in most instances, evolved in trying to incorporate his ever-increasing amount of observations. Thus, the so-called “law of dynamic polarization” gave way to the law of axipetal polarization, which included the possibility of propagation of the nerve impulse from the soma to the dendrite, as it occurs in the case of the axon originating from a dendrite at a considerable distance from the soma.