Cortical Spreading Depression: A Model for Studying Brain Consequences of Malnutrition

Abstract

This chapter focuses on the worldwide problem of the neurological impact of nutritional deficiency and how to electrophysiologically study it by analyzing the changes in brain electrical activity. The electrophysiological phenomenon known as spreading depression of the cortical electrical activity or simply “cortical spreading depression” is briefly presented. This phenomenon is an interesting and remarkable reaction produced by the brain gray-matter in response to electrical, mechanical, or chemical stimulation of one point of the tissue. Experimental data on cortical spreading depression obtained under conditions of severe and moderate malnutrition, as well as under favorable nutritional conditions early in life (“overnutrition”) are described and possible underlying mechanisms are discussed. Changes in the propagation features of this phenomenon under normal and altered nutritional conditions are reviewed and confronted with changes studied under the effect of non-nutritional (environmental, hormonal, and pharmacological) factors in studies on developing and adult animals. Over the last two decades, data from several laboratories including ours, on an impressive number of experiments, have shown that the propagation velocity of cortical spreading depression constitutes a good indicator of alterations induced by malnutrition or by other conditions that influence brain developmental and physiological properties. The description of the experimental conditions studied is made in a simple manner and pertinent literature is presented concisely, enabling nonspecialists to understand the text easily. The experimental findings strongly support the conclusion that cortical spreading depression is a useful and interesting tool to electrophysiologically investigate the effects of nutritional changes on brain development and function, enabling also analyzing the interaction between the effects of nutritional and non-nutritional factors.