FUNDAMENTAL EFFECTS OF EPILEPTOGENOUS AGENTS UPON THE CENTRAL NERVOUS SYSTEM

1. The permeability of the cell surfaces for electrolytes was studied in vitro and in vivo by measuring the polarizability of the brain tissue.

2. Agents that produce swelling of the brain by increasing the state of hydration of the brain tissue (e. g., distilled water, alkali) increase the permeability, as shown by the decrease in polarizibility. This is a reversible process, as indicated by the effect of some acids and of hypertonic salt solutions after previous swelling of the brain.

3. These experiments support the view that pathologic processes which call forth swelling of the brain produce an impairment of the cell surfaces in that their density is lowered. The transitory increase in permeability of the cell surfaces that is, according to the modern theories of excitation, an essential part of the excitation process is thus facilitated, and the threshold of the cells for metabolic or other stimuli is lowered. This explains the mechanism by which swelling of the brain increases the convulsive reactivity. Investigations are under way to ascertain as to whether other epileptogenous agents have similar basic effects.