Many phenomena in animal nerve tissue are accompanied by electrical processes. These processes are largely due to mechanisms of nervous activity. They provide special opportunities for studying those aspects of nervous activity which generally do not lend themselves to other research techniques. Conversion of the energy of cell metabolism to a specific neuronal function is responsible for molecular and ionic changes, which are associated with the appearance of electrical potentials and changes in electrical constants of the tissue - its electroconducting and dielectric properties. The electrical potentials that arise in the brain have a varied origin. These include the brief impulses lasting 0.2-3 msec that follow excitation of the neuron and the slower potentials lasting 10-20msec that reflect the processes of local excitation in the cell body and in its dendritic processes. Slow potential oscillations with periods ranging from 50-500 msec are shown in the electrocorticogram (ECoG).