Constant potentials differ depending on whether they are detected by polarizable or non-polarizable electrodes. In the first case, the true difference of electric potentials between any regions is recorded, and in the second, the potentials of the electrodes themselves are superimposed on this difference, the magnitude of which depends on the chemical processes occurring at the metal ends of the electrodes. The constant potentials extracted by the polarizable electrodes are studied in detail . In this paper, we consider constant potentials recorded exclusively by non-polarizable electrodes.
In some cases, the constant components of the evoked potentials, which have a relatively small amplitude (hundreds of microvolts) and last up to seconds, are of interest. The nature of such shifts is apparently associated with membrane potentials of a nervous and glial origin. The methodology for registering these potentials can be found in manuals on evoked potentials. The SCP, studied in this manual, is large (of the order of several 59 millivolts), and its shifts occur, as a rule, with more significant changes in the functional state of the body associated with stress, hyperventilation or the use of pharmacological drugs, and not with weak sensory stimulation. The amplitude of such shifts can exceed several millivolts, and the duration is several minutes. These SHP shifts are primarily of metabolic origin and are associated with a change in pH at the BBB boundary .
AMRs are recorded by monopolar and bipolar methods. In bipolar registration, the active and reference electrodes are located on the head above the SCP regions. When monopolar registration, one of the electrodes is located on the head, and the other is in the electrically indifferent region.