Brain Electrochemical Potential Alterations Monitored by Platinum Electrodes in Behaving Animals

Abstract

Brain electrochemical potential (E) variations were recorded by implanted platinum electrodes in waking rabbits in two series of experiments. In the first series including the three groups of rabbits (the 1st—with electrodes, implanted upon the dura mater; the 2nd—with electrodes implanted upon the pia mater and the 3rd—with electrodes implanted in the cortical layer), the time courses of brain E were investigated correlated with the degree of brain damage by electrodes. A number of long-term E fluctuations (of some days) with damped amplitude have been revealed to develop during 5–25 days after the electrode's implantation, after which relatively stable negative values of E were established on the average in electrodes implanted upon the dura materand positive values in electrodes implanted upon the pia mater and in the cortical layer. It was also found that short-term E oscillations (of seconds to minutes) can form in brain alongside the long-term E changes. The probability of short-term E variation occurrence depended both on the degree of brain injury and on the level of specific functional brain stress (level of anxiety), investigated in the second series of experiments.