Effects of Acute Ethanol Intoxication on Local Field Potentials in the Rat Lateral Septum

The lateral septum (LS) is an important part of the limbic and reward brain systems; its activity has been associated with the development of different aspects of addiction. Using a stereotaxically inserted semi-microelectrode, we recorded local field potentials (LFPs) from the rat LS under background conditions and after i.p. injection of 2.0 g/kg body mass 15% ethanol (Ethl) solution. The recorded LFPs showed typical 1/f behavior. Acute Ethl intoxication resulted in increases in the spectral power of nearly all frequency LFP ranges, except the beta-1 sub-band. A prominent peak has been detected in the beta-1 sub-band centered at 14.77 Hz. Ethanol intoxication resulted in a shift of this peak toward 13.70 Hz with simultaneous decrease in the power of the above sub-band. Powers of most LFP ranges/subranges under conditions of the above intoxications demonstrated increments, most intense for delta, beta-2, gamma-high, and epsilon (ultrafast, >90 Hz) oscillations. Changes in the relatively highfrequency LFP components are assumed to reflect Ethl-induced modifications of the activity of local LS neuronal ensembles, while those of low-frequency (delta) oscillations are probably related to global modulation of the activity of the entire brain. It is supposed that the observed changes caused by acute Ethl intoxication may reflect mainly intensification of GABA-mediated signaling.