Between Cognitivity and Neuropathies: Neuroimaging of the Effects of GABAergic Modulation of the Hippocampus and Prefrontal Neocortexis by Normalized Brain Electrograms

Abstract

A comparative analysis conducted across the entire range of normalized brain electrograms (NBE) revealed the selective effect of gamma-aminobutyric acid (GABA) derivatives in the hippocampus and frontal pole of the neocortex. A signifi cant similarity in the level of activation of these brain regions was revealed under the action of glutamine and, particularly, gabapentin. For gabapentin, the activity of the hippocampus is more comparable to that in the anterior suprasilvius gyrus. Under the action of pregabalin, NBE revealed a similarity between the hippocampus and the proreal gyrus, with a more pronounced activity being registered in the range of 1–10 Hz. The NBE activity in the anterior suprasilvian gyrus was lower than that in the proreal gyrus. Under the action of phenibut, the activity of the hippocampus was higher than that of the prefrontal cortex across the 30–40 Hz range; however, under the action of aminalon, this phenomenon was observed for all the analysed rhythms. The predominant effect of GABA derivatives on the high-frequency components of the γ-rhythms of NBE was established. The most pronounced activation effects in γ-rhythms were characteristic of aminalon, while the most pronounced effects of deprimation were characteristic of gabapentin. The overall picture of the γ-rhythm activity was similar under the administration of glutamine, pregabalin and phenibut, as well as being generally close to the background level. The effects of glutamine and pregabalin in the analysis of NBE showed similarities across the frequency ranges of about 40–44 Hz and 60–64 Hz. The effects of pregabalin, gabapentin, and phenibut were similar across the frequency range of about 52–62 Hz. In the high-frequency γ-rhythms, gabapentin, pregabalin and phenibut were characterized by peaks in the range of 44–50 Hz, 40–55 Hz and 35–40 Hz, respectively. Aminalon showed no similarities with other GABA derivatives and was characterized by an extremum in the γ-rhythm at a frequency of about 41 Hz. Using instrumental methods for assessing cognitive behaviour and the mathematical analysis of NBE, the signifi cant role of the intercalary neurons (basket cells) of the hippocampus and prefrontal cortex in the implementation of glutamate and GABA effects was established. It was confi rmed that GABA derivatives function as the main mediator of intercalary neurons in the systemic activity of the brain. The maximum values of NBE under the action of all the GABA derivatives under study coincide with the pharmacodynamic and pharmacokinetic parameters of these drugs. A comparative analysis of the effects of glutamate and all the studied GABA derivatives revealed the greatest similarity of the former with phenibut. Aminalon, being a synthetic analogue of GABA, differs from all other drugs under study by the highest activation of the general level of NBE. The effects of neuroimaging refl ect the properties and nature of the effect of drugs on cognitive functions, intra-centre relations of the brain and higher nervous activity. New mechanisms of the systemic action of GABA derivatives were studied. The obtained results confi rm that the normalized electrographic activity of various parts of the brain can be used to identify certain physiological and pathogenetic mechanisms of the most important functions of the brain and their disorders. Activation of the GABAergic stress-limiting system can be considered as one of the promising methods for the selection of approaches to preventing and treating diseases associated with neurogenic and psychogenic factors.