Volume 74, Nº 5 (2024)

Information in the brain is encoded by large populations of neurons – neural ensembles. The place cells in the hippocampal CA1 field have become an experimental model for the study of neural ensembles of the brain due to the convenience of research. This review is devoted to the latest studies of place cells in the CA1 field. We consider the principles of encoding space by place cells, mechanisms for controlling the activity of place cells, anatomical and physiological features of place cells in different parts of the CA1 field. Key points: 1. There are rate and phase coding; 2. Dense local connections between pyramidal neurons can provide information processing; 3. Interneurons are involved in the formation of both the rate and phase code of place cells; 4. Pyramidal neurons are anatomically and functionally divided into deep and superficial; 5. Along the dorsoventral axis, the spatial and non-spatial component of information is generalized. The CA1 field has extensive capabilities for signal processing and can implement a computationally complex operation in the cognitive processes of the brain.

Post-traumatic stress disorder (PTSD) is a severe, disabling syndrome that is induced by an extremely powerful negative impact on the people’s psyche. Symptoms of the disease most often do not appear in the entire population of stressed people and not immediately, but after some indefinite period of time. The disease is caused by central, genetic, epigenetic and neurobiological determinants, interactively integrated within the underlying social and natural-anthropogenic context. The simultaneous development of a pathological reaction from the hypothalamic-pituitary-adrenal, sympathoadrenal and immune systems was established. Information on the state of the main biogenic and amino acid neurotransmitters of the central nervous system in PTSD is presented. Researchers are currently focusing on peptide hormones such as brain-derived neurotrophic factor, neuropeptide Y, and leptin, which can be used to diagnose and treat PTSD. An analysis of the literature led to the conclusion that about the characteristics of stress-resistant people and animals very little is still known.

The question of the activity of muscles that provide the realization of imaginary movement is essential in the rehabilitation of motor disorders using neurointerfaces. The literature data on this issue are contradictory. The paper analyzes the EMG activity of the shin and thigh muscles of 40 healthy volunteers when working with a neurointerface based on kinesthetic motor imagery of walking in place and supplemented with the «Biokin» robotic limb movement device (mechanotherapy), activated in case of successful motor imagery. It is shown that working with a neurointerface, on average for subjects, leads to an increase in muscle activity when motor imagery of walking compared to rest, and activation of the mechanical training device (AM) further increases muscle activity, with its effect being more pronounced in the muscles of the leg from which motor imagery of walking begins. The nature of muscle reactions to the task of motor imagery of walking is individual. AM when working with a neurointerface, the number of subjects with pronounced EMG activity increases, as does the number of significant correlations between the activity of the muscles of the lower limbs. Thus, the use of neurointerfaces based on motor imagery of walking and the addition of AM as feedback allows activating the muscles of the lower extremities, which is important in clinical practice in the rehabilitation of movements.

It is known that housing in an enriched environment (EE) prevents the development of anxiety-depressive disorders and cognitive impairment caused by various stresses. In a very limited number of studies on learning and memory in the Morris water maze, pro-inflammatory stress was elicited before the exposure of animals in the EE. In this study, we, for the first time, examined the inverse sequence of interaction between EE and stress; in the first place was the action of the EE, while on the second place – the influence of stress. 40 rats aged 25 to 45 days were placed in the EE and 40 other rats were kept under standard conditions. Pro-inflammatory stress in rats of both groups was induced by injection of a bacterial toxin, lipopolysaccharide LPS, once (acute stress, 350 μg/kg) and repeatedly (chronic, 200 μg/kg) 1 hour before the start of behavioral experiments and during their performance. Control animals were injected with saline at the same volume. Rats of the EE group found the platform faster and swam a shorter distance to it than rats of the standard group. Improvements in behavioral parameters were observed in animals with acute and chronic LPS stress, and in control rats. It should also be noted that the dynamics of learning and the features of the long-term and working memory in rats with acute and chronic LPS were similar, which points to a similar effect of EE on functional changes in the brain activity of rats, regardless of the nature of the subsequent stress. The results obtained indicate the important role of EE in beneficially influencing the behavior of rats when searching for a safe platform.