Vol 74, No 2 (2024)

The article provides a review of experimental studies exploring the nature of neurovisceral interactions through the analysis of heart rate variability at different stages of individual development and within different species. Analysis of heart rate variability is one of the most common and accessible experimental methods to observe aspects of neurovisceral (for example, neurocardiac) interactions. Nonstationary, nonlinear components in the dynamics of inter-beat intervals (periods between adjacent heart beats) reflect the processes of coordination of heart activity with changes in the organization of neural activity, ensuring the current relationship of the individual with the environment. Mathematically, these aspects of heart rate dynamics are expressed in estimates of the complexity, irregularity, entropy, and unpredictability of the time sequence of inter-beat intervals. The dynamics of neurocardiac interactions described in this way are not the same in different species and become more complex in phylogeny. Similarly, in individual development, the dynamics of the heart rate becomes more complex and reflects, among other things, the degree of maturation of certain nervous structures at different stages of ontogenesis. We examined the features of the dynamics of neurovisceral interactions in individual and phylogenetic development within the framework of the system-evolution theory and interpreted them in connection with changes in the structure of individual experience – the characteristics of a set of functional systems actualized in behavior (increasing differentiation of the relationship between the individual and the environment).

In the present study, we analyzed the differential involvement of hippocampal interneurons and pyramidal neurons in the retrieval of associative aversive context memory. For this purpose, we used a model of associative learning in which the formation of a neutral context memory and the subsequent association of this memory with the footshock US during a brief reminder of the context were significantly separated in time. The activation of hippocampal neurons during associative context memory retrieval in this task was addressed by immunohistochemical detection of the immediate early gene c-fos protein. Retrieval of associative context memory was accompanied by an increase in the number of c-Fos-positive cells in the CA1 region, but not in the CA3 region and the dentate gyrus of the hippocampus. Next, a protein marker, the product of the homeobox-containing gene Emx1, was used to specifically identify excitatory neurons, and the marker glutamate decarboxylase, GAD, the product of the GAD1 and GAD2 genes, was used to specifically identify inhibitory neurons. The results of double staining for cell markers and c-Fos protein showed that during retrieval of associative aversive context memory in the CA1 region of the hippocampus, both Emx1-positive excitatory neurons and, less, GAD-positive inhibitory interneurons were activated. At the same time, regardless of the type of behavioral procedure (retrieval of associative context memory, non-associative context memory, or exploration of context, where animals previously received the footshock but did not remember it), the proportion of activated excitatory and inhibitory neurons remained constant, only the number of activated cells of each type changed. Altogether, our results indicate the specific role of hippocampal CA1 neurons in associative context memory and demonstrate that both excitatory and inhibitory neurons are involved in the encoding of such memory.

The hypothalamic-pituitary-adrenal axis (HPA) plays an important role in the mechanisms of adaptation to chronic stress. A model of chronic social defeat stress (CSDS), based on the experience of defeat in daily agonistic interactions, causes the development of a depressive-like state in mice, which is often accompanied by an increase in blood corticosterone levels. In this work, we assessed what changes occur in the central (hypothalamus) and peripheral (adrenal glands) parts of the HPA axis under the influence of chronic social stress, which can affect the regulation of corticosterone synthesis and its level in the blood. The experience of chronic social stress causes an increase in the relative weight of the adrenal glands, an increase in the expression level of Crh gene in the hypothalamus and the expression of the genes for the corticosterone synthesis enzymes Star, Cyp11a1, Cyp11b1 in the adrenal glands. At the same time, in the hypothalamus the expression of Fkbp5 and Nr3c1 decreases and the expression of Crhbp increases, and in the adrenal glands the expression of the Mc2r and Hsd11b1 genes decreases, which is ultimately aimed at reducing the amount of corticosterone secreted by the adrenal glands, and thus limiting the glucocorticoid response. Thus, chronic stress leads to an imbalance of the activating and stabilizing mechanisms of HPA axis regulation and a possible inadequate response to additional stress stimuli.

The work investigates spatial and temporal EEG patterns during real and imagined execution of hand reaching. Six independent sources of electrical activity were identified in the EEG recordings. The sources corresponded to the premotor areas, supplementary motor area, primary motor areas, and posterior parietal cortex. Their activation patterns in the alpha and beta range were studied using a continuous wavelet transform. The main differences between real and imagined movement are found in the activation of primary motor and premotor areas. Asymmetry in activation of primary motor areas was observed only during the imaginary movements. Desynchronization in premotor areas of both the alpha and beta ranges, suggesting their activation, accompanied the imaginary movements throughout their course. On the other hand, hypersynchronization was observed in premotor areas during real movement, which likely corresponds to inhibition, while desynchronization was observed in the latent period, 1.5 seconds before the start of movement. Thus, an imaginary movement bears the features of planning a real movement.

This research is aimed at investigating the characteristics of activity of brain areas that underlie action execution and are modulated by the error detection mechanism under conditions of various potential monetary benefits of manipulative truthful and false actions. It is shown that the implementation of potentially less profitable deceptive actions is associated with a relatively higher level of functional activity of the inferior frontal gyrus, a structure that receives information from structures associated with the error detection mechanism. This effect was revealed in experimental conditions with less reinforced deceptive actions, both in comparison with relatively more rewarded deception, and with manipulative truthful actions, regardless of their reward. Moreover, the increase in the profit of deceptive actions is accompanied by the disappearance of a statistically significant difference in the activity of the ventrolateral prefrontal cortex, which has been observed in the comparison of equally low profitable truthful and false actions. These results indicate a possible mechanism of expected monetary benefit influence on the manipulative decision to lie, according to which, the prefrontal structures underlying control of behavior show less susceptibility to the involvement of the error detection mechanism in maintaining deceptive actions.