This work aims to study the event-related potentials (ERPs) during the cyclic movement of sound stimuli and to choose the optimal model for neuronal coding of azimuthal motion. The ERPs elicited by the cyclic motion of sound stimuli were investigated under conditions of dichotic stimulation. Stepwise or linear motion patterns were created by cyclic changes in the interaural time difference (ITD), which changed by 800 & micro;s, and then returned to its initial value. Statistically significant ERPs were evoked by the motion onset and by the repeated changes of direction (sound turns) only in the case of a stepwise ITD pattern. The amplitude of the responses consistently depended on the angular position of the turning points relative to the head midline. These results support a two-channel model for encoding spatial information in the auditory cortex. ERPs evoked by motion offset indicated that spatial attention and sensory memory were involved in the preconscious perception of cyclic motion.
The influence of neuroinflammation on the reconsolidation of fear memory is poorly studied, using only acute but not the remote effects of intoxication. In the present work, we investigated the influence of remote pro-inflammatory lipopolysaccharide (LPS) stress on the reconsolidation and extinction of fear memory in adult male Wistar rats. On the 3rd and 5th PND, during the critical period of postnatal ontogenesis, the rats received subcutaneous injections of LPS (50 mu g/kg) or saline. At 120 PND, the rats acquired a fear conditioning by the use of three pairings of tone presentations and shock. Twenty-four hours after training, one group of rats was reactivated in the same context and by a single tone presentation (Re+), while the other group remained in the home cages, (Re-). A day later, in retention test 1, the freezing reaction was measured in all groups. After test 1, the groups underwent extinction for two days with 10 tones on each day, followed by retention test 2. In test 1, the contextual memory of the Re+ vs. Re-saline groups were impaired as opposed to cue memory. The early LPS stress equalized the level of freezing of both Re+ and Re-groups, indicating that early neuroinflammation impairs the updating of the contextual fear memory. The differences in the level of freezing between the Re+ and Re-groups persisted during extinction and in test 2. The extinction of the LPS group was slower than that in the SAL group. Thus, remote neuroinflammation impairs the process of memory updating and extinction of conditioned fear.
In the study behavioral and neurophysiological indices of processing emotional facial expressions of anger, fear, joy, surprise, disgust and sadness in girls with single panic attacks (PA) and girls without panic attacks (norm), all the students of the medical university, were compared. In the PA group, facial expressions of anger and fear were recognized with an increased reaction time compared to joyful ones; in the norm group, differences associated with the type of expression were absent. Compared with the norm, in PA, a clear increase in the amplitude of the occipital components P100 and P200 to emotional faces was recorded, indicating increased exogenous attention to the facial emotions, with a more pronounced response to anger compared to other emotional expressions. An increase in the amplitudes of the P100 and P200 components in the ERP of the temporal regions in PA indicates increased activity of the limbic formations, which also leads to increased ascending attention to facial expression. In the frontal cortex, in PA the amplitude of the ERP components is increased, that is combined with signs of insensitivity of the early negativity of N90 to the type of emotional expressions. The results indicate an altered state of the attention network and limbic-prefrontal complex in a nonclinical group of girls with isolated panic attacks.
The plastic changes in auditory perception during classes using the complex music and singing education method by D.E. Ogorodnov were studied. A group of 65 children, in addition to the school music program, additionally studied using the Ogorodnov's method five times a week, and the control group of 29 people took music.jessons.according to the regularschool programs. The subjects aged 7-10 years performed the auditory attention test in the ODDBALL paradigm twice with an interval of 4 weeks. To analyze the obtained event-related potentials (ERPs), the blind source separation method was used, based on the approximate joint diagonalization of the covariance matrices calculated for the group ERPs. Decomposition of the group ERPS into hidden components made it possible to isolate the component that reveals the specific effect of training. As our studies have shown, children from the control group show adaptation to auditory stimulation carried out twice during a month. This adaptation was manifested in a significant decrease in the amplitude of the temporal component of the ERP during the repeated examination. In the group of children who studied using the Ogorodnov's method, such adaptation was not found.
Mice of two strains, differing by the relative brain weight (LB and SB) displayed differential behavioral effects after 7-day exposure to 50 mg/kg of memantine injections, the non-competitive NMDA-rec antagonist. Memantine increased the exploration behavior in LB mice as well as their reaction to novelty, while SB mice demonstrated the activation of behavior after the control saline injections. The number of newly developed neuronal elements in the hippocampal subgranular zone of dentate gyrus in LB (but not SB) mice subjected to memantine was higher in comparison to controls. In the intact samples of mouse strains used in this work no significant behavioral differences were found, which accentuated the genotype-dependent effects of memantine injections.
This study is devoted to the investigation of neural correlates of attentional template formation in categorical search. The categorization process plays a crucial role in optimizing information processing and storage in working memory. Categories are divided into subordinate, basic and superordinate levels, which determine the degree of specificity and clarity of representation. Attentional templates contain attributes that define the target, such as color, shape, or size, and are activated in preparation for retrieval. The aim of the study was to examine the difference in the neurophysiological mechanisms of attentional template formation under the influence of verbally given categories of basic and superordinate levels. The category level (basic or superordinate) was manipulated, possible changes in N2pc (N2-posterior- contralateral component) and CDA (contralateral delay activity) amplitudes were recorded as well as behavioral measures. Behavioral results were consistent with other studies of visual search and categorization. The CDA component related to visual working memory load showed no statistically significant differences, whereas the N2pc component showed classic results for visual search paradigm-it changed with lateralization and with the number of stimuli, but no effect of category level was revealed. This study showed that there are differences at the behavioral level in a categorical visual search task, but they are absent for the CDA and N2pc components amplitudes-the effect may be manifested in oscillations; a block design is probably not suitable for assessing changes in CDA amplitude, verbal presentation of categories does not lead to differences in amplitude.
Histological and electron microscopic studies of dentate fascia neurotransplants in the somatosensory region of the rat neocortex were performed. It was shown that mature nerve tissue developed in the transplants with reproduction of the organotypic characteristics of differentiated neurons and glial cells. Particular attention was paid to the study of the cellular organization of the boundary between the transplanted and neocortical tissues (interface) as well as the possibility of neuronal processes growing through it. The leading role in the integrative process belonged to different subpopulations of astrocytes. Mature protoplasmic and fibrous astrocytes, as well as astrocytic precursors, and ependymal cells were identified at different sites of the interface. The cellular composition of the border influenced the degree of integration of the transplants with the adjacent brain, ranging from maximum integration in the astrocytic type of border to limited exchange of axonal and dendritic processes in the ependymal type. Fibrous astrocyte processes accompanied and guided bundles of axons and dendrites through interface. The only barrier to the growing nerve processes were the interface regions, into which large blood vessels penetrated from the pia mater.
Musical improvisation, especially in jazz, is a unique form of creative process that requires active interaction Between different brain networks. Unlike the performance of pre-Tearned musical parts, improvisation is characterized by the reduced functional connectivity between the central executive network (ECN) and the default mode network (DMN), allowing bottom-up processes to guide creative behavior. This phenomenon, known as hypofrontality, contributes to reduced cognitive control and facilitates spontaneous idea generation. The aim of this review is to investigate the neural mechanisms underlying musical improvisation. Findings have shown that cognitive control is reduced during improvisation, allowing musicians to generate new musical ideas with minimal interference from executive functions. At the same time, performing pre-learned music requires higher levels of cognitive appraisal and control, which is associated with higher functional connectivity of the ECN and DMN. Of particular interest was the finding that the same neural networks are activated during imaginative improvisation as during real performance, which emphasizes the importance of self-referential processes in creativity. The findings support the hypothesis that improvisation activates unique neural mechanisms that facilitate spontaneous creativity and the free flow of ideas.
Periodic hypoxia includes periods of low oxygen content, interspersed with periods of reoxygenation. Periodic hypoxia is usually associated with pathological conditions and is considered as a negative stimulus leading to disorders of cognitive functions, the cardiovascular system, respiration and metabolism. It is the most important pathophysiological element of sleep apnea syndrome, which is accompanied by the development of inflammation and oxidative stress. On the other hand, periodic hypoxia, unrelated to sleep apnea, has a positive or negative effect on the body, depending on the intensity, duration and number and frequency of hypoxic exposures. In medicine, periodic hypoxia is used to improve health and enhance performance and is a non-pharmacological treatment for a number of diseases. The goal of the present review is to summarize clinical and experimental data on the effect of periodic hypoxemic hypoxia on the adult body. Special attention is paid to the effect of periodic hypoxia on cognitive functions. The review discusses the molecular mechanisms by which periodic hypoxia can trigger a cascade of intracellular reactions leading to either beneficial or pathological effects
The present paper describes backward conditioned connections (BCC) as a universal principle of brain activity. The first section analyzes the historical view of the problem: the discovery of the phenomenon of BCC, the rules and regularities of its manifestation (the role of the ratio of the strength of the paired stimuli, the duration of the conditioned stimulus, the time following after the unconditioned stimulus before the start of the conditioned stimulus, the number of pairings, and other factors). In the second section, some hypotheses explaining the formation, functioning, and role of bilateral conditioned connections in the process of organizing holistic behavior are considered. And the last section describes the current state of the problem of reverse US-CS connections-the study of 2nd-order conditioned reflexes, sensory preconditioning, stimulus equivalence analysis, and the role of context. The importance of dopamine in BCC and the role of these connections in memory reconsolidation are considered. Attention is paid to modern neurochemical, electrophysiological, optogenetic and other studies of the BCC.
Over the past decade, the main focus in functional magnetic resonance imaging (fMRI) studies on the structural and functional organization of the human brain has shifted from functional segregation, i.e., the functional specialization of individual brain structures, to functional integration, i.e., the collective activity of the brain systems. Currently, the most common type of fMRI study is the resting-state functional connectivity studies, due to the relative ease of obtaining and statistically analyzing data. At the same time, growing attention is paid to dynamic changes of functional connections during task performance. In this review, we briefly describe the nature of functional connectivity measured using fMRI, review existing task-modulated functional connectivity methods, and provide practical recommendations for choosing a statistical analysis method and planning the fMRI task design. In conclusion, we will discuss the significance and prospects of studying task-modulated functional connectivity for fundamental research into the systemic organization of the human brain in health and pathology.
The effect of priming with an animal image versus an object image on basic-level and superordinate-level categorization parameters was investigated in 19 healthy young subjects. For both basic-and superordinatelevel categorization, priming with an animal image, as more evolutionarily significant, causes an increase in the amplitude of early N50 negativity to the salient stimulus in temporal areas, indicating an increase in attention. The effect of the animal prime on behavioral responses and on later potential components depends on the categorization level. In basic-level categorization there is an increase in motor reaction time, and in superordinate-level categorization there is an increase in accuracy. During basic-level categorization with animal primes, an increase in the amplitudes of the occipitotemporal P130 and frontal N130 components is accompanied by a decrease in central late positivity (LP). The increased P130 and N130 amplitudes may indicate an increased difficulty in separating significant and insignificant visual information due to a shift of attention to the prime. The decrease in LP amplitude is probably related to difficulties in processing the stimulus at the stage of comparing it with the category description stored in memory. During superordinatelevel categorization, the animal prime, compared to the object prime, induces increases in the amplitude of the frontal P50, occipital P130, and central LP components. Presumably, the increase in P50 reflects the implicit categorization of the prime by its low-frequency description, which reduces prime-stimulus interference at later stages of processing. The increase in LP amplitude reflects the facilitated stage of matching the stimulus to the categorization description, as well as an increase in endogenous attention during processing of the animal prime.
Cognitive aging is a multifactorial process that manifests itself in the deterioration of attention, memory, learning ability, decreased speed of information processing and decision-making, language capabilities, and impairment of executive functions. The mechanisms underlying these processes are not fully understood. The literature contains data on age-related changes in the structure, metabolism and activity of the brain, the occurrence of inflammatory processes and oxidative stress, as well as the influence of genetic and environmental factors. Although considerable evidence has been found of natural changes in the aging brain, they are not clearly integrated. At the same time, understanding the mechanisms of these processes will allow developing strategies for the prevention and treatment of cognitive impairment in old age to achieve a full quality of life at any stage. In neurophysiology, a distinction is made between "healthy aging" with minor changes in the cognitive function, and "pathological aging", aggravated by the development of neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), characterized by a sharp decline in mental abilities, up to dementia. Changes in the brain of patients with AD and PD differ from those observed during normal aging. However, the mechanisms by which aging increases the risk of developing AD and PD remain unclear. To slow down/prevent the processes of cognitive decline, it is important to understand what compensatory mechanisms of the brain (cognitive reserve) exist that increase resistance to cognitive aging. This review briefly describes the main neural and network changes observed in healthy older people and leading to certain difficulties in memorization, problem solving and decision making. The main focus is on the consideration of the putative causes of cognitive aging. Part of the review concerns the contribution of aging mechanisms to the development of neurodegenerative diseases such as AD and PD. Data on the existing cognitive reserve and ways to maintain it are also provided.
Exploratory activity is a vital form of behavior influenced by the habitat and individual experiences of animals. To assess the roles of these factors, we studied exploratory behavior in an identical setting among three rodent species that differ in their ecological niches, navigation characteristics, and levels of individual experience: wild animals from natural populations - bank voles (Clethrionomys glareolus) and the herb field mouse (Sylvaemus uralensis)-and C57BL/6J laboratory mice. Exploratory behavior was measure in a standardized open field test. To evaluate the influence of environmental novelty, animals had four sessions of empty open field exploration explored followed by four sessions in an enriched open field. Expert annotation of the behavioral patterns revealed that the animals engaged in 11 specific behavioral acts to explore the empty arena and 22 types of acts in the enriched arena. Notably, we identified specific behavioral acts in either wild rodents or laboratory mice. Bank voles displayed significantly less exploratory activity compared to the mouse species, which showed only slight differences in exploratory behavior. A key factor influencing the exploratory activity of the compared species was the enrichment of the arena with objects. The addition of objects not only increased the overall exploratory activity of the animals but also altered the structure of their exploratory behavior. Contrary to the initial hypothesis, the factor of environmental novelty had the least influence on behavior, with effects varying depending on specific behavioral forms and manifesting only in combination with other factors. The results reveal complex and nonlinear relationships among the factors determining rodent behavior in the open field task, which should be considered in analyzing the neural bases of this behavior and interpreting exploratory behavior in natural conditions.
There is increasing evidence that the gene network with common regulatory elements that affect their expression may be involved in the manifestation of various diseases. We have previously identified 12 genes associated with neurodegenerative diseases (kcne2, gart, tmem50b, il10rb, ifnar2, urb1, grik1, usp16, ltn1, cyyr1, app, jam2), which carry in their introns the recombination product between LINE1 and BovB retrotransposons with sites of homology to different microRNAs. They also maintain high evolutionary conservatism of genetic linkage in mammals, including platypus (chromosome 17) and human (chromosome 21). In order to clarify the possible functional relationships that protect the genetic linkage, an in silico analysis of the specific expression functional features was performed. The results showed their involvement in fundamental biological processes of cell life support and the close relationship between the proteins encoded by the genes. Thus, an excess of the app gene product reduces or blocks the processes of cell excitability. A reduction in cell excitability can lead to inhibition of the expression of genes encoding proteins involved in intercellular interactions, protein synthesis, purine synthesis, activation of cell ageing, cell death, and an increase in the activity of anti-inflammatory processes. We suggest that the close linkage of the 12 genes is maintained in the evolutionary process due to this relationship and the presence of the same regulatory network elements in them, which may simultaneously correct their expression. Thus, the study of the synteny of genes closely related to neuropathologies can contribute to a deeper understanding of the genetic mechanisms regulating higher nervous activity.
This article presents a comparison of changes in molecular markers of systemogenesis related to behavioral motivation: approach versus avoidance, differing in their stress levels. We conducted an immunohistochemical study of brain-derived neurotrophic factor (BDNF) in the medial prefrontal cortex of adult Long-Evans rats. Two groups were trained in a bar-pressing task: 1) to activate a food dispenser and obtain food (approach); 2) to terminate a shock and avoid pain (avoidance). The avoidance group showed significantly fewer BDNF-immunopositive cells in the prelimbic and infralimbic prefrontal cortex compared to the approach group. Furthermore, BDNF levels correlated with individual differences in anxiety and exploratory activity. We conclude that the medial prefrontal cortex is involved in both approach and avoidance behaviors, but to a significantly lesser extent in avoidance. The potential role of stress-induced neuroinflammation in these differences is discussed.
From the standpoint of the system-evolutionary approach we analyzed the regional specificity of brain support of behavior when solving the task of distinguishing short time intervals. The "Yes-No" task for distinguishing short time intervals was used (N = 10 who learned to distinguish short time intervals). When analyzing 19 scalp electrodes of EEG by methods of cluster and factor analysis, 2 groups of electrodes were formed: frontal-central and parietal-occipital. The general configuration of the selected components of the ERP is shown, which is consistent with the ideas of the general cerebral character of behavior. The differences between the groups of electrodes consisted in amplitude-temporal characteristics. In this connection, the systemic psychophysiological significance of the regional specificity of brain processes is discussed.
Cognitive abilities in neurodegenerative discases begin to alter much carlier than the main clinical pathomorphological core of the disease develops, while patients for many years do not demonstrate pronounced clinical manifestations amid active functioning compensatory mechanisms. Subsequently. the leading symptom complex formed against the background of decompensation becomes practically insensitive to modern drug treatment. In this regard, the search for carly manifestations of cognitive and neurological changes that could serve as reliable markers of the development of the neurodegenerative process, is a relevant task of diagnosing these diseases. Currently, in practical work, psychiatrists and neurologists mostly use blank cognitive tests for screening diagnostics of cognitive disorders based on questionnaires with scaled results, sensitivity of which is high for the stages of advanced disease, but is not enough for the stages of prodrome cognitive impairment. Therefore, the creation of a tool for objective screening of early stages of cognitive impairments, combining efficiency and case of use, is an important and modern direction of neuroscience. Suggested review aims to analyze and summarize available data on the change in reaction speed at the onset of neurological diseases. The need for modernization of neuropsychological diagnostics with the help of possible integration of sensorimotor tests with computer technology is revealed. It should improve the reliability and accessibility of the screening assessment. It is shown that, apart from simple reaction (SRT), such reaction indicators as reaction time variability (RTV), choice reaction time (RTT) and the dynamic of reaction time are the objective and independent markers of efficiency of information processing by the nervous system.
This pilot study aimed to investigate brain functional activity and connectivity using functional magnetic resonance imaging (MRI) and clectroencephalography (EEG) in Tibetan monks during meditation. Themeditative practice was based on Buddhist techniques requiring focused attention and the "dissolution" of mental imagery. Three monks participated in the experiment, two of whom underwent two meditation sessions. Data analysis revealed changes in the connectivity of the default mode network, salience network, and sensorimotor network during meditation compared to the resting state. An increase in alpha rhythm and a decrease in delta rhythm (EEG) were observed. Joint (MRI-EEG analysis identified a relationship between brain activity and the dynamics of alpha and delta rhythms. The results indicate that meditation significantly influences brain activity and may serve as a neurotherapeutic technique to enhance cognitive and psyclao.cmotional functions.
The study examines the neurophysiological correlates of confirmation bias in the context of vaccination using fixation-related potentials (FRPs). A methodological approach integrating eye tracking and electroencephalography (EEG) was employed in a laboratory experiment, enabling the synchronization of eye movement data with the brain's bioelectrical activity. Participants read texts about vaccination containing positive, negative, and neutral statements, while their reactions were recorded under conditions of congruence and incongruence between the valence of the text and the implicit component of their attitude, measured via the Implicit Association Test. The findings revealed significant differences in neurophysiological responses, including increased potential amplitudes in incongruent conditions for the P200, P300, N350, and N400 components. These responses indicate the activation of selective attention and enhanced perceptual stimulus processing (P200), reallocation of attentional resources and the emergence of cognitive dissonance (P300), emotional categorization (N350), and semantic, including valence-related, mismatch processing (N400). The results underscore the high sensitivity of FRP methods to the cognitive and emotional aspects of information perception. The proposed methodological approach enhances the ecological validity of the study, offering promising opportunities for investigating implicit cognitive processes in naturalistic text perception settings.
