Mitochondria-endoplasmic reticulum contacts (MERC) are known as one of the key regulators of many cell functions. In particular, MERC effects on the mobility and morphology of mitochondria, exchange of calcium and lipids between organelles, and participates in the processes of autophagy and apoptosis that are crucial for neuronal development. MERC can influence the functioning of the neurotrophic factor BDNF through the activation of the Sigma-1 receptor. That points to the presence of feedback i.e. itself BDNF influence on the structural characteristics of MERC. At the same time, the effect of chronic stimulation of BDNF or blockade of TrkB receptors on an ability to form contacts between mitochondria and ER is different and depends on cellular compartment.
|9 EFFECT OF CHRONIC EXOGENOUS STIMULATION.pdf||800.25 KB|
In probabilistic conditions, people choose low-payoff alternatives on some trials, thus failing to maximize their payoffs. We suggest that such behavior implicates exploration of task rules by choosing risky options instead of exploiting more rewarding alternatives. We hypothesized that exploration would affect brain responses to feedback. Further, a shift to exploration develops gradually and, therefore, a decision to make an exploratory choice may be observed on trials preceding risky choices. We investigated beta power (16–30 Hz) in the magnetoencephalographic data from 62 healthy participants performing a two-choice probabilistic gambling with monetary gains and losses. The effects were found at 600–800 ms after feedback onset in frontal, central and occipital brain regions. On trials preceding risky choices we identified a decrease in beta power which implies a change in decision-making strategy and a shift towards cognitive flexibility and exploration. An increase in beta power during risky decisions indicates that reward learning mechanisms are implicated. Increases in beta power following losses in risky choices indicates at the process of updating the internal representation of the task. In summary, current findings reveal that the outcomes of exploratory trials are processed differentially, while there is no evidence of such processing on exploitatory trials. This corroborates the hypothesis that exploratory choices represent active probing into the surmised task rules. Current findings also suggest that the processing of outcomes preceding the exploratory trials is altered in such a way that subjects override their intention to use the utility model and reset their behavioral strategy.
|8 BETA-BAND POWER PREDICTS EXPLORATORY CHOICES.pdf||499.58 KB|
Plastic changes in the neurons of the amygdala during learning in fear conditioning and their contribution to the modifications of behavior are well known, but the impact of hippocampal neurons in this behavioral task is not well studied to date. Recently a novel technique for simultaneous recording of calcium signal in multiple neurons in the brain of awake freely moving animals by miniature fluorescent microscope (miniscope) was developed. With the use of the miniscope, we have investigated neuronal activity in the CA1 area of hippocampus during memory formation and a recall in the task of contextual fear conditioning and correlated it with recorded mice behavior. Three epochs during learning were analyzed in mice behavior and brain activity: 120 s before, 2 s during, and 30 s after the electric shock. Memory retrieval was induced by placement of the animals for 180 s in the same context 24 h and 48 h after learning. The total amount of the neurons recorded in three mice was 507 during learning and 401 during memory retrieval. The patterns of neuronal activity were analyzed and discussed.
|7 INVESTIGATION OF CA1 NEURONAL ACTIVITY DURING.pdf||455.91 KB|
Cognitive status and EEG in the theta, alpha, and beta ranges were studied using cluster analysis by discrete optimization in patients with cardiovascular disease in the preoperative period of coronary artery bypass grafting. The cognitive status was measured by Mini-Mental State Examination (MMSE) scale, and an integral indicator of cognitive status (IICS) formed on the basis of complex testing the indices of visual-motor responses, attention, and memory. The new method of clustering the EEG power and the cognitive status made it possible to distinguish groups of patients differenced by cognitive reserves. The IICS better differentiates groups than MMSE. The factors of age and education were decisive only in specific groups. The clusters characterized by the most represented cognitive reserves according to the higher both MMSE and IICS indicators included less pronounced activation of the cortex according to more power of the theta, alpha, and less beta rhythm. Patients with supposedly minimal reserves are differed by a low level of cognitive status, as well as education level together with higher activation state of the cortex. The third type of clusters was distinguished by an unstable composition due to the variability of EEG indicators in it, mostly cortical activity at the alpha1 frequencies. The EEG neurophysiological approach, together with cognitive screening and proposed clustering analysis, could be helpful in understanding mechanisms of cognitive reserves and identify the risk factors of postoperative cognitive dysfunction in patients with brain cardiovascular damage.
|6 DIFFERENTIATION OF COGNITIVE STATUS IN PATIENTS.pdf||542.11 KB|
The information influence in the modern globalizing world is a serious challenge to the security of any state. This article presents the results of an experimental study of the way the modern Internet media affect the cognitive attitudes of individuals on the example of two leading international TV channels – RT and BBC. In order to conduct this study our team developed an experimental plan for the psychophysiological recording of deformation of cognitive attitudes under the external informational influence. The study was conducted at the Department of Psychophysiology of the Lobachevsky State University of Nizhny Novgorod from March to May 2018. The experiment was conducted on twenty-one (21) volunteers aged from nineteen to thirty-six, the average age of the group being twenty-four. Since the largest audience of modern communication networks is the younger generation, they became the focus of the study. The authors analyzed the deformations of the cognitive attitudes of individuals to identify distinctive features of these processes.
|5 MODELLING THE INFLUENCE OF RT AND BBC.pdf||440.21 KB|
The extracellular matrix plays an important role in brain function. Recent findings suggest that disruption of hyaluronan-based extracellular matrix can cause seizure-like activity (Vedunova et al., 2013). Epilepsy can be characterized by an excessive influx of Ca2+ ions through (Ca2+) – permeable AMPA receptors, which may, in certain circumstances, contribute to seizures. Ca2+ – permeability of these receptors is dependent on RNA-editing of pre-mRNA transcript of GluA2 subunit at the Q/R site. Regulation of this process is carried out by a special nuclear enzyme, ADAR2 (Adenosine Deaminase Acting on RNA-2). Thus, the study of the principle of operation of this enzyme can contribute to understanding the mechanism of epileptogenesis.
|4 HYALURONIDASE-DEPENDENT CHANGES.pdf||380.06 KB|
Gamma band oscillations (25 - 70 Hz) play an important role in processing of information by neocortical neurons. In simple cells of the cat's visual cortex, it was previously shown that strength of gamma oscillations is modulated by the membrane potential oscillations at the temporal frequency of the stimulus. More recently, theoretical studies using a conductance-based neuronal model have shown that this coupling significantly improves visual stimulus encoding. Due to the availability of a broad range of genetic tools, mice had recently become an important experimental subject for research in various fields of neuroscience, including visual physiology. It has been suggested that gamma oscillations in the mouse visual cortex play a minor role in visual processing due to the lack of specialized neurons that take part in generating gamma oscillations. Here we show, using patch clamp recording from simple cells in the visual cortex of anesthetized mice, that the strength of gamma oscillations is modulated by the phase of stimulus-induced oscillations during visual stimulation with moving gratings. In addition, using patch clamp recording from mouse visual cortex neurons in slices, we demonstrated benefits of gamma activity modulation for encoding of slow sinusoidal signals into sequences of action potentials. Thus, the phenomenon of amplitude modulation of gamma oscillations by temporal frequency of stimulus, originally described in the visual system of cats, may represent a universal mechanism that improves encoding of visual information which is present even in animals with a relatively poorly developed visual system, such as mice.
|3 MODULATION OF THE AMPLITUDE OF GAMMA-BAND.pdf||606.55 KB|
Emotion regulation is a popular research topic in social, clinical, cognitive psychology, and neurophysiology. Event-related potentials (ERPs) studies have high temporal resolution and are therefore conventionally used in emotion research to study the patterns of emotion processing. Advances in digital technologies are promoting neuro-psychological research of emotion and attention in virtual reality (VR). In this work, for the first time, we investigated how the presented emotional facial expressions in VR modulate ERP components in conditions of different combinations of passive or active attention and random or linear presentation sequence. We found the higher amplitude of the C1, N170, P2, P3, P4 ERP components in the condition of active attention compared to passive attention during the random presentation of emotional 3D facial expression. During the linear presentation of emotional 3D facial expressions, a statistically significant difference was found only for the C1 ERP component in conditions of both passive and active attention. We proved that the P2 ERP component represents the perception of positive and negative 3D facial expressions encoding the emotional valence of the stimuli. We also found no statistically significant difference in latency of ERP components between passive and active attention to emotional 3D facial expressions.
|2 ERP CORRELATES OF EMOTIONAL FACE PROCESSING.pdf||859.47 KB|
Spontaneous activity is known to be a characteristic feature of the vast majority of the neocortical principal cells including neurons of the primary sensory areas. The question of how spontaneous activity interacts with perception and encoding of sensory information remains open. In the present study, pyramidal neurons of the mouse primary visual cortex were recorded extracellularly under urethane anesthesia and simultaneous single-channel EEG recording was performed. To evaluate orientation and direction selectivity of the recorded neurons, mice were presented with visual stimuli consisting of moving sinusoidal gratings of different orientations displayed on a monitor. We noted quite regular bursts of generalized brain activity that were manifested in the recorded neuron as bundles of action potentials accompanied with a distinctive EEG pattern. Clearly, whenever such spontaneous activity shows up during visual stimulation, it is considered as noise, which significantly compromises the characteristics of the neuron’s measured visual response. To eliminate this effect, we developed a machine learning-based algorithm that enables to identify EEG predictors of generalized spontaneous activity and then to exclude spontaneous (i.e. not evoked by visual stimulation) action potentials from the recording. Our algorithm was shown to reliably detect action potentials that have been caused by generalized brain activity. Removal of action potentials of this origin from extracellular recordings obtained during visual stimulation allows for a more adequate estimation of parameters of neuronal receptive fields, in particular their orientation selectivity.
|1 DETECTION OF SPONTANEOUS ACTION POTENTIALS.pdf||583.4 KB|
This work shows the in vivo effect of the bioactive triterpenoid betulonic acid on the liver of C57BL/10 mice and the functioning of the mitochondria of this organ. We have found that betulonic acid has no significant effect on the histological parameters of the mouse liver, as well as on the biochemical parameters of the blood serum of the studied animals. At the same time, betulonic acid has demonstrated mitochondrial targeting. Betulonic acid has shown a decrease in the functional activity of mitochondria, especially in the case of their energization with succinate, a substrate of complex II of the respiratory chain of organelles. Treatment with betulonic acid has no effect on the resistance of mouse liver mitochondria to the induction of a calcium-dependent MPT pore. On the other hand, we have revealed the antioxidant effect of betulonic acid associated with a decrease in the rate of H2O2 generation in the mouse liver mitochondria. The paper discusses the possible use of betulonic acid as a mitochondria-targeting agent.
|8 In vivo Effect of Betulonic Acid on the State of Liver Tissue.pdf||733.91 KB|