Volume 73, Nº 1 (2023)

The review is devoted to the analysis of studies aimed at studying second-order visual filters as a mechanism for preattentive grouping of local visual information by striate neurons (first-order filters). The development of ideas about possible mechanisms for combining primary visual features is analyzed, with the emphasis on studies of the properties of second-order filters. The questions of spatial organization and principles of interaction of filters of the first and second orders are considered. The results indicating the multichannel nature of the pooling mechanism and possible relationship between the frequency and orientation settings of the filters of the first and second order are described. A model for organizing filters of the second order is presented, possible neurophysiological correlates of these mechanisms are analyzed, role of the second-order mechanisms in visual perception is considered.

The aim of the study was to compare the spectral characteristics of theta and alpha frequency bands of the resting-state EEG between groups of subjects with different performance of subsequent joint sensorimotor activity in dyads. The study involved 26 men who, in 13 pairs, performed “Columns” trainings with biofeedback from EMG signals from the flexor muscles of the leading hand. According to their performance, the subjects of each pair were assigned to one of 2 groups: “winners” or “losers”. A higher spectral power of the theta rhythm of the EEG with closed eyes was found in the group of “losers” in comparison with the group of “winners” in the frontal, central and temporal zones of the cortex. The “winners” showed a higher level of spectral power of the EEG alpha rhythm with the eyes closed, especially in the alpha-2 frequency range in all 8 zones. The effectiveness of individual and joint training correlated negatively with the theta power and positively with the power of the EEG alpha rhythms in the closed-eyed state.

The effectiveness of brain-computer interface (BCI) control and the success of imagination of movement of the upper and lower extremities were evaluated by the accuracy of recognition of EEG signals (classification accuracy) when imagining movements of the hands, feet and locomotion during 10-day training of 10 volunteers. Averaged data of all the volunteers revealed, that, on the first day of training, the classification accuracy is higher when imagining locomotion than foot movements, on the second day – hands than locomotion, on the fifth day – feet than hands. The average values of classification accuracy when imagining movements of the hands and feet increase by the 3rd day of training, further changes are specific depending on which movement is imagined. When learning the imagination of locomotion, the accuracy of classification does not significantly change. An assessment of the dynamics of individual changes in the accuracy of classification according to linear trends showed that in three participants, training led to an increase in the accuracy of classification (of the hand movements and locomotion – in one subject, of feet – in two subjects); in other three participants – to decrease (of the movements of the hands and locomotion – in one subject, of the locomotion – in the second subject, of feet – in the third). The four participants, as well as the sample average, had no significant changes. The results are discussed in terms of changes in the activity of brain structures during learning and depending on the type of imaginary movements.

Perception of color by human and nonhuman primates is a complex problem, which is studied not only by neurophysiology, but also by neighboring fields of science such as psychophysiology, psycholinguistics, and even philosophy. With neurophysiology as a starting point, I review contributions of adjacent fields in understanding of the primates’ color space encoding. All known at the moment neurophysiologic mechanisms of color perception by primates are reviewed and a hypothetical way of color stimuli processing is proposed, suggesting at a final stage involvement of conceptual (gnostic) neurons encoding only colors of visual stimuli.

A decrease of taurine in hippocampus of the line of rats with pendulum movements (PM), predisposed to audiogenic epilepsy, was shown. Taurine (aminoethanesulfonic acid) is known to be an anticonvulsant drug. The aim of the present work was to verify the predictive validity of taurine in rats with pendulum movements (PM). In neonatal period the exogenous taurine administration did not influence a convulsive activity at the age of 1.5 and 3 months in PM rats. The increase in the number of audiogenic seizures after taurine injections was found in adolescent period in 1.5 months and in prolonged point – in 3 months. The number of abortive seizures decreased under acute injection of taurine in adult PM rats, but the level of ictal and postictal indicators restored one month later, at the age of 4 months. Obtained results indicate the absence of effect of taurine administered to rats in the neonatal age, while at the long-term scale, the rats showed the increasing seizure activity under the action of taurine in adolescent period and confirm the predictive validity of this drug in adult PM rats.

Suppression of glycolysis in the rat hippocampal formations was induced by daily intracerebroventricular injection of 2-deoxy-D-glucose for 10 days. Using electron microscopy, a disturbance of morphological interactions of axonal terminals of granular neurons with perisynaptic astrocytic processes was found. At the same time, both the determinant ultrastructural characteristics of giant synapses and two types of functional contacts (asymmetric chemical active zones with dendritic spines and symmetric adhesive junctions with dendrites) were retained. However, they showed morphological signs of a weakening of synaptic processes, which were expressed in a decrease in the number of intraterminal active zones, clustering of synaptic vesicles, and their removal from neurotransmitter release sites. Compared to the norm, an increase in the number of small mitochondria with an electron-dense matrix and the evidence of initiation of glycogen synthesis in the form of glycosomes were found in the giant terminals. The data obtained indicate that the giant synapses of the hippocampal mossy fibers are a plastic, self-correcting system that is able to function by adapting its own bioenergetic metabolism, when brain glycolysis is suppressed.

Since the 1950s, the dominant paradigm in the cognitive sciences has been cognitivism, which emerged as an alternative to behaviorism, and predominantly views cognitive processes as various kinds of “computations” similar to those performed by the computer. Despite significant advances made in the last quarter of the 20th century within this paradigm, it does not satisfy many scientists because it could not adequately explain some features of cognitive processes. Connectionism, which emerged somewhat later, recognizes the role of computational processes, but as their basis considers a neural network, which is a much better model of brain functioning than Turing-type computations. Neural networks, unlike the classical computer, demonstrate robustness and flexibility in the face of real-world problems, such as increased input noise, or blocked parts of the network. They are also well suited for tasks requiring the parallel resolution of multiple conflicting constraints. Despite this, the analogy between the functioning of the human brain and artificial neural networks is still limited due to radical differences in system design and associated capabilities. Parallel to the paradigms of cognitivism and connectionism, the notions that cognition is a consequence of purely biological processes of interaction between the organism and the environment have developed. These views, which have become increasingly popular in recent years, have taken shape in various currents of the so-called enactivism. This review compares the theoretical postulates of cognitivism, connectionism, and enactivism, as well as the predictive coding paradigm and the free energy principle.