卷 44, 编号 2 (2018)

The paper describes one of the central areas of research of Professor Natal’ya N. Traugott, a famous Russian neurophysiologist. In particular, Prof. Traugott identified the general neurophysiological mechanisms responsible for speech disorders in children with alalia and in adults with aphasia caused by focal brain lesions. Physiological experiments showed that both sensory alalia in children and sensory aphasia in adults are associated with the deficiency of auditory analyzer; such deficiency leads to disorders in the formation of conditional reactions to sounds and sound complexes. Moreover, a general development pattern was identified in the ontogeny of interaction of signal systems and in the degradation of such interaction caused by the lesions of particular analyzers. This finding of Prof. Traugott is very important in both theory of cerebral speech mechanisms and speech therapy practices aimed at speech system development and rehabilitation following cerebral dysfunctions.

This study analyzed specificities in the activity of the neurophysiological mechanisms underlying the organization of active word-derivation processes. The regularities in the reorganization of the spatial structure for the systemic interaction of bioelectrical activity between different cortical areas of the cerebral hemispheres were studied in adult subjects during the test for mental derivation of common root words (i.е., using the modern methods of the so-called “functional connectome” investigations). Сross-correlation and coherent analysis of EEG has shown that the ipsilateral statistical EEG interactions in the left hemisphere, including Broca’s and Wernicke’s areas, were significantly increased in adults during mental derivation of common root words and, simultaneously, the interhemispheric connectivity and the EEG interactions in the right hemisphere were reduced. Comparison of our results with the previous data of verbal activity associated with speech perception and production has revealed significant differences in the degree of involvement of the left and right hemisphere cortical activity in verbal processing. For example, unlike the data of current study, an equal involvement of both hemispheres cortical activity was recorded during the phoneme recognition in auditory perceived words, grammatical and semantic errors in sentences, as well as during mental formation of words from a set of phonemes and sentences from a set of words, which was particularly manifested in the increased of hemispheric interactions, predominantly, in the inferior frontal and temporal areas and the overlapped areas of the temporal, parietal, and occipital cortical zones (TPO) of both hemispheres. Thus, the data obtained in this study indicate the presence of expressed specificities in the lateralization of activity in the neurophysiological mechanisms underlying the processes of active word derivation and inflexion.

The aim of the present study was to investigate the reading mechanisms in adults (27 subjects; mean age, 19.5 ± 0.8 [SD] years) with different levels of written text comprehension using fMRI. The main objective was to analyze the basic brain mechanisms of verbal stimuli perception with and without semantic component during reading discrimination tasks. The BOLD signal changes during WORD and PSEUDOWORD reading comparing to GAZE FIXATION state were estimated using both analysis of whole brain activation and ROIs (structures connected with the brain system providing reading) in two groups of subjects, “good” and “poor” readers. It was revealed that activations were higher in “poor” readers in lingual gyrus, SMG, STG compared to “good” readers during PSEUDOWORD reading. It was supposed, that the strategies of words and pseudowords recognition differed in two groups of readers: “good” readers identified words or pseudowords already at the stage of visual analysis of “word” structure and demonstrated attempts to decode pseudowords (i.e., language lexical zones were not activated); “poor” readers, apparently, tried to read pseudowords using the same strategy as for the words reading referring to the lexicon, and after failure identified pseudowords as meaningless concepts. In that case, activations of both lexical “language” zones and visual word form area (VWFA) were observed.

The article presents empirical data on the possible use of transcranial Doppler sonography as a method for the identification of functional specialization of hemispheres. We investigated intrahemispheric differences in the increase in blood flow velocity indicators during the performance of cognitive tasks with verbal and nonverbal stimuli in 20 healthy right-handed participants and 20 right-handed patients with local unilateral vascular brain lesions. We observed interhemispheric and intrahemispheric differences in blood flow velocity indicators between arteries during the performance of cognitive tasks with different variants of verbal stimuli in all participants. It has been found that one of the hemispheres plays a dominant role in verbal and nonverbal stimulus processing.

The paper presents the results of the study on reading mechanisms in children of primary school age performed using eye tracking. The participants were 36 second-grade pupils. Eye movements were registered when reading a specially developed set of sentences containing words with controlled length and frequency. Neuropsychological assessment and reading of words with regular and irregular spelling were also performed. The results confirm the data of reading analysis obtained in other languages and show that characteristics of eye movements during reading depend on the length and frequency of the word. The results indicate a close relationship between the characteristics of the oculomotor activity and the level of the development of reading skills. Analysis of the relationship of eye movements and neuropsychological assessments of the cognitive abilities of children shows that the executive functions and functions for visuospatial information processing are the most important in the second year of reading aquisition. The role of auditory information processing functions requires further investigation.

Longitudinal analysis of the spectral power of the main EEG bands was performed in the wakeful state with the eyes open and the eyes closed in children with mental disorders at various stages of correction by transcranial direct current stimulation (tDCS). A significant increase in the power of α-rhythm in the parietal-occipital areas and a significant decrease in the slow wave activity in the left frontotemporal areas were observed in the course of the correction process. The data obtained can be considered as the neurophysiological markers of the tDCS effects (formation of age-related EEG parameters in children with mental disorders). The data also prove the relations between the described phenomena and the cortical mechanisms of speech disorders and other psychic processes caused by perinatal CNS disorders.

When studying the dynamics of brain electric activity (BEA) in the course of botulinum toxin (Incobotulinumtoxin A) injections into all hypertonic muscles of 16 patients suffering from post-coma longterm consciousness disorders, BEA changes were observed to start within the first minutes after the first intramuscular injection of botulinum toxin, while not being associated with any pain stimulus response. Despite the diversity of brain lesions in these patients, the dynamics of BEA reorganisation during botulinum toxin therapy showed the presence of pathological sensorimotor integration involving the whole brain in case of long-term consciousness disorders. In our opinion, it is expressed in a pathological state developing in the brain, which affects the polyfunctional capabilities of neurons. This state is unbalanced due to destabilizing effect at the beginning of the reduction by pathological hyperafferentation from muscles and, in principle, can be disrupted at a complete reduction. It is, however, maintained by memory matrix, which manifests itself in the shape of oscillation process during its disruption when the newly build-up BEA is occasionally displaced by the previous one. During the reduction of sensory hyperafferentation, BEA reorganisation initially involved the motor cortex (in 15 out of 16 patients) and then spread to other brain areas, including those responsible for the higher mental functions, vision, and hearing. The first transiently decreased muscle tone (in all patients) and improvement of neurological signs of awareness (in some patients) were observed immediately after injecting all hypertonic muscles with widespread BEA changes. The appearance of high-frequency EEG activity in the frontal areas was considered as a universal marker of an improved functional state of the brain during the disruption of pathological sensorimotor integration even before clinical signs, suggesting neuronal readiness to maintain various activities. In view of data obtained, the first-stage clinical measures in patients with disorders of consciousness should focus on disrupting pathological sensorimotor integration, opening a way for restoring neuronal functional activity, provided that all “pathological afferents” are reduced.

A variety of perceptual features can be used for the successful separation of information flows and higher speech intelligibility. The binaural system based on the spatial allocation of speech signals plays the most important role in attaining this goal. This review discusses how the mechanisms of spatial hearing provide selective attention to a target speech source and promote the recognition of a masked target signal.