[Development of working memory brain organization in young schoolchildren].

In children of 7-8 and 9-10 years old, the ERP components were studied by comparing two non-verbalized visuo-spatial stimuli shown in succession with 1.5-1.8 s interstimulus interval. We found the age-related differences in the specific way (and the extent to which) the cortical areas were involved into the processes of the reference stimulus (the first stimulus in the pair) encoding and into the process of comparing the memory trace against the test stimulus. In both age groups, the sensory-specific N1 ERP component in the visual cortices had larger amplitude during working memory than during free observation. Age-related differences in the processing of the sensory-specific parameters of a stimulus are most pronounced in ERP to the test stimulus: in children of 9-10, the amplitude of N1 component increased significantly in all caudal leads following the earlier increase in P1 component in the inferior temporal and occipital areas. In the children of that age, unlike children of 7-8, the early involvement of ventro-lateral prefrontal cortex becomes apparent. In that area an increase of positivity confined to 100-200 ms post-stimulus is observed. Substantial inter-group differences are observed in the late ERP components that are related to cognitive operations. In children of 7-8, presenting both reference and test stimuli causes a significant increase in the amplitude of late positive complex (LPC) in caudal leads with maximal increase being observed in parietal areas at 300-800 ms post-stimulus. In children of 9-10, one can see some adult-like features of the late ERP components during different stages of the working memory process: in fronto-central areas N400 component increases in response to the reference stimulus, whereas LPC increases in response to the test stimulus. The data reported in this work show that the almost mature functional organization of working memory is already in place at the age of 9-10. However, the extent of the prefrontal cortex (especially its dorsal areas) involvement does not yet match the level of maturity.

[The age-related characteristics of the correlation of involuntary and voluntary analysis during image recognition]. / Vozrastnye osobennosti sootnosheniia neproizvol'nogo i proizvol'nogo analiza pri opoznanii izobrazhenii.

An experimental paradigm was used, based on the stimuli presentation in the absence and presence of the attention, directed to them; it allowed to divide involuntary (automatic) and voluntary (controlled) processing levels of the analysis, functioning parallelly in the process of real image identification. In conditions of this paradigm the regional and hemispheric organization of the evoked electrical activity (ERP and differential curves) was studied in youths aged 16-17 (11 persons) and children aged 7 (15 persons). The analysis of the differential curves revealed periods of negativation and positivation, connected with the automatic (unattended stimuli) and controlled (attended stimuli) analysis of images. Correlation of the identification success and singled out periods of differential curves has shown that in children aged 7 sensory decisions achieved on the automatic level are a significant contribution to the identification of images. Attraction of the attention to the stimulus in children aged 7 intensifies its processing, observed already after making the main decision on the character of the stimulus. In youths the success of identification correlated mainly with the processes at the controlled level; in this case the integrating role of the left frontal area at the final stage of the analysis is singled out.

[The interaction of perception and attention at different stages in individual development]. / Vzaimodeistvie vospriiatiia i vnimaniia na raznykh étapakh individual'nogo razvitiia.

In the study carried out on children aged 10 years (51 persons), subjects aged 16-17 (11) and adults (19) characteristics of the perception and attention interaction were studied by means of electrophysiological parameters analysis (ERP, CNV, EEG) of the process of solution of various visual tasks. It has been shown that adequate brain provision of this process is based in adults both on the functional topographic differentiation and specialization of separate perceptive operations and on the possibility of controlling generalized and local activating influences according to task requirements. In children aged 10, not differing from the adults by the success of the perceptive activity, age peculiarities of its strategy are revealed connected with functional brain organization. Basic distinctive features of children perceptive activity are intensified regional specificity manifested both in responses to relevant and non-relevant stimuli, and excessive generalized activation testifying to incomplete structural-functional maturation of the frontal regions of the cerebral cortex. Increasing functional activity of these structures in ontogenesis provides for the selectivity of perceptive, cognitive and activating processes, adequate to the requirements of the task.