The EEG alpha rhythm frequency dynamics during the auditory perception of actions and its relation to intelligence level in children aged 7-10 years

A number of studies have shown the possibility of taking the EEG individual alpha peak frequency (IAPF) as an informative neurophysiological indicator of the overall cognitive efficiency of the human brain. The main goal of the present work was to study the IAPF reactivity in primary school age children in the process of auditory perception of sounds accompanying familiar instrumental movements, and to measure its hypothesized correlation to the verbal and non-verbal intelligence development. The effects of gender and age of children on these interrelations have also been estimated. We analyzed the data pertaining to the sample of primary school children aged 7-10 years (62 subjects). To assess possible age-related effects, the sample of children was additionally divided into two groups aged 7-8 years (24 boys and10 girls) and 9-10 years (14 boys and 14 girls). During the experiment, the subject and the experimenter sat at the adjacent places, with a monitor and a computer mouse (CM) placed on the table in front of each of them. A video showing the CM section of the experimenter’s table was displayed on the monitor screen in front of the subject. Experimental tasks comprised a series of stages (30 s each) including the conditions of a passive visual fixation on the video image of a motionless CM, execution of self-paced circular right-hand movements with CM, observation of similar movements produced by the experimenter, real-time imitation of the experimenter’s movements, wakeful rest with eyes closed, and auditory perception of familiar sounds accompanying the CM movements produced by the experimenter (subject’s eyes still closed). In the context of the present study, we analyzed the EEG dynamics in subjects during the two final stages with eyes closed: wakeful rest (WR) and auditory perception (AP) of familiar CM movements produced by the experimenter. The area of interest in the present study was the electrical activity of the laterally located parietal (P3, P4) and occipital (O1, O2) EEG electrodes. IAPF values were calculated for each of them within 7-13 Hz frequency range and averaged for the sum of them for the two corresponding experimental stages. The reactivity of the alpha rhythm frequency was calculated for each subject separately as the difference between the values of the dominant alpha rhythm frequency in two situations: the auditory perception of instrumental movements and the wakeful rest. Positive values of the frequency reactivity indicated its increase under condition of auditory perception of movements, and negative values - its decrease. The intelligence development levels of the participants were assessed with the help of the Wechsler test for children (WISC). In the context of the present study, the verbal and non-verbal intelligence scores were analyzed separately. We can conclude that in the primary school age children, the individual frequency of the parieto-occipital alpha rhythm in boys does not differ significantly between the groups aged 7-8 and 9-10 years. In girls, in the older group this indicator has a significantly higher value (See Table 1). For children aged 7-10 years, a significant positive correlation was identified between IAPF and non-verbal intelligence score. No connection with verbal intelligence has been found (See Fig. 1). The condition of auditory perception of sounds accompanying familiar instrumental actions evokes the decrease in the parieto-occipital alpha rhythm frequency in the majority of primary school age children, which is most characteristic for the groups of girls aged 9-10 years (See Table 2). A relatively small percentage of children (~ 18%) who demonstrated an increase in the frequency of the parieto-occipital alpha rhythm under condition of auditory perception of familiar instrumental actions, are characterized by lower scores of nonverbal intelligence, relative to their peers (See Fig. 2). Thus, nonverbal intelligence development can be related to the individual developmental characteristics of neural network oscillators, which can be reflected in children as multidirectional reactions in alpha rhythm frequency.