Federal State Institution of Science Institute of Physiology SB RAMS, Novosibirsk, Russia.
The aim of study was to identify individual differences of EEG-reactions and behavioral responses forthe attention and motor control tasks of primary school children. 56 students of both genders between the ages of 6-8 years participated in the study. EEG was registered in the P300 paradigm when subjects received the target (20%, press of button) or non-target (80%, ignore) tones. There were presented two experimental conditions - 1. Recognition of monophonic signals with different frequencies; 2. Recognition of polyphonic signals. Also, all children were tested by the stop-signal paradigm (SSP), when they pressed a button after the stimulus onset or stopped already prepared motion after a visual stop-signal was presented. Registration of brain activity was carried out in the EEG amplifier NeuroScan, USA with 64 leads, with a sampling rate of 500 Hz.
Analysis of behavioral data revealed that over 75% of children showed more mistakes in mono- than that polyphonic stimulation. Depending on the quality of performance in the test with monophonic stimuli, children were divided into the groups who had the good faith (Regular), chaotic (Chaotic) or mixed behavior (Semichaotic). Children from the group "Chaotic" also showed declining of the recognition quality and increasing of reaction time for recognition of visual images in the SSP.
At the polyphonic stimulation, the P300 peak in the frontal cortical areas was detected after the target signal onset, which was not in response for non-target signal. At the monophonic stimulation, the P300 peak was not observed in the frontal areas for any of the signals, but was observed in the parietal regions as response to both types of signals. Intergroup comparison showed that children from the "Regular" group had the frontal P300 peak to the target stimulus, both for monophonic and polyphonic conditions. Children from the "Semichaotic" group in polyphonic stimulation showed a shift of the P300 peak to temporal cortical regions, and in monophonic condition they had no the P300 peak to the target stimulus. Children from the "Chaotic" group in polyphonic stimulation showed no frontal P300 peak, and in monophonic stimulation they had a negative peak in the left temporal area (Broca's area). In the SSP, the largest amplitude of alpha-beta desynchronization was observed for children from the "Regular" group, and the lowest –for children from the "Chaotic" group.