Fast changes in default and control network activity underlying intraindividual response time variability in childhood: Does age and sex matter?

Abstract

Intraindividual response time variability (RTV) is considered as a general marker of neurological health. In adults, the central executive and salience networks (taskpositive networks, TPN) and the default mode network (DMN) are critical for RTV.Given that RTV decreases with growing up, and that boys are likely somewhat behind girls with respect to the network development, we aimed to clarify age and sex effects.Electroencephalogram was recorded during Stroop-like test performance in 124 typically developing children aged 5-12 years. Network fluctuations were calculated as changes of current source density (CSD) in regions of interest (ROIs) from pretest to 1-s test interval. In boys, TPN activation (CSD increase in ROIs included in the TPN) was associated with lower RTV, suggesting a greater engagement of attentional control.In children younger than 9.5 years, higher response stability was associated with the predominance of TPN activation over DMN activation (CSD increase in ROIs included in the TPN > that in the DMN); this predominance increased with age, suggesting that variability among younger children may be due to network immaturity. These findings suggest that the TPN and DMN may play different roles within the network mechanisms of RTV in boys and girls and at different developmental stages.

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“…Conversely, reduced default mode network deactivation is believed to result in attention lapses that produce inconsistency in motor output ( 14 ). Our finding of an association between elevated Step RT-IIV with CLEI (males ≥0.282 and females ≥0.301) is consistent with evidence for the interpretation of high RT-IIV as a behavioral correlate of neural impairment ( 20 , 27 – 29 , 39 ).…”

“…In addition to the generation of fast and accurate responses, efficient brain processing produces relatively consistent response times over multiple trials ( 37 , 38 ). Low intraindividual variability (IIV) among stimulus responses (e.g., standard deviation or coefficient of variation) has been demonstrated to provide meaningful information about brain processing efficiency that is not derived from a measure of central tendency (e.g., RT-Avg) ( 20 , 28 , 29 , 35 , 39 – 41 ).…”