Neural Mechanism Of Response Inhibition In School-age Children

Early school-age is the second stage of rapid development of executive functions（EF）.EFs of children show rapid development from school-entry（6-9 years old）to 9years old.As one fundamental EF,response inhibition develops rapidly and individual differences of EF among children emerges during this period.Studies revealed that multiple regions of prefrontal cortex（PFC）contribute to the cognitive process during inhibition and concentration of neurotransmitters is related to response inhibition performance.Due to the difficulty of children neuroimaging study,there are still few research on response inhibition and its development during children’s early school years and,especially,the possible function of neurotransmitters in the development of response inhibition.The focus of this research is to address the individual differences in response inhibition ability among early school-age children and the corresponding neural mechanism.In this study,after a magnetic resonance spectroscopy（MRS）scan,subjects performed a stop-signal task with functional magnetic resonance imaging（f MRI）scanning.Behavior tasks,along with f MRI and MRS scans,which compared to those of young adults,provided clues to children’s individual difference of response inhibition and underlying neural mechanism.The reaction time and stop-signal reaction time of children were significantly longer than those of young adults,while children’s accuracy was significantly poorer.Both children and adults showed proactive response inhibition,and adults exhibited proactive adjustment ability whereas children did not.Activation of children’s inferior frontal gyrus was observed during task,whereas adults’ brain activation was wider and stronger during task.In early school-age children,this research further revealed a negative correlation between Gamma aminobutyric acid（GABA）concentration in dorsal lateral prefrontal cortex（DLPFC）and response inhibition performance,as well as a positive correlation between excitatory/inhibitory ratio and response inhibition performance.However,there was no significance of correlation between GABA（or glutamate）concentration and performance in adults,which may because that the rapid development period（which is marked by changes of neurochemical environment）has passed in young adults.In addition,GABA concentration is positively correlated with DLPFC activation in children.In summary,combining Stop-signal task with f MRI and MRS scans,this study revealed neural mechanism of response inhibition in early school-age children: though inferior to adults,children in early school years performed relatively well in response inhibition tasks;response inhibition develops rapidly with great individual differences,may relate to the neurochemical environment changes.