Integration and Segregation of the Brain Relate to Stability of Performance in Children and Adolescents with Varied Levels of Inattention and Impulsivity.

It is common to find that individuals with attention-deficit/hyperactivity disorder (ADHD) produce more variable responses when performing cognitive tasks. The neural mechanism associated with heightened response time variability (RTV) is not well understood in ADHD nor in typically developing individuals. One potential mechanism that might be associated with increased RTV is functional connectivity of the brain, and specifically inefficient connections. This study examined the relationships among functional connectivity of the brain, RTV, and levels of ADHD symptoms, using a cross-sectional developmental design. Twenty children aged 9-12 years and 49 adolescents aged 15-18 years completed the Sustained Attention to Response Task with flanker interference while electroencephalography (EEG) was recorded. The Conners 3 questionnaire was used to measure the participants' levels of ADHD symptoms. Parameters reflecting different aspects of RTV were computed using ex-Gaussian and fast Fourier transform techniques. Functional connectivity between 64 electrodes was computed for the task period, and global efficiency reflecting functional integration and modularity reflecting strength of functional segregation were computed. Greater global efficiency in the theta band was associated with decreased RTV. Increased integration during the task may help to combine information more efficiently and produce stable responses. When congruent flankers were present, children with greater modularity in the beta band showed greater tau, which is thought to reflect attentional lapses. This association was not observed when incongruent flankers were present. Brains with increased strength of segregated activity might be more prone to attentional lapses, especially during simpler tasks.