Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Neuroscience

Supervisor

Stojanoski, Bobby

Affiliation

Ontario Tech University, The University of Western Ontario

2nd Supervisor

Mohsenzadeh, Yalda

Co-Supervisor

Abstract

Childhood and adolescence are marked by improvements to cognition and by the emergence of neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD). What neural mechanisms are associated with cognitive development in ADHD? In this study, I applied machine learning models to functional connectivity profiles to identify patterns of network connectivity that predict various cognitive abilities in a group of participants ages 6 to 16 with ADHD. The models successfully predicted IQ, visual spatial, verbal comprehension, and fluid reasoning in children ages 6 to 11, but not adolescents. Furthermore, the models identified connections with the default mode, memory retrieval, and dorsal attention networks as driving prediction during early and middle childhood, but connections with the somatomotor, cingulo-opercular and frontoparietal networks were more important in middle childhood. These results suggest that computational models can identify neural mechanisms associated with predicting cognitive abilities in children and adolescents with ADHD using naturalistic stimuli.

Summary for Lay Audience

One of the most common disorders in children that affects the development of the brain is attention deficit hyperactivity disorder (ADHD). ADHD is defined by abnormal amounts of inattention, impulsivity, and hyperactivity—such as when a student has trouble paying attention to the teacher’s school lesson. From previous scientific studies, it is believed that ADHD is linked to problems with controlling a person’s behavior including suppressing inappropriate or unwanted actions, switching between different mental processes, and remembering information for a short period of time. However, it is not clear how these mental or cognitive abilities relate to children’s brains with ADHD and how they change as children become adolescents. Specifically, how does the brain activity in children and adolescents diagnosed with ADHD relate to cognitive abilities such as IQ and working memory? In this study, I explored this question by using computer models to find links between brain activity—while participants watched the movie “Despicable Me”—to various cognitive abilities in children and adolescents ages 6 to 16 with ADHD. I found that the models could predict IQ, visual spatial ability, and verbal comprehension ability in early childhood. In addition to these three cognitive abilities, the models could also predict fluid reasoning and working memory ability in middle childhood. This suggests that the models can capture different cognitive abilities in children of different ages. But how do the models predict cognition from brain activity? By analyzing the models, they pointed to a set of brain networks that were more important than other networks to predict cognitive ability. These networks are believed to participate in memory, attention, and motor control, and this set of important networks changed as the models were trained on children in different developmental stages. Overall, these findings provide evidence that computer models can predict cognitive ability in children with ADHD and they contribute to our understanding of how brain activity is linked to different cognitive abilities in children with ADHD.

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