Date of Award

Winter 5-7-2012

Thesis Access

Open Access Honors Thesis

Degree Name

B.S.

Department

Nutrition and Food Science

Faculty Advisor

Dr. Vaibhav Diwadkar

Abstract

Attention Deficit / Hyperactivity Disorder is a neurodevelopmental disorder common among children and adolescent populations whose symptoms are believed to be caused by deficits in executive functioning processes such as working memory. Using fMRI analyses, differences in the modulatory influence exhibited by the dorsal anterior cingulate cortex (dACC) on cortico-striatal regions implicated in working memory (2-back) (Owen et al 2005) was assessed between children with ADHD (twenty-three participants; mean age 6 yrs: 6.4-14.9 yrs) and healthy controls (twenty-six participants; mean age 10.1yrs: 6.3-14.1 yrs). Modulatory influence is defined as the degree to which one region exerts control on another region and was investigated using the analysis tool Psychophysiological Interactions (PPI) (Friston et al. 1997). Results of second level analyses show an increased level of dACC modulation on target regions (parietal lobe, middle frontal gyrus, dorsal pre frontal cortex) in children with ADHD and suggest an underlying inefficiency in control network circuitry. Further investigation into network efficiency was conducted using performance (d’) and latency response data. Statistical analyses of performance and latency response times show similar averages between groups and indicate children with ADHD were not compromised in their ability to complete the 2-Back task. This suggests the differential pattern of dACC modulation observed in children with ADHD is not driven by behavioral symptoms of the psychiatric disorder and allude to functional differences in network circuitry driving the apparent inefficiency. Our inefficiency hypothesis is consistent with other fMRI studies investigating working memory in subjects with ADHD. Future analyses using longitudinal studies of subjects may highlight potential developmental implications on the modulatory behavior of the dACC in children with ADHD.

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