Analysis of Assessment and Hemodynamic Activation in the Prefrontal Cortex: An Investigation of Executive Function
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Executive function (EF) refers to the group of cognitive processes that guide human behavior. EF dysfunction is characteristic of a number of clinical conditions such as ADHD. Functional Near-Infrared Spectroscopy (fNIRS) is an economical and less invasive means to image the cortex during tasks of EF to visualize cognitive processes. Measuring hemodynamics in those with and without ADHD during EF tasks, and comparing hemodynamics, EF performance and ratings of EF in daily functioning can yield additional insight into the functional relationship of the cortex and behavior. This study utilized the EXecutive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER), Trail Making Test (TMT), Twenty Questions (20Q) task from the Delis-Kaplan Executive Function System (DKEFS), and the Behavior Rating Inventory of Executive Function-Adult (BRIEF-A) Behavior Regulation Index (BRI) and Metacognition Index (MCI). NIRS data was collected during the EF performance tasks and results were calculated based on average hemodynamic responses. Additional questions were addressed regarding the association of EF ratings to EF performance, whether there was an association between digital and non-digital EF tasks, and whether performance differed between those with and without ADHD in terms of hemodynamics and performance or only performance variables. A moderate association was found between BRI and decreased oxygenated hemoglobin (oxyHb) in the left DLPFC during Set Shifting. Higher MCI was moderately associated with decreased oxyHb in the left DLPFC during a task of inhibition and sustained attention, and improved performance on N-Back was moderately associated with increased oxyHb in bilateral DLPFC during Set Shifting. No statistically significant differences were found between ADHD and Non-ADHD groups in PFC hemodynamics during EF tasks; however, ADHD participants exhibited greater impairment on ratings of EF. No statistically significant associations between digital and non-digital tasks were found. Findings confirm deficits in everyday EF in those with ADHD; however, continued use of digital tasks to assess EF constructs, and use of those results for diagnostic purposes is not consistently supported in the literature. Additional information regarding use of EF tasks in those with and without ADHD may provide additional insight into the connection between neurophysiology and everyday function.
Vidrine, Stephanie Michelle (2017). Analysis of Assessment and Hemodynamic Activation in the Prefrontal Cortex: An Investigation of Executive Function. Doctoral dissertation, Texas A & M University. Available electronically from