An investigation of executive functioning abilities using non-invasive near-infrared imaging

Executive functioning abilities, which include sustained attention, goal selection, planning, initiation, self-monitoring, and self-awareness, are critical to successful performance of a variety of cognitive and behavioral tasks. Despite the importance of these abilities, the neurobiological correlates of these tasks have only recently become a major focus of neurological and neuropsychological research. In the past few decades, a large number of functional imaging studies have demonstrated that performance of executive functioning tasks tends to be associated with a number of physiological changes in the prefrontal areas of the brain, thereby supporting earlier, clinically-based hypotheses suggesting that the executive functions are primarily localized in the brain's prefrontal cortical regions.; This study examined the neurobiological processes associated with 15 right-handed subjects' performance on two psychometric measures of executive functioning: the Planning subtest of the Woodcock-Johnson Tests of Cognitive Abilities---Third Edition (WJ-III), and the Wisconsin Card Sorting Test: Computer Version---Fourth Edition (WCST:CV-4). These processes were examined using non-invasive near-infrared (NIR) spectroscopy, a technique permitting in vivo monitoring of changes in blood volume and oxygenation levels through analysis of the properties of emitted and reflected light. The data obtained from the NIR imager and from the standardized tasks were used to examine the relationships among the blood volume and/or oxygenation change data obtained via the NIR imager, differences in hemodynamic response patterns differ across tasks, and relationships among hemodynamic and psychometric data.; Bilateral and diffuse increases in both blood oxygenation and blood volume were observed across subjects and tasks, with the WJ-III Planning task associated with significantly greater hemodynamic responses than the WCST:CV-4. Intrasubject activation patterns tended to remain constant across phases of each psychometric task; however, considerable intersubject differences were found. No significant correlations were found between standard scores and mean changes in blood oxygenation levels for either task, or between standard scores and blood volume changes on the Planning task; however, significant negative correlations were found between WCST standard scores and mean changes in blood volume in three of four prefrontal areas examined. Implications of the study, both for further research and for applied psychological practice, are discussed.