Browsing by Subject "Motivational control"

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    Cortical and Subcortical correlates of emotional control across adolescent development
    (2013-08) Porter, James Norby
    The neural mechanisms of motivational and emotional processing are of particular interest to the study of adolescent development. Magnetic resonance imaging (MRI) studies show the ventral striatum (especially nucleus accumbens [NAcc]), the amygdala, and the prefrontal cortex (PFC) to be reliable neural correlates of processing stimuli with hedonically valenced content. Current models theorize that the relative levels of maturity of these three regions, from both structural and functional standpoints, strongly influence an individual's tendencies towards impulsive, risky decision-making in the presence of motivationally salient stimuli. This study recruited pre- to early-adolescents, adolescents, and young adults to assess neural correlates of control over emotional reactivity while performing a novel functional MRI (fMRI) task, referred to here as the interval timing task. The task tested individual's abilities to perceive and recreate discrete time intervals, and required deliberate perceptual, cognitive, and motor control in the presence of strongly and weakly valenced visual stimuli. This paper describes the development of the interval timing task and presents comprehensive analyses of alterations due to task parameters as well as inter-individual characteristics of age and sex upon both participants' behavioral performances and their blood-oxygen-level-dependent (BOLD) responses. Additionally, this paper presents an alternative analysis of the fMRI data that can inform the current debate on the extent to which the NAcc displays a specificity for processing positively valenced information or if it is also integral to the processing of negatively valenced information.