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Current Drug Targets
ISSN (Print): 1389-4501
ISSN (Online): 1873-5592
VOLUME: 2
ISSUE: 4
DOI: 10.2174/1389450013348155      Price:  $58









Working Memory in ADHD: Prefrontal/Parietal Connections

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Author(s): F Levy and M Farrow
Pages 347-352 (6)
Abstract:
Current theories of dopaminergic and noradrenergic mechanisms, which are thought to be of importance in the regulation of attention are reviewed. A biphasic model of dopaminergic function is described, in which tonic dopamine exerts a suppressive influence on subcortical dopamine systems by altering tonic/phasic dopaminergic relationships. Noradrenergic mechanisms are of importance in modulating sensory processing at the prefrontal cortical level. The work of Silberstein and colleagues utilizing Steady-State Visually Evoked Potential, during the course of an A-X Continuous Performance Task enables examination of the spatial distribution and dynamics of electrical brain activity during the task. The maintenance of activation in the interval between A and X provides a measure of working memory, thought to be related to prefrontal-parietal activation, which is facilitated by administration of methylphenidate to children with ADHD, suggesting that working memory may be a core deficiency in children with ADHD. While tonic dopamine activity in vental striatum/accumbens gates inhibitory activity, dorsolateral prefrontal-parietal connections allow maintenance of working memory required for goal completion.
Affiliation:
correspondence to this author at the Avoca Clinic, Prince of Wales Hospital, Sydney, NSW 2031, Australia