Dissecting impulsivity: Brain mechanisms and neuropsychiatric implications

Abstract

The construct of impulsivity is considered within a neuropsychological and neuroscientific theoretical framework that considers possible subdivisions based on discounting of reward, premature responding, and motor inhibition in experimental animals and humans. One neural system including the medial prefrontal cortex and nucleus accumbens mediates ‘waiting’ impulsivity, including premature responding in the rodent 5-choice serial reaction time task, with dopaminergic, serotoninergic, and noradrenergic modulatory influences. A second system including the dorsal striatum and associated circuitry including the inferior frontal cortex mediates inhibitory control and is modulated by dopaminergic and noradrenergic systems. Translational applications of these findings are identified with respect to human substance use disorders and attention-deficit/hyperactivity disorder. Theoretical implications for concepts of cognitive control are also considered, including ‘reflection impulsivity’ and the notion of pre-commitment that enables resistance to temptations, possibly involving hierarchical mechanisms of decision-making cognition.