Neurochemical modulation of orbitofrontal cortex function

Abstract:

This chapter reviews evidence indicating a close association of the orbitofrontal cortex (OFC) with ascending modulatory neurotransmitter systems. It focuses on the neurochemical modulation of performance in such paradigms as reversal learning and risk taking (Cambridge Gamble Task), which have been linked to orbitofrontal functioning based on neuropsychological and neuroimaging analyses. These paradigms have been studied following pharmacological and neurotoxic manipulations of the serotoninergic, dopaminergic, noradrenergic, and cholinergic systems. Manipulations of the serotoninergic system modulate reversal learning and impulsive responding in rodents. In humans, tryptophan depletion has been associated with reversal learning deficits as well as alterations in risky decision-making. Data for orbitofrontal-specific effects of manipulations of the dopaminergic, noradrenergic, and cholinergic modulatory systems are much more limited, although disruption of cholinergic projections in rodents do produce behavioral deficits that are reminiscent of those seen following orbitofrontal lesions.