Neuropsychological perspective on discounting of delayed rewards

The paper presents a review of literature on relationships between activity in the nervous system and temporal discounting. Temporal discounting is defined as a process of a decreasing of the subjective value of a reward, when delay to the reward delivery increases. Steep temporal discounting is related to high impulsivity. Clinical and experimental research with human subjects is presented. Subjects with central nerves system (CNS) injury, described as impulsive, most often have an extensive part of their brain damaged, especially in the area of the frontal lobes. The steep discounting shown by these patients is especially related to the ventromedial prefrontal cortex. Functional magnetic resonance imaging (fMRI) studies on healthy subjects point to a larger number of brain areas involved in decision making related to discounting: the orbitofrontal cortex, cingulate cortex, medial and dorsolateral parts of the frontal lobe, striatum and parietal lobe. Research results indicate the need for further studies, especially including neurological patients with different focal brain injuries in both right and left hemispheres. Increased knowledge on the behaviour of these patients when facing delayed rewards may be of great importance in planning their neurological rehabilitation, among other things.