Individual differences in impulsive behavior have received growing attention, particularly because impulsive choice is a primary endophenotype that predicts a wide range of problem behaviors. Impulsive choice occurs when choosing between a smaller reward that is available after a shorter delay (SS) and a larger reward after a longer delay (LL). Impulsive individuals tend to choose the SS reward even when the LL is more advantageous. Impulsive choice is a trait in humans, and in rats, and trait impulsive choice has been indicated as a primary endophenotype for attention deficit hyperactivity disorder (ADHD). High levels of impulsive choice are also associated with substance abuse, pathological gambling, and obesity as well as several other diseases and disorders. While impulsive choice is clearly related to a number of human health problems, identifying whether an individual is impulsive is not sufficient. Growing evidence suggests that there are two distinct pathways to impulsivity: one through deficits in time processing and one through deficits in reward processing. In addition to developing assays for identifying the contribution of timing and reward processes to impulsive choice in our previous NIMH award, upon which this renewal is based, we implemented several different time-based neurocognitive interventions that successfully promoted self-control. We found that the interventions operated to improve core timing processes by increasing temporal discrimination abilities. The present proposal therefore seeks to gain a deeper understanding of the two pathways to impulsivity, and to expand on our previously developed time-based interventions to moderate individual differences in impulsive choice.
Aim 1 will determine the durability and generalizability of the time-based neurocognitive interventions, which is important for determining their efficacy for future translational applications.
Aim 2 will isolate the mechanisms of action of the time-based interventions. We propose two separate time-based mechanisms that improve self-control: (1) improving delay tolerance, which leads to an increased ability to wait for longer delays, and (2) increasing temporal discrimination, which promotes the ability to make well-informed choices.
Aim 2 will determine the nature and degree of contribution of these two components to the effectiveness of the time- based interventions.
Aim 3 will employ either time-based or reward-based interventions to override deficits in timing and/or reward processing, providing different pathways to improving self-control. The combined set of studies will significantly advance our understanding of the functioning of the two pathways to impulsivity and will deepen our understanding of the neuro-cognitive interventions to increase their translational potential.
Impulsive choice is a trait variable that is linked with Attention Deficit Hyperactivity Disorder (ADHD), drug use and abuse, gambling, and obesity, as well as a several other diseases and disorders. Targeted neurocognitive time-based interventions have been developed to mitigate impulsive choice in rats by improving time processing or reward processing. The studies will use the neurocognitive interventions to further delineate the nature of deficits in impulsive choice, and to increase the translational efficacy of the interventions.
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