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.

Public Health Relevance

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.

National Institute of Health (NIH)
National Institute of Mental Health (NIMH)
Research Project (R01)
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Biobehavioral Regulation, Learning and Ethology Study Section (BRLE)
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Rossi, Andrew
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Kansas State University
Schools of Arts and Sciences
United States
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Kirkpatrick, Kimberly; Marshall, Andrew T; Steele, Catherine C et al. (2018) Resurrecting the individual in behavioral analysis: Using mixed effects models to address nonsystematic discounting data. Behav Anal (Wash D C) 18:219-238
Bailey, Carrie; Peterson, Jennifer R; Schnegelsiepen, Aaron et al. (2018) Durability and generalizability of time-based intervention effects on impulsive choice in rats. Behav Processes 152:54-62
Stuebing, Sarah L; Marshall, Andrew T; Triplett, Ashton et al. (2018) Females in the forefront: time-based intervention effects on impulsive choice and interval timing in female rats. Anim Cogn 21:759-772
Steele, Catherine C; Peterson, Jennifer R; Marshall, Andrew T et al. (2018) Nucleus accumbens core lesions induce sub-optimal choice and reduce sensitivity to magnitude and delay in impulsive choice tasks. Behav Brain Res 339:28-38
Marshall, Andrew T; Kirkpatrick, Kimberly (2017) Reinforcement learning models of risky choice and the promotion of risk-taking by losses disguised as wins in rats. J Exp Psychol Anim Learn Cogn 43:262-279
Wang, Maya Zhe; Marshall, Andrew T; Kirkpatrick, Kimberly (2017) Differential effects of social and novelty enrichment on individual differences in impulsivity and behavioral flexibility. Behav Brain Res 327:54-64
Marshall, Andrew T; Kirkpatrick, Kimberly (2017) Accumbens D2: Raters of the Loss Outcome. Learn Behav 45:3-4
Steele, Catherine C; Pirkle, Jesseca R A; Kirkpatrick, Kimberly (2017) Diet-induced impulsivity: Effects of a high-fat and a high-sugar diet on impulsive choice in rats. PLoS One 12:e0180510
Smith, Aaron P; Peterson, Jennifer R; Kirkpatrick, Kimberly (2016) Reward Contrast Effects on Impulsive Choice and Timing in Rats. Timing Time Percept 4:147-166
Peterson, Jennifer R; Kirkpatrick, Kimberly (2016) The effects of a time-based intervention on experienced middle-aged rats. Behav Processes 133:44-51

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