Neural Systems Underlying Individual Differences in Intertemporal Decision-making

Abstract

Excessively choosing immediate over larger future rewards, or delay discounting (DD), associates with multiple clinical conditions. Individual differences in DD likely depend on variations in the activation of and functional interactions between networks, representing possible endophenotypes for associated disorders, including alcohol use disorders (AUDs). Numerous fMRI studies have probed the neural bases of DD, but investigations of large-scale networks remains scant. We addressed this gap by testing whether activation within large-scale networks during “Now/Later” decision-making predicts individual differences in DD. To do so, we scanned 95 social drinkers (18–40 years; 50 females) using fMRI during hypothetical choices between small monetary amounts available “today” or larger amounts available later. We identified neural networks engaged during Now/Later choice using independent component analysis (ICA) and tested the relationship between component activation and degree of DD. The activity of two components during Now/Later choice correlated with individual DD rates: a temporal lobe network positively correlated with DD, while a frontoparietal-striatal network negatively correlated with DD. Activation differences between these networks predicted individual differences in DD and their negative correlation during Now/Later choice suggests functional competition. A generalized psychophysiological interactions (gPPI) analysis confirmed a decrease in their functional connectivity during decision-making. The functional connectivity of these two networks negatively correlates with alcohol-related harm, potentially implicating these networks in AUDs. These findings provide novel insight into the neural underpinnings of individual differences in impulsive decision making with potential implications for addiction and related disorders in which impulsivity is a defining feature.

COMT Val158Met Polymorphism Exerts Sex-Dependent Effects on fMRI Measures of Brain Function

“…While in the MRI scanner, participants performed a delay discounting task optimized for fMRI studies. The details of this task, in which participants selected between sets of smaller, immediate hypothetical monetary rewards (“ Now ”), or larger, delayed rewards (“ Later ”), have been reported previously (Boettiger et al, 2007 , 2009 ; Altamirano et al, 2011 ; Smith and Boettiger, 2012 ; Kelm and Boettiger, 2013 ; Smith et al, 2014a , 2015 ; Elton et al, 2017 ) and are further detailed in the Supplementary Materials. Subjects underwent six consecutive functional MRI scans (~8 min per scan) each of which included 32 Now -vs.- Later decisions, consisting of four decision trial types presented psuedorandomly: “WANT,” “DON'T WANT,” “SOONER,” or “LARGER.”…”

Alterations in functional brain networks associated with loss-chasing in gambling disorder and cocaine-use disorder

“…ICA has been proposed to have several advantages over GLM, including less susceptibility to functional heterogeneity and the ability to separate inhibitory and excitatory influences on neuronal activity (Xu et al, 2015; Xu et al, 2016). ICA is a data-driven, network-based computational procedure that has been used to identify functional alterations in the multiple brain networks that contribute to cognitive control (Worhunsky et al, 2013), decision-making (Elton et al, 2017), and during resting-state (Ding and Lee, 2013) in individuals with substance-use disorders. Thus, the current study aimed to extend previous investigations of loss-chasing behavior by examining activity in functional brain networks in individuals with gambling disorder (GD), individuals with cocaine-use disorder (CUD) and a healthy comparison (HC) sample.…”

Neural correlates of delay of gratification choice in young children: Near‐infrared spectroscopy studies

“…Casey et al (2011) reported that children who delayed their gratification (high delayers) showed stronger activation in the inferior frontal gyrus during a response inhibition task in adulthood than did those who did not delay their gratification (low delayers). Moreover, adult brain imaging studies repeatedly show that high delayers show stronger lateral prefrontal activations than low delayers do (Ballard & Knutson, 2009;Elton, Smith, Parrish, & Boettiger, 2017). However, it is still unknown whether behavioral performance is related to activations in the prefrontal regions in young children.…”