Changes in Neural Connectivity Underlie Decision Threshold Modulation for Reward Maximization

Abstract

Using neuroimaging in combination with computational modeling, this study shows that decision threshold modulation for reward maximization is accompanied by a change in effective connectivity within corticostriatal and cerebellar-striatal brain systems. Research on perceptual decision making suggests that people make decisions by accumulating sensory evidence until a decision threshold is crossed. This threshold can be adjusted to changing circumstances, to maximize rewards. Decision making thus requires effectively managing the amount of accumulated evidence versus the amount of available time. Importantly, the neural substrate of this decision threshold modulation is unknown. Participants performed a perceptual decision-making task in blocks with identical duration but different reward schedules. Behavioral and modeling results indicate that human subjects modulated their decision threshold to maximize net reward. Neuroimaging results indicate that decision threshold modulation was achieved by adjusting effective connectivity within corticostriatal and cerebellar-striatal brain systems, the former being responsible for processing of accumulated sensory evidence and the latter being responsible for automatic, subsecond temporal processing. Participants who adjusted their threshold to a greater extent (and gained more net reward) also showed a greater modulation of effective connectivity. These results reveal a neural mechanism that underlies decision makers' abilities to adjust to changing circumstances to maximize reward.

Value Is in the Eye of the Beholder: Early Visual Cortex Codes Monetary Value of Objects during a Diverted Attention Task

“…This finding is not surprising since it has been reported that regions of frontal cortex, including dorsal and medial PFC, play a crucial role in the active biasing of task-relevant processes against strong competing alternatives (Chadick et al, 2014; Chadick and Gazzaley, 2011; Miller and Cohen, 2001). Furthermore, evidence from several species suggests that the striatum contributes directly to decision-making, action selection and initiation (Green et al, 2012; Balleine et al, 2007). This finding suggests that the process of tracking values occurs early in perception, and that more frontal brain regions, involved in executive functions, are not recruited in value representation unless a choice between items is necessary.…”

A statistical test for the optimality of deliberative time allocation

“…It has been found to closely match configurations of choice and response times in a variety of tasks ranging from perceptual discrimination (Ratcliff & Rouder, 2000, 2002Smith, Ratcliff, & Wolfgang, 2004) to recognition memory (Ratcliff, 1978;Starns & Ratcliff, 2014), and more recently, value-based judgment (Krajbich, Armel, & Rangel, 2010;Milosavljevic, Malmaud, Huth, Koch, & Rangel, 2010;Krajbich & Rangel, 2011;Krajbich et al, 2012Krajbich et al, , 2015. Moreover, direct measurements of neural activity reveal the implementation of evidence accumulation processes that fit the model's structure (Hanes & Schall, 1996;Shadlen & Newsome, 2001;Gold & Shadlen, 2002;Ratcliff, Cherian, & Segraves, 2003;Gluth, Rieskamp, & Büchel, 2012;Green, Biele, & Heekeren, 2012).…”

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Characterizing the role of the pre‐SMA in the control of speed/accuracy trade‐off with directed functional connectivity mapping and multiple solution reduction

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