Dopamine Promotes Cognitive Effort by Biasing the Benefits Versus Costs of Cognitive Work

Abstract

Stimulants like methylphenidate are increasingly used for cognitive enhancement, but precise mechanisms are unknown. Here we show that methylphenidate boosts willingness to expend cognitive effort by altering the benefit-to-cost ratio of cognitive work. Willingness to 15 expend effort was greater for participants with higher striatal dopamine synthesis capacity, while methylphenidate and sulpiride -a selective D2 receptor agent -increased cognitive motivation more for participants with lower synthesis capacity. A sequential sampling model informed by momentary gaze revealed that decisions to expend effort are related to amplification of benefitversus-cost information attended early in the decision process, while the effect of benefits is 20 strengthened with higher synthesis capacity and by methylphenidate. These findings demonstrate that methylphenidate boosts the perceived benefits-versus-costs of cognitive effort by modulating striatal dopamine signaling. Main Text:Cognitive control is subjectively effortful, causing people to avoid demanding tasks (1) 25 and to discount goals (2, 3), but incentives can offset these costs (2). Striatal dopamine invigorates physical action by mediating the tradeoff between physical costs and benefits (4). In cortico-striatal loops governing action selection, dopamine has opponent effects on D1 and D2expressing medium spiny neurons, which are thought to modulate the relative sensitivity to the benefits versus the costs of actions (5). Given that similar mechanisms are thought to govern 30 cognitive action selection (6-8), we hypothesized that striatal dopamine could promote willingness to exert cognitive effort, boosting motivated cognitive control for attention, planning, and decision-making (9-12).Converging evidence from research on Parkinson's disease (13)(14)(15)(16)(17), showing dopaminedependent changes in cognitive motivation, provides an initial basis for this conjecture. 35 Moreover, catecholamine-enhancing psychostimulants alter cognitive effort-based choice in both rodents (10) and humans (18). This raises the question of whether commonly used "smart drugs" act by enhancing the willingness rather than ability to exert cognitive control. Indeed, the dominant interpretation of stimulant effects is that they improve cognitive processing, via direct effects on cortical areas,

Considering what we know and what we don't know: Expectations and confidence guide value integration in value-based decision-making

“…It incorrectly predicts slower response times for higher set confidence and no effect of relative confidence. that, unlike several past studies (Cavanagh et al, 2014;Krajbich et al, 2010;Westbrook et al, 2020), we did not find that attention exerted an independent (additive) influence on the likelihood of choosing one option or another, over and above its role in enhancing the influence of value on choice.…”

“…The aDDM extends sequential sampling models, in which evidence in favor of potential options is sampled repeatedly and accumulated over time (usually until some threshold is reached; Ratcliff et al, 2016;Bogacz et al, 2006;Usher & McClelland, 2001;Wang, 2012), with a parameter that discounts value information from unattended items. According to this model, choice biases arise from a multiplicative effect of value and attention on choice, such that in the appetitive domain, increased attention to an option increases the likelihood that it will be chosen, whereas in the aversive domain increased attention to an option decreases the likelihood that it will be chosen (Armel et al, 2008;Smith & Krajbich, 2019, but see Cavanagh et al, 2014;Westbrook et al, 2020;Kaanders et al, 2022).…”

Nucleus accumbens D1-receptors regulate and focus transitions to reward-seeking action

“…The prospect of reward can positively shape both the speed and precision of behaviour (Guitart-Masip, Duzel, Dolan, & Dayan, 2014;Kawagoe, 1998;Manohar et al, 2015;Shadmehr, Reppert, Summerside, Yoon, & Ahmed, 2019), and several lines of evidence suggest that dopamine may play a key role in mediating aspects of both processes (Beierholm et al, 2013;Hamid et al, 2015;Manohar et al, 2015;Niv et al, 2007;Westbrook et al, 2020). As expected, rats' performance in the current experiment was also strongly affected by the reward size on offer.…”

Chemistry of the Adaptive Mind: Lessons from Dopamine

“…To provide direct evidence for a key role of striatal dopamine in cognitive work, we recently employed an adapted version of the cognitive effort discounting paradigm in a large multisession pharmacological PET study with 50 healthy students to demonstrate that methylphenidate, the selective dopamine D2 receptor agent sulpiride, and individual variation in striatal dopamine synthesis capacity all increase willingness to expend cognitive effort for reward (Westbrook et al, 2019). All participants underwent a dopamine PET scan with the radiotracer [ 18 F]DOPA, the uptake of which indexes the degree to which dopamine is synthesized in the striatal terminals of midbrain dopamine neurons.…”