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Abstract

Rationale: Although methylphenidate and other stimulants have been demonstrated to improvetask performance across a variety of domains, a computationally rigorous account of how these drugsalter cognitive processing remains elusive. Recent applications of mathematical models of cognitiveprocessing and electrophysiological methods to this question have suggested that stimulants improve theintegrity of evidence accumulation processes for relevant choices, potentially through catecholaminergicmodulation of neural signal-to-noise ratios. However, this nascent line of work has thus far been limitedto simple perceptual tasks and has largely omitted more complex “conflict” paradigms that containexperimental manipulations of specific top-down interference resolution processes. Objectives and Methods: To address this gap, this study applied the Conflict Linear Ballistic Accumulator (LBA), a newly proposed model designed for conflict tasks, to data from healthy adults who performed the Multi-Source Interference Task (MSIT) after acute methylphenidate or placebo challenge. Results: Model-based analyses revealed that methylphenidate improved performance by reducing individuals’ response thresholds and by enhancing evidence accumulation processes across all task conditions, either by improving the quality of evidence or by reducing variability in accumulation processes. In contrast, the drug did not reduce bottom-up interference or selectively facilitate top-down interference resolution processes probed by the experimental conflict manipulation. Conclusions: Enhancement of evidence accumulation is a biologically plausible and task-general mechanism of stimulant effects on cognition. Moreover, the assumption that methylphenidate’s effects on behavior are only visible with complex “executive” tasks may be misguided.

Item Type:	Article
Authors/Creators:	Weigard, A and Heathcote, A and Sripada, CS
Keywords:	methylphenidate, stimulants, evidence accumulation, conflict tasks, executive functions, cognitive modeling, computational psychiatry, Bayesian
Journal or Publication Title:	Psychopharmacology
Publisher:	Springer-Verlag
ISSN:	0033-3158
DOI / ID Number:	https://doi.org/10.1007/s00213-019-05316-x
Copyright Information:	Copyright 2019 Springer-Verlag GmbH Germany, part of Springer Nature
Related URLs:	Google Scholar: Heathcote, A UTAS Profile: Heathcote, A
Item Statistics:	View statistics for this item

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