Universität zu Köln

Mathar, David ORCID: 0000-0003-3411-7867, Abdoust, Mani Erfanian, Marrenbach, Tobias, Tuzsus, Deniz and Peters, Jan ORCID: 0000-0002-0195-5357 (2022). The catecholamine precursor Tyrosine reduces autonomic arousal and decreases decision thresholds in reinforcement learning and temporal discounting. PLoS Comput. Biol., 18 (12). SAN FRANCISCO: PUBLIC LIBRARY SCIENCE. ISSN 1553-7358

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Abstract

Supplementation with the catecholamine precursor L-Tyrosine might enhance cognitive performance, but overall findings are mixed. Here, we investigate the effect of a single dose of tyrosine (2g) vs. placebo on two catecholamine-dependent trans-diagnostic traits: model-based control during reinforcement learning (2-step task) and temporal discounting, using a double-blind, placebo-controlled, within-subject design (n = 28 healthy male participants). We leveraged drift diffusion models in a hierarchical Bayesian framework to jointly model participants' choices and response times in both tasks. Furthermore, comprehensive autonomic monitoring (heart rate, heart rate variability, pupillometry, spontaneous eye-blink rate) was performed both pre- and post-supplementation, to explore potential physiological effects of supplementation. Across tasks, tyrosine consistently reduced participants' RTs without deteriorating task-performance. Diffusion modeling linked this effect to attenuated decision-thresholds in both tasks and further revealed increased model-based control (2-step task) and (if anything) attenuated temporal discounting. On the physiological level, participants' pupil dilation was predictive of the individual degree of temporal discounting. Tyrosine supplementation reduced physiological arousal as revealed by increases in pupil dilation variability and reductions in heart rate. Supplementation-related changes in physiological arousal predicted individual changes in temporal discounting. Our findings provide first evidence that tyrosine supplementation might impact psychophysiological parameters, and suggest that modeling approaches based on sequential sampling models can yield novel insights into latent cognitive processes modulated by amino-acid supplementation. Author summary Model-based control during reinforcement learning and temporal discounting have emerged as two candidates delivering on the promise of the Research Domain Criteria as trans-diagnostic characteristics that seem to go awry in a broad range of psychiatric illnesses. Both processes rely on catecholamine transmission and thus may benefit from L-tyrosine supplementation. Here, we tested this in a placebo controlled within-subjects design. On a physiological level, tyrosine intake reduced participants' arousal as revealed by increases in pupil dilation variability and reductions in heart rate compared with placebo. With respect to task performance, we found that following tyrosine intake participants' response times decreased consistently in both tasks without deteriorating task performance. Hierarchical drift diffusion modeling linked this with attenuated decision-thresholds in both tasks. Despite this reduced speed-accuracy trade-off, tyrosine seemed to increase goal-directed control as evident in increased reliance on model-based computations during reinforcement learning and if anything reduced temporal discounting of rewards. Our findings highlight that deeper insights into cognitive effects of supplementation can be gained from applying comprehensive computational models.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mathar, David UNSPECIFIED orcid.org/0000-0003-3411-7867 UNSPECIFIED Abdoust, Mani Erfanian UNSPECIFIED UNSPECIFIED UNSPECIFIED Marrenbach, Tobias UNSPECIFIED UNSPECIFIED UNSPECIFIED Tuzsus, Deniz UNSPECIFIED UNSPECIFIED UNSPECIFIED Peters, Jan UNSPECIFIED orcid.org/0000-0002-0195-5357 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-666680
DOI:	10.1371/journal.pcbi.1010785
Journal or Publication Title:	PLoS Comput. Biol.
Volume:	18
Number:	12
Date:	2022
Publisher:	PUBLIC LIBRARY SCIENCE
Place of Publication:	SAN FRANCISCO
ISSN:	1553-7358
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language EYE BLINK RATE; EMOTIONAL AROUSAL; DOPAMINE NEURONS; WORKING-MEMORY; COGNITIVE PERFORMANCE; INTERTEMPORAL CHOICE; DELAYED REINFORCERS; SUBTHALAMIC NUCLEUS; PARKINSONS-DISEASE; PREDICTION ERRORS Multiple languages Biochemical Research Methods; Mathematical & Computational Biology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/66668