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Updated: Apr 18, 2026

Operant Procedures for Assessing Behavioral Flexibility in Rats
Published on: February 15, 2015
Tyrosine promotes cognitive flexibility: evidence from proactive vs. reactive control during task switching
Laura Steenbergen1, Roberta Sellaro1, Bernhard Hommel1
1Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands.
Abstract:
Tyrosine (TYR), an amino acid found in various foods, has been shown to increase dopamine (DA) levels in the brain. Recent studies have provided evidence that TYR supplementation can improve facets of cognitive control in situations with high cognitive demands. Here we investigated whether TYR promotes cognitive flexibility, a cognitive-control function that is assumed to be modulated by DA. We tested the effect of TYR on proactive vs. reactive control during task switching performance, which provides a relatively well-established diagnostic of cognitive flexibility. In a double-blind, randomized, placebo-controlled design, 22 healthy adults performed in a task-switching paradigm. Compared to a neutral placebo, TYR promoted cognitive flexibility (i.e. reduced switching costs). This finding supports the idea that TYR can facilitate cognitive flexibility by repleting cognitive resources.
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