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Updated: May 5, 2026

Pavlovian Conditioned Approach Training in Rats
Published on: February 4, 2016
Serotonin and aversive Pavlovian control of instrumental behavior in humans
Dirk E M Geurts1, Quentin J M Huys, Hanneke E M den Ouden
1Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition and Behavior, Centre for Cognitive Neuroimaging and Department of Psychiatry, 6500 HB, Nijmegen, The Netherlands, Gatsby Computational Neuroscience Unit and Wellcome Trust Centre for Neuroimaging, UCL, WC1N 3AR, London, United Kingdom, Translational Neuromodeling Unit, ETH, University of Zurich, CH-8032 Zurich, Switzerland, and Psychiatry, Psychotherapy and Psychosomatics, University Hospital of Psychiatry Zurich, CH-8032 Zurich, Switzerland.
Abstract:
Adaptive decision-making involves interaction between systems regulating Pavlovian and instrumental control of behavior. Here we investigate in humans the role of serotonin in such Pavlovian-instrumental transfer in both the aversive and the appetitive domain using acute tryptophan depletion, known to lower central serotonin levels. Acute tryptophan depletion attenuated the inhibiting effect of aversive Pavlovian cues on instrumental behavior, while leaving unaltered the activating effect of appetitive Pavlovian cues. These data suggest that serotonin is selectively involved in Pavlovian inhibition due to aversive expectations and have implications for our understanding of the mechanisms underlying a range of affective, impulsive, and aggressive neuropsychiatric disorders.
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