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The impact of traumatic stress on Pavlovian biases

Published online by Cambridge University Press:  23 June 2017

O. T. Ousdal*
Affiliation:
Department of Radiology, Haukeland University Hospital, Bergen, Norway Wellcome Trust Centre for Neuroimaging, University College London, London, UK
Q. J. Huys
Affiliation:
Translational Neuromodeling Unit, Institute of Biomedical Engineering, University of Zürich and Swiss Federal Institute of Technology (ETH) Zürich, Zurich, Switzerland Department of Psychiatry, Psychotherapy and Psychosomatics, Centre for addiction disorders, Hospital of Psychiatry, University of Zürich, Zurich, Switzerland
A. M. Milde
Affiliation:
Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway Regional Centre for Child and Youth Mental Health and Child Welfare, UNI Research Health, Bergen, Norway
A. R. Craven
Affiliation:
Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway NORMENT, Centre of Excellence, University of Oslo, Oslo, Norway
L. Ersland
Affiliation:
Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
T. Endestad
Affiliation:
Institute of Psychology, University of Oslo, Oslo, Norway
A. Melinder
Affiliation:
Institute of Psychology, University of Oslo, Oslo, Norway
K. Hugdahl
Affiliation:
Department of Radiology, Haukeland University Hospital, Bergen, Norway Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway NORMENT, Centre of Excellence, University of Oslo, Oslo, Norway Division of Psychiatry, Haukeland University Hospital, Bergen, Norway KG Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
R. J. Dolan
Affiliation:
Wellcome Trust Centre for Neuroimaging, University College London, London, UK Max Planck-University College London Centre for Computational Psychiatry and Ageing, London, UK
*
*Address for correspondence: Olga Therese Ousdal, M.D. Ph.D., Department of Radiology, Haukeland University Hospital, Jonas Lies vei 65, 5021 Bergen, Norway. (Email: olgatherese.ousdal@gmail.com, o.ousdal@ucl.ac.uk)

Abstract

Background

Disturbances in Pavlovian valuation systems are reported to follow traumatic stress exposure. However, motivated decisions are also guided by instrumental mechanisms, but to date the effect of traumatic stress on these instrumental systems remain poorly investigated. Here, we examine whether a single episode of severe traumatic stress influences flexible instrumental decisions through an impact on a Pavlovian system.

Methods

Twenty-six survivors of the 2011 Norwegian terror attack and 30 matched control subjects performed an instrumental learning task in which Pavlovian and instrumental associations promoted congruent or conflicting responses. We used reinforcement learning models to infer how traumatic stress affected learning and decision-making. Based on the importance of dorsal anterior cingulate cortex (dACC) for cognitive control, we also investigated if individual concentrations of Glx (=glutamate + glutamine) in dACC predicted the Pavlovian bias of choice.

Results

Survivors of traumatic stress expressed a greater Pavlovian interference with instrumental action selection and had significantly lower levels of Glx in the dACC. Across subjects, the degree of Pavlovian interference was negatively associated with dACC Glx concentrations.

Conclusions

Experiencing traumatic stress appears to render instrumental decisions less flexible by increasing the susceptibility to Pavlovian influences. An observed association between prefrontal glutamatergic levels and this Pavlovian bias provides novel insight into the neurochemical basis of decision-making, and suggests a mechanism by which traumatic stress can impair flexible instrumental behaviours.

Information

Type
Original Articles
Copyright
Copyright © Cambridge University Press 2017 

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