Lipopolysaccharide Alters Motivated Behavior in a Monetary Reward Task: a Randomized Trial.
Inflammation-induced sickness is associated with a large set of behavioral alterations; however, its motivational aspects remain poorly explored in humans. The present study assessed the effect of lipopolysaccharide (LPS) administration at a dose of 2 ng/kg of body weight on motivation in 21 healthy human subjects in a double-blinded, placebo (saline)-controlled, cross-over design. Incentive motivation and reward sensitivity were measured using the Effort Expenditure for Rewards Task (EEfRT), in which motivation for high-effort/high-reward trials vs low-effort/low-reward trials are manipulated by variations in reward magnitude and probability to win. Because of the strong interactions between sleepiness and motivation, the role of sleepiness was also determined. As expected, the probability to win predicted the choice to engage in high-effort/high-reward trials; however, this occurred at a greater extent after LPS than after saline administration. This effect was related to the level of sleepiness. Sleepiness increased motivation to choose the high-effort/high-reward mode of response, but only when the probability to win was the highest. LPS had no effect on reward sensitivity either directly or via sleepiness. These results indicate that systemic inflammation induced by LPS administration causes motivational changes in young healthy subjects, which are associated with sleepiness. Thus, despite its association with energy-saving behaviors, sickness allows increased incentive motivation when the effort is deemed worthwhile.
Division for Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.|Stress Research Institute, Stockholm University, Stockholm, Sweden.|Institute of Medical Psychology and Behavioral Immunobiology, Universitätsklinikum Essen, Essen, Germany.
Julie
http://orcid.org/0000-0001-8323-0714
J
Lasselin
Department of Psychology, Emory University, Atlanta, GA, USA.
Michael T
MT
Treadway
Division of Internal Medicine, Department of Symptom Research, The University of Texas, MD Anderson Cancer Center, Houston, TX, USA.
Tamara E
TE
Lacourt
Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden.
Anne
A
Soop
Division for Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Mats J
MJ
Olsson
Division for Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.|Stress Research Institute, Stockholm University, Stockholm, Sweden.
Bianka
B
Karshikoff
Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden.
Sofie
S
Paues-Göranson
Division for Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.|Stress Research Institute, Stockholm University, Stockholm, Sweden.|Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm, Sweden.
John
J
Axelsson
Division of Internal Medicine, Department of Symptom Research, The University of Texas, MD Anderson Cancer Center, Houston, TX, USA.
Robert
R
Dantzer
Division for Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.|Stress Research Institute, Stockholm University, Stockholm, Sweden.|Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm, Sweden.
Mats
M
Lekander
D000328:Adult; D002755:Choice Behavior / Q000187:drug effects*; D005260:Female; D006801:Humans; D055809:Illness Behavior / Q000502:physiology*; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009042:Motivation / Q000187:drug effects*; D011597:Psychomotor Performance / Q000187:drug effects*; D012201:Reward; D014851:Wakefulness / Q000187:drug effects*; D055815:Young Adult
D008070:Lipopolysaccharides