The project comprised two main work packages (WP1 and WP2), combining behavioural and neuroimaging approaches to investigate how fibromyalgia (FM) affects decision-making processes related to effort, delay, and interoception.
WP1 – Behavioural study
The first part of the project involved a laboratory-based behavioural study comparing individuals with FM to age- and sex-matched controls. Participants engaged in three decision-making tasks in which they could earn real rewards (raffle tickets) by either exerting physical effort (walking on a treadmill), performing a cognitive effort task (short memory task), or waiting for a delayed outcome. Effort levels were individually calibrated to participants’ capacity to ensure comparability across groups. Additional questionnaires and behavioural tasks assessed bodily awareness and interpretation of bodily sensations.
The results revealed a specific alteration in attitudes towards physical effort among individuals with FM. They required higher levels of reward to engage in physically demanding tasks, particularly at higher effort intensities, compared to controls. Importantly, no differences were observed for cognitive effort discounting, suggesting that motivational deficits in FM are not general but domain-specific. Delay discounting results further supported this conclusion: FM participants were more willing to wait for delayed rewards, particularly at lower reward levels, indicating heightened motivation by outcomes rather than reduced overall motivation. Furthermore, the choice to engage in more effortful physical tasks was associated with higher self-reported anxiety, physical fatigue sensations, and alexithymia, highlighting a link between altered bodily awareness and decision-making in FM.
WP2 – Behavioural-fMRI study
The second part of the project employed a combined behavioural and neuroimaging approach. Twenty-five FM participants and 25 matched controls completed two effort discounting tasks inside the MRI scanner (physical effort: continuous button pressing; cognitive effort: memory-based), along with interoception and bodily perception measures.
Behaviourally, results were consistent with WP1: no group differences were found in cognitive effort discounting, and no significant differences emerged for physical effort in the scanner task. The lack of differences in physical effort may be related to the specific design of the scanner task, which required repetitive button-pressing rather than a naturalistic physical effort, such as walking. Together, these findings reinforce the conclusion that FM is not characterised by generalised motivational deficits.
In contrast, pronounced differences emerged in interoception and bodily state perception. While groups did not differ in interoceptive accuracy, confidence, or insight on the heartbeat counting task, FM participants reported greater interoceptive difficulties (Interoception Sensory Questionnaire) and showed reduced differentiation between emotional and non-emotional bodily states in the Body Mapping Task. These results indicate that FM is associated with altered interpretation and integration of bodily signals, which may contribute to pain experience and effort-related decision-making.
At the neural level, effort-based decision-making engaged a network spanning prefrontal regions (medial frontal gyrus, frontal pole, precentral gyrus), supramarginal gyrus, and insula, consistent with prior literature. No group differences were found during cognitive effort discounting, mirroring behavioural findings. However, during physical effort discounting, controls showed greater activation than FM participants in the lateral occipital cortex, a region implicated in uncertainty evaluation during decision-making. This suggests that FM participants may engage different neural mechanisms when assessing the costs and benefits of physically effortful actions.
Main achievements
The project provides novel evidence that motivational alterations in FM are domain-specific rather than general, affecting decisions involving physical effort but not cognitive effort. These changes appear closely linked to altered perception and interpretation of bodily sensations rather than to deficits in interoceptive accuracy. The neuroimaging results identify potential neural mechanisms underlying these differences, highlighting altered recruitment of decision-making circuits in FM. Together, these findings contribute to a more nuanced understanding of how disrupted body–brain communication shapes daily decision-making in chronic pain conditions.
