Biology subjects

Bergevin, M.

Publications and source records attributed to Bergevin, M..

4 recordsLinked to original sources

bioRxiv2026

Increased perceived effort during contralateral thermal heat pain is not explained by increased intracortical and corticospinal inhibition.

BackgroundPain influences motor function and has been proposed to reduce corticospinal and intracortical excitability. At the same time, performance can be maintained during pain, at the cost of increased perceived effort, a centrally generated signal reflecting resource engagement. Here, we tested whether contralateral thermal heat pain-related changes in corticospinal and intracortical excitability contribute to increased effort perception. MethodsIn this preregistered transcranial magnetic stimulation (TMS) study, twenty-one healthy participants received single and paired pulse TMS at rest and during submaximal isometric right wrist flexions performed at 20% maximal peak force. Trials were conducted under a control condition or during contralateral thermal stimulation (painful or non-painful warm) applied to the left forearm. After each contraction, participants rated the intensity of their perceived effort. Corticospinal and intracortical excitability of the right wrist flexor was assessed at rest and during submaximal contractions. ResultsContralateral heat pain significantly increased perceived effort compared with the control and warm conditions. Contralateral heat pain did not reduce corticospinal or intracortical excitability. Conversely, contralateral heat pain increased corticospinal excitability, reflected primarily in decreased cortical silent period duration. Perceived effort was associated with the subjective experience of pain rather than with TMS-derived variables. ConclusionsThese findings suggest that increased effort during contralateral heat pain cannot be attributed to inhibition of the primary motor cortex or the corticospinal pathway. The higher perceived effort in the presence of contralateral heat pain likely reflects the cognitive cost of pain rather than alterations in the transmission of the motor command.

neuroscience↗

bioRxiv2026

Facing pain is effortful: key role of the supplementary motor area and anterior midcingulate cortex

Pain captures attention and interferes with executive and motor processes. In the presence of pain, increasing effort may represent a compensatory mechanism to counteract pain-related disruption and maintain task performance. In this preregistered fMRI study, we investigated neural mechanisms underlying preserved task performance during pain and increased perceived effort. Forty right-handed participants performed a visuomotor force-matching task consisting of isometric handgrip contractions at a low and high force levels under individually calibrated painful or non-painful thermal stimulation. Thermal stimulation was applied to the left forearm, and participants rated the intensity of perceived effort after each isometric contraction. Maintaining task performance under pain was associated with increased perceived effort and recruited brain regions involved in pain modulation and cognitive control. Region-of-interest analysis showed perceived effort was consistently linked to decreased anterior midcingulate cortex activity, whereas supplementary motor area contributions varied depending on its role in motor execution or pain processing. Across experimental condition, motor, pain-modulatory and cognitive-control regions were associated with effort perception. Independently of condition, effort perception was modulated by ventromedial prefrontal cortex and ventral striatum. These findings indicate that effort perception is a complex phenomenon reflecting brain activity within areas involved in motor, executive and valuation processes. Significance StatementThis study advances our understanding of the neural mechanisms underlying task performance under pain and increased effort perception. Brain activity was measured during a visuomotor force-matching task performed in the presence or absence of pain. By contrasting task-related activity between painful and non-painful conditions, we identified regions associated with cognitive control and pain modulation involved in preserving task performance under pain. By correlating activity in regions of interest with ratings of perceived effort, we demonstrated the involvement of the supplementary motor area and midcingulate cortex in effort perception. These findings suggest that additional neural resources are recruited to maintain performance during pain and that the supplementary motor area and midcingulate cortex contribute to heightening the effort experienced.

neuroscience↗

bioRxiv2026

The central motor command, but not the muscle afferent feedback, is necessary to perceive effort

Two theoretical models are proposed on the signal processed by the brain to generate the perception of effort (PE): the corollary discharge model and the afferent feedback model. To test the validity of these models, we used electromyostimulation to manipulate the magnitude of the central motor command during voluntary (high motor command), evoked (no motor command) and combined (low motor command) contractions at similar torque outputs. As electromyostimulation evokes sensory volleys to the central nervous system, it was used to evoke muscle contractions and to stimulate afferent feedback. We hypothesized that PE would reflect the magnitude of the central motor command and that evoked muscle contractions in the absence of central motor command would not elicit any PE. Twenty participants (n=10 experienced and n=10 novice with electromyostimulation) volunteered in this study. Participants reported their PE after isometric (10% and 20% MVC) and dynamic (5% and 20% MVC) voluntary, evoked, and combined contractions. For the same torque, participants reported no PE during evoked contractions, but all reported PE during voluntary contractions. Experienced but not novice participants reported lower PE during the combined than during voluntary contractions. This study questions the validity of the afferent feedback model and highlights the key role of motor command-related signals in PE generation. However, results from the novice participants during the combined contractions suggest that other factors such as inhibitory control may affect PE. Future studies should investigate the relationship between the central motor command and PE during physical tasks at various levels of complexity.

neuroscience↗

bioRxiv2021

Pharmacological blockade of muscle afferents and perception of effort: a systematic review with meta-analysis

BackgroundThe perception of effort (PE) provides information on task difficulty and influences physical exercise regulation and human behavior. This perception differs from other-exercise related perceptions such as pain. There is no consensus on the role of group III-IV muscle afferents as a signal processed by the brain to generate PE. ObjectiveThe aim of this meta-analysis was to investigate the effect of pharmacologically blocking muscle afferents on the PE. MethodsSix databases were searched to identify studies measuring the ratings of perceived effort (RPE) during physical exercise, with and without pharmacological blockade of muscle afferents. Articles were coded based on the operational measurement used to distinguish studies in which PE was assessed specifically (effort dissociated) or as a composite experience including other exercise-related perceptions (effort not dissociated). Articles that did not provide enough information for coding were assigned to the unclear group. ResultsThe effort dissociated group (n=6) demonstrated a slight RPE increase with reduced muscle afferents feedback (standard mean change raw (SMCR), 0.39; 95%CI, 0.13 to 0.64). The group effort not dissociated (n=2) did not reveal conclusive results (SMCR, -0.29; 95%CI, -2.39 to 1.8). The group unclear (n=8) revealed a slight RPE decrease with reduced muscle afferents feedback (SMCR, -0.27; 95%CI, -0.50 to -0.04). ConclusionsThe heterogeneity in results between groups reveals that the inclusion of perceptions other than effort in its rating influences the RPE scores reported by the participants. The absence of decreased RPE in the effort dissociated group suggests that muscle afferents feedback is not a sensory signal of PE. Key pointsO_LITo date, there is no consensus on the neurophysiological signal processed by the brain to generate the perception of effort. C_LIO_LIFollowing a systematic search in six databases, this meta-analysis suggests that reducing afferent feedback from the working muscles via epidural anesthesia does not reduce perception of effort. C_LIO_LIThis systematic review suggests that afferent feedback from the working muscles is not the neurophysiological signal processed by the brain to generate the perception of effort. C_LI

neuroscience↗