The Relationships Between Neural Correlates of Effort Perception and Physical Activity Engagement

Functional MRI Protocols for Studying the Neural Correlates of Effort Perception and the Effects of Targeted rTMS Protocols on Perceived Effort and Effort-based Decision-making

Objectives and research hypothesis Physical inactivity is a major health concern that has been linked to a variety of chronic diseases, including obesity, diabetes, cancer, cardiovascular diseases, and mental disorders. Recent studies have shown that regular physical activity can decrease the risk of SARS-CoV-2 infection, and severe COVID-19 illnesses, as well as improve antibody response to vaccine. As such, the adoption of a physically active lifestyle carries potential health benefits and has even been referred to as a "miracle cure" by the Academy of Royal Medical Colleges. Despite the implementation of policies that aimed to encourage regular physical activity, the prevalence of insufficient physical activity in high-income countries has increased since 2001 (32% in 2001 vs. 37% in 2018). Given the limited impact of health policies on physical activity engagement, it is essential to explore other avenues of research that can contribute to understanding this high level of inactivity and driving innovative strategies for encouraging physical activity. In this context, the automatic attraction of individuals toward activities associated with low-effort exertion is thought to play a key role in physical inactivity. Physical activity involves exerting physical effort, i.e., intensifying physical energy to achieve certain goals, such as increasing the force to lift a heavy object. This physical intensification is associated with the phenomenological experience of energy exertion. Higher effort perception is thought to be aversively valued by inactive individuals, inhibiting their engagement in regular physical activity. However, there is a lack of knowledge regarding the neural correlates of effort perception and how they relate to physical inactivity. It is crucial to gain insights into these neural correlates, especially to enhance our comprehension of the significance of effort minimization in physical inactivity. This project aims to decrease effort perception and improve the valuation of effort, incentivize regular physical activity, and improve overall health outcomes.

Objective 1. Despite ongoing research, there is a lack of agreement on the neural mechanisms underlying effort perception as well as the role of sensorial feedback. Tasks EEG and fMRI aim to address this issue with original experimental methods in order to identify this neural mechanism.

Hypothesis 1. Following A) muscle vibration and B) Induced ischemic paralysis and anesthesia, we expect decreased effort perception associated with a lower cortical S1 activation, unchanged activation in premotor structures, and preserved functional connectivity between premotor regions and S1.

Objective 2. To unravel the neural interaction between efference copy and reafferent muscle spindle signals that contribute to effort perception Hypothesis 2. The neural correlates of effort perception involve interactions between premotor and sensory brain structures. Neural activation patterns of the brain regions implicated in effort perception vary depending on an individual's inclination to engage in physical activity.

Objective 3. Task 3 will examine the potential of non-invasive brain stimulation techniques (TMS) to reduce effort perception in turn increase its perceived value quantified with the CR100 scale, the outcome variable of this study.

Hypothesis 3. Vibration-induced desensitization of muscle spindles and the SMA cTBS reduce effort perception and improve the subjective value of physical effort.

Our society is currently facing a pandemic of physical inactivity that is responsible for numerous chronic diseases and deaths. Despite the implementation of policies aimed at encouraging regular physical activity, the prevalence of physical inactivity remains high. It then seems necessary to explore other areas of research that could explain this level of inactivity and guide the implementation of new strategies to make the population more active. In this context, the tendency of most individuals to gravitate towards activities associated with a low perception of effort seems to play a central role in many barriers to engaging in physical activity. The perception of effort, which refers to the perception of the physical resources invested in a physical task, seems to be evaluated aversively by inactive individuals, limiting their engagement in physical activity. However, the neuropsychological bases of effort perception and how they are involved in physical inactivity remain poorly understood today. Therefore, clarifying the neural substrates involved in this perception and understanding how they determine engagement in physical activity is essential to help increase the population's level of physical activity. The hypothesis guiding this project is that reducing the perception of effort so that a particular intensity physical activity is perceived as less demanding facilitates engagement and the maintenance of a physically active lifestyle. In this context, the primary objective of this project will be to clarify the neural substrates involved in the perception of effort through a functional MRI study and to identify whether neuropsychological mechanisms related to the perception of effort differentiate individuals who have an aversion or an attraction to physical activity. Based on these results, the second objective will be to evaluate whether repetitive transcranial magnetic stimulation techniques targeting key nerve structures and reducing the perception of effort improve the value of effort and engagement in regular physical activity.

Inclusion Criteria:

• Normal subjects all ranges age
• Exclusion Criteria:
• Neurologic conditions that may bias the EEG or fMRI results such as epilepsy, tumors; stroke; which can be a casual MRI finding during the study.