Neural mechanisms underlying the effects of physical fatigue on effort-based choice

Patrick S Hogan,Steven X Chen,Wen Wen Teh,Vikram S Chib

doi:10.1038/s41467-020-17855-5

Patrick S Hogan, Steven X Chen + Show 2 more

Open Access

https://doi.org/10.1038/s41467-020-17855-5

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Abstract

Physical fatigue crucially influences our decisions to partake in effortful action. However, there is a limited understanding of how fatigue impacts effort-based decision-making at the level of brain and behavior. We use functional magnetic resonance imaging to record markers of brain activity while human participants engage in uncertain choices for prospective physical effort, before and after bouts of exertion. Using computational modeling of choice behavior we find that fatiguing exertions cause participants to increase their subjective cost of effort, compared to a baseline/rested state. We describe a mechanism by which signals related to motor cortical state in premotor cortex influence effort value computations, instantiated by insula, thereby increasing an individual’s subjective valuation of prospective physical effort while fatigued. Our findings provide a neurobiological account of how information about bodily state modulates decisions to engage in physical activity.

Highlights

Physical fatigue crucially influences our decisions to partake in effortful action
Previous work has established a network of brain regions, including the anterior cingulate cortex (ACC), bilateral anterior insula, and ventromedial prefrontal cortex in computing the value of effortful options and making effort-based decisions[1,2,3,4,5,6,7,8,9,10]
We found a region of the right anterior insula was modulated by effort value during the fatigue choice phase (Fig. 3b; Supplementary Table 2), and appeared to be insensitive to chosen and unchosen effort value in the baseline/ rested state (Fig. 3c)

Summary

Introduction

Physical fatigue crucially influences our decisions to partake in effortful action. there is a limited understanding of how fatigue impacts effort-based decision-making at the level of brain and behavior. It has been suggested that such fatigue-induced decreases in motor cortical activity are a reflection of a reduced capacity for the recruitment of motor pathways within the central nervous system These previous works examined motor cortical physiology following fatiguing exertion and did not investigate how such motor cortical changes might influence the valuation of prospective effort and decisions to engage in physical activity. It has been proposed that feelings of fatigue may arise from inconsistencies between beliefs about the consequences of actions and actual sensory inputs and motor outputs[16,17,18] With this in mind, it has been suggested that brain networks that process proprioceptive and exteroceptive signals from muscles and interoceptive signals from the internal state of the body and visceral organs, could be critical for generating feelings of effort and fatigue. There is a limited mechanistic understanding of how neural signals related to perceptions and sensations of fatigue influence effort valuation and decisions to exert

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