Motivational fatigue: A neurocognitive framework for the impact of effortful exertion on subsequent motivation

Abstract

Fatigue - a feeling of exhaustion arising from exertion - is a significant barrier to successful behaviour and one of the most prominent symptoms in primary care. During extended behaviours, fatigue increases over time, leading to decrements in performance in both cognitively and physically demanding tasks. However, to date, theoretical accounts of fatigue have not fully characterised the neuroanatomical basis of cognitive and physical fatigue nor placed results within broader discussions of the functional properties of the systems implicated. Here, we review recent neurophysiological and neuroimaging research that has begun to identify the neural mechanisms underlying changes in behaviour occurring due to fatigue. Strikingly, this research has implicated systems in the brain, including the dorsal anterior cingulate cortex (dACC), anterior insula, and lateral prefrontal cortex, that in separate lines of research have been linked to motivating the exertion of effort, to persisting towards goals and to processing one's internal states. We put forward a neurocognitive framework for fatigue and its impact on motivation. Levels of fatigue arising from effortful behaviours impact on processing in systems that weigh up the costs and benefits of exerting effort. As a result, as levels of fatigue rise, the value of exerting effort into a task declines, leading to reductions in performance. This account provides a new framework for understanding the effects of fatigue during cognitively and physically demanding tasks as well as for understanding motivational impairments in health and disease.

Resilience during uncertainty? Greater social connectedness during COVID‐19 lockdown is associated with reduced distress and fatigue

“…These associations have been suggested in public health data previously in very specific samples, for example, how fatigue and stress intersect in healthcare workers, teachers, or prison staff (Burke, Greenglass, & Schwarzer, 1996;Cho et al, 2019;Keinan & Malach-Pines, 2007), but never in a representative sample that is in its entirety impacted by a common stressor. The findings support a view that although fatigue can have different sources including inflammation, physical exertion, mental exertion, and stress, it has a common consequence-a reduction in levels of activity (Afari & Buchwald, 2003;Draper et al, 2018;Hockey & Hockey, 2013;M€ uller & Apps, 2019). Our findings point to a partially psychological foundation of fatigue that can be mediated by specific worries and is linked to social connectedness.…”

Pharmacological evidence for the implication of noradrenaline in effort

“…Along the same lines, the amount of force produced by the monkeys (vigor) decreased over time, which was probably related to satiety and/or fatigue. Even though our task was not designed to study fatigue, we cannot exclude an interaction between fatigue and effort [80], but this could be addressed in future studies.…”

Causal role of lateral prefrontal cortex in mental effort and fatigue

“…The current study aimed to dissociate these conflicting accounts by testing how disrupting DLPFC functioning with noninvasive stimulation changes the motivation to exert effort. DLPFC has also been related to the feeling of fatigue, which is characterized by a lower willingness to engage in effort as a consequence of enduring exertion of high mental effort (Muller & Apps, 2019). Motivational fatigue after enduring work was reported to result in lower DLPFC activation, which in turn reduces the capacity to exert cognitive control (Blain et al, 2019;Blain, Hollard, & Pessiglione, 2016).…”