# Behavioral and Neural Representations of Subjective Effort Cost

> **NIH NIH R01** · HUGO W. MOSER RES INST KENNEDY KRIEGER · 2024 · $721,889

## Abstract

PROJECT SUMMARY
Fatigue, a feeling of tiredness and exhaustion, occurs throughout life and significantly impacts our decisions to
engage in effortful daily activities. A wide range of neuropsychiatric and neurological disorders report fatigue as
either a symptom or comorbidity and are associated with disruptions in effort-based decision-making. Despite
the prevalence of fatigue in health and disease, there is a limited understanding of how fatigue evolves over
time and ultimately impacts effort-based decision-making. The goal of this proposal is to understand the
mechanisms that subserve the evolution of physical and cognitive fatigue through repeated exertion, and how
fatigue influences decision-making in healthy humans. Furthermore, we aim to understand how these
mechanisms are disrupted in individuals with major depressive disorders (MDD), of which fatigue is a cardinal
symptom. To this end, we will use a combination of experiments in human participants, computational modeling
of behavior, and functional magnetic resonance imaging (fMRI). Aim 1 we will investigate how the evolution of
fatigue influences the dynamics of effort-based decision-making. We will poll participants' momentary
subjective fatigue as they perform bouts of fatiguing exertion and make effort-based decisions. We will use
computational modeling to characterize participants' fatigue and test how this fatigue influences decisions to
exert. We will use model-based fMRI to examine how the brain integrates information about fatigue to drive
choice. In Aim 2, we will investigate how motivational state modulates feelings of fatigue and effort-based
decision-making. In this Aim we will pair fatiguing exertions with different levels of monetary incentive to
modulate participants' motivational state. This manipulation will allow us to study how motivation influences
feelings of fatigue and decisions to exert and the underlying neural mechanisms. In Aim 3, we will identify how
fatigue influences effort-based decision-making in individuals with MDD. Participants with MDD will undergo
fatiguing exertions, rate their feelings of fatigue, and make effort-based choices. We will examine how feelings
of fatigue and effort-based choice are related to MDD symptomology. In sum, our proposed studies will have a
broad impact on the field of decision-making by dissecting the behavioral and neural mechanisms responsible
for the influence of feelings of fatigue on physical and cognitive effort valuation. In the long term, these studies
may reveal novel behavioral and neural markers to aid in the study, classification, and treatment of fatigue.

## Key facts

- **NIH application ID:** 10880799
- **Project number:** 2R01MH119086-05A1
- **Recipient organization:** HUGO W. MOSER RES INST KENNEDY KRIEGER
- **Principal Investigator:** Vikram S Chib
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $721,889
- **Award type:** 2
- **Project period:** 2019-08-01 → 2029-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10880799

## Citation

> US National Institutes of Health, RePORTER application 10880799, Behavioral and Neural Representations of Subjective Effort Cost (2R01MH119086-05A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10880799. Licensed CC0.

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