Florent Meyniel (PhD)

Florent Meyniel is now a principal investigator at NeuroSpin, CEA-Paris-Saclay, France.

(Current Homepage)

Summary of the Master 2 and PhD work (2009 - 2013)

How the human brain allocates physical effort over time: evidence from behavior, neuroimaging and pharmacology

No pain, no gain: optimal decisions involve a tradeoff between cost and benefit. We propose that in physical effort allocation, this tradeoff unfolds over time. We developed a task to investigate this process in the laboratory with healthy humans and a computational model to account for decisions to stop and resume the effort, and to disentangle the weights of cost and benefit in this process.

In this model, costs increase during exertion, due to fatigue at all stages of the motor command and decrease during rest, due to recovery. We showed that this dynamic may be captured by a cost-evidence variable and compared to the expected benefit. Decision to stop is triggered when cost-evidence reaches a pre-defined upper bound, and conversely, effort resumption is triggered when cost-evidence reaches a lower bound.

Our functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) studies complementarily showed that cost-evidence may be monitored in proprioceptive regions of the brain: posterior insula and ventro-medial thalamus [1]. MEG also showed that motor beta (13-30 Hz) desynchronization mediates the effect of incentives to hasten effort resumption [2]. This goal-directed invigoration of rest translate in a behavioral dissociation: the expected utility, and not the actual utility, modulates rest durations. Together, our results support the view that the behavior is adapted on the fly to cost-evidence levels and that this mechanism is modulated by the expected cost and benefit [3].

This effort allocation behavior was affected by selective serotonin reuptake inhibitor (Escitalopram) and not by pain killers (hypnosis or paracetamol).

This work bridges a gap between sport medicine, value-based decision-making and accumulation models in neuroscience in showing that accumulation and dissipation of cost-evidence can guide the optimization of effort allocation: this mechanism implements the maximization of benefit while the body costs are minimized.

Related publications

[1] Meyniel, F., Sergent, C., Rigoux, L., Daunizeau, J., and Pessiglione, M. (2013). Neurocomputational account of how the human brain decides when to have a break. Proc. Natl. Acad. Sci. U.S.A. 110, 2641–2646.

[2] Meyniel, F., and Pessiglione, M. (2014). Better Get Back to Work: A Role for Motor Beta Desynchronization in Incentive Motivation. J. Neurosci. 34, 1–9.

[3] Meyniel, F., Safra, L., and Pessiglione, M. (2014). How the brain decides when to work and when to rest: dissociation of implicit-reactive from explicit-predictive computational processes. PLoS Comput. Biol. 10, e1003584.

A popular science article that summarizes these findings (in French):

Meyniel F. (2014) Au bout de l'effort. Cerveau & Psycho. 62, 76-79