Experimental and theoretical investigation of vigor dynamics in an ethological foraging task – Contribution of the dorsal striatum in setting effort sensitivity
Thomas Morvan
Team “Cortico-Basal ganglia circuits and Behavior”

Abstract
Animals (including humans) forage for food and water, and tend to optimize their behavior to obtain rewards as quickly as possible; they are willing to expend energy for this. This behavior is usually composed of two key steps, a first step of deliberation (fast deliberation saves time, but risks selection of a non-optimal choice), and a second step of movement toward the reward (running fast saves time, but is energetically costly). Interindividual sensitivities to effort (lazy vs. energetic), time (patient vs. impatient) and reward shape the optimality of this behavior. Recent studies suggest that the dorsal striatum controls action kinematics, but whether it contributes to setting effort, time and/or reward sensitivities is still unknown.
The goal of this study is therefore double. First, to better understand how time and effort influence simple foraging decisions and the speed of reward-oriented movements in freely moving rats. Second, to investigate whether the dorsal striatum could be involved in such processes. Here, we developed a foraging task in which freely-moving rats run on a motorized treadmill to get drops of water. We orthogonally manipulated the amount of effort they have to produce and the opportunities to obtain rewards; we relied on simple theoretical models to 1) quantify both the time it takes animals to initiate new crossings and their running speed, and 2) explore the computational logic and neurobiological determinants of vigor. This new paradigm allowed us to describe the dynamics of modulation of vigor during a foraging task, highlight stable behavioral traits specific to each rat, and assign a role to the dorsal striatum in the implementation of effort sensitivity.

Jury
Jérémie Naudé, Rapporteur – IGF,Montpellier
Matthieu Wyart, Rapporteur – EPFL SB IPHYS PCSL, Lausanne
Bastien Berret, Examinateur – Faculté des Sciences du Sport de l’Université Paris-Saclay
Marie-Laure Welter, Examinatrice – Institut du Cerveau, Hôpital Pitié-Salpêtrière, Paris
Claire Wyart, Examinatrice – Institut du Cerveau, Hôpital Pitié-Salpêtrière, Paris
Christophe Eloy, Co-directeur de thèse – IRPHE, Marseille
David Robbe, Directeur de thèse – INMED, Marseille

Monday 18 December 2023 at 2pm – Inmed conference room