Inhibitory control in macaque species

: validation of a task battery, individual differences in performance and effect of social tolerance

Abstract

Living in a complex social environment requires primates to manage their emotions and inhibit impulsive behaviours. The cognitive processes that underpin these behaviours, crucial in many aspects of everyday life, are defined as inhibitory control. In animal studies, the various paradigms designed to measure inhibitory control often suffer from a lack of systematic validation. Moreover, striking individual variations in inhibitory control performances are often largely ignored and their causes rarely considered. Finally, little is known about the selective forces that shape the evolution of inhibitory control. It has been suggested that one route by which this ability can be enhanced is through selection on social tolerance. Hence the aim of this project was three-fold: 1- to develop a battery of inhibitory control tasks in non-human primates 2- to use this task battery to systematically investigate individual variability and its most common causes 3-on a broader evolutionary scale, to compare the inhibitory control skills in three species which differ in social tolerance style. For that purpose, we tested 66 macaques (28Macaca mulatta, 19 M. fascicularis and 18 M. tonkeana) in a battery of touchscreen tasks assessing three main components of inhibitory control: inhibition of a distraction (using a Distraction task), inhibition of an impulsive action (using a Go/No-go task) and inhibition of a cognitive set (using a Reversal learning task). We found that all tasks were reliable and effective at measuring the inhibition of an impulsive and automatic response. We then demonstrated individual variations, sex and age differences in inhibitory control performances. Finally we demonstrated that the least tolerant species were poorer at controlling their emotions and impulsions compared to other species. Overall, this project will help to get more insight into the multifaceted structure and the evolution of inhibitory control in primates.

Date of Award	Mar 2022
Original language	English
Awarding Institution	University of Portsmouth
Supervisor	Marine Joly (Supervisor) & Bridget Marguerite Waller (Supervisor)