Learning and development of endogenously-driven saccades – APPSAC

From birth, infants move their eyes to explore their environment and interact with it. These saccadic eye movements support their motor, cognitive and social skills they progressively acquire as they grow up. The development of oculomotor control in early childhood remains both poorly understood and quantified today. Paradoxically, a growing number of eye-tracking studies use eye movements as a window to cognitive and socio-cognitive processes in young children with typical development or with a developmental disorder. This growing research is particularly due to the fact that eye movements can be made by any child, including preverbal and nonverbal children, and to the significant advances in eye-tracking techniques. These studies use notably the adult oculomotor model to interpret the oculomotor behavior in children and thereby, make inferences about the underlying cognitive or socio-cognitive processes. But using the adult model may be inadequate because, for example, previous studies have shown that young children under the age of eight years generate inaccurate saccades compared to adults. In particular saccades in young children fall shorter of a simple visual target location than adults. Therefore, how to be sure that in a complex visual scene (for example a face), the locations where the children saccades land correspond to the positions they had selected and aimed at?
Through a behavioral approach in pre-school and school-aged children with a typical development, the goal of our basic research project is to fill the gap of knowledge in the control of voluntary (i.e. endogenously-driven) saccades and to establish a precise theoretical framework of this typical oculomotor development. The choice of voluntary saccades rests on their major contribution to daily cognitive tasks, to active visual perception involved in tasks such as reading, to the acquisition of fundamental knowledge and to social interactions. Moreover, these voluntary saccades are precisely those used by the researchers to probe the cognitive and socio-cognitive processes in children by means of eye tracking techniques. The project has two specific aims: 1) to determine whether baseline performance (amplitude, latency) of voluntary saccades improves with age as predicted by the developmental changes that occur in the brain, and 2) to determine when mechanisms of sensory-motor plasticity, namely saccadic adaptation, are in place and functional during development. These saccadic adaptation mechanisms, or sensori-motor learning mechanisms, are crucial throughout life because they constantly maintain our saccade performance, ensuring optimal interaction with our environment. The results of this project can be used as a baseline for a better understanding of the typical sensori-motor, cognitive and socio-cognitive development, and to pinpoint specific deficits associated with neuro-developmental and psychiatric disorders. The results can thus help with early diagnosis and rehabilitation, with important social implications at both clinical and educational levels.