LaPsyDÉ

Cognitive training, morphometry and resting-state functional connectivity in school-aged children

Supervised by Arnaud Cachia

Abstract:

Inhibitory control (IC, a set of neurocognitive control and behavioral abilities allowing us to resist temptations, distractions but also motor and cognitive automatisms) is a core process of cognitive development. Predictor of later professional success, physical and mental health, IC is also critical for academic successes. Relying on the intrinsic maturation of the prefrontal cortex (PFC), IC has a protracted development from childhood to early adulthood. A number of training interventions have already been designed to improve IC and reported encouraging results, as early as in preschool age. A short-term cognitive training could change the brain, at both structural and functional levels. However, results in the literature still remain controversial. The aim of this thesis was to better capture anatomical and functional brain changes paralleling the behavioral changes subsequent to a targeted IC cognitive training. We used a longitudinal design to investigate the effects of an intensive individualized adaptative computerized training (25 sessions, 15min/day, 5 weeks) in 64 healthy children (9,8± 0,56 y.o), randomly assigned to an IC (i.e., Color-Word Stroop and Stop-Signal tasks, n=32) or an active control (i.e., knowledge- and vocabulary- based tasks, n=32) training group. A cognitive assessment and a multimodal MRI acquisition were performed before and after the training. In STUDY 1, we investigated the effects of the cognitive training at behavioral level. Only children assigned to the IC group progressed between the pre- and post-training sessions. Further analyzes showed that both gender and basal IC efficiency modulated this effect. In STUDY 2, we analyzed the anatomical CPF changes and specified the developmental effects by comparing the results with those obtained in an adolescent group (n=59, 16 y.o). Similarly to neuroplastic mechanisms occurring during brain development, we found age- and gender-specific changes of cortical thickness and surface area in many CPF sub-regions after training. In STUDY 3, we investigated the functional cerebral changes from a resting-state functional connectivity (rs-FC) analysis. In order to reduce biases related to head-motion, particularly important during acquisitions with children, we used a multi-echo (ME) resting-state fMRI sequence. In pre-training, we found a stronger rs-FC between the right medial PFC and the left central opercular PCF associated to lower IC performance. The specific training effect - measured by the group (CI vs. CA) x time (pre- vs post-training) interaction - was associated to a rs-FC change between right opercular PFC and middle temporal gyrus. Taken together, our results in school-aged children support that cognitive changes related to an IC training are underlain by anatomical and rs-FC PFC changes.