Grant: Canada Research Chairs

The overall goal of this interdisciplinary research program is to understand how brain senescence and experience-induced brain plasticity can shape the anatomy and functioning of the human adult brain and impact the ability to perceive and produce speech sounds -the basic building blocks of human communication. The first specific objective of this program is to study plasticity within the speech system and its impact on brain activity and speech performance in young and older adults, and to identify the sources of variability. To achieve these goals, several studies combining non-invasive brain stimulation (NIBS), behavioural measures of speech, language and hearing, and electroencephalography (EEG) will be conducted, each targeting a different component of the speech system. This work will quantify plasticity in the different components of the neural speech system and reveal whether age reduces plasticity in this system. The second goal is to characterize the nature and trajectory of structural and functional changes within and beyond the speech system and their relationship to speech production and perception performance through two longitudinal training studies combining NIBS, EEG and MRI. In each study, three groups of healthy young and older adults will be compared: speech training only, NIBS only, and combined training+NIBS. It is expected that NIBS will enhance and even fast-track the effect of speech training; the training+NIBS group will show higher gains more rapidly, especially the younger adults. Training will focus on enhancing speech perception and production. Finally, the third goal is to use the knowledge generated as part of the program to develop the first theory of speech that integrates the notion of antagonistic forces constantly at play: senescence and plasticity. The development of a realistic neurobiological model of speech functions will have a transformative effect by generating predictions that will guide empirical speech research and provide a framework for interpreting findings. By advancing knowledge about NIBS and brain plasticity, this program will stimulate methodological developments and accelerate research on cognitive aging. This knowledge could also lead to innovation in the industry of brain-enhancing technologies and cognitive stimulation, which are flourishing despite adequate scientific support. Such technologies can facilitate language learning, enhance communication skills and promote healthy aging.