EEG markers of TMS-induced brain plasticity in the adult speech system

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Despite tremendous progress in understanding the neural speech system, several questions remain regarding the organization of this system and its evolution over the adult lifespan. Despite a normal decline of structure and functions with age, the healthy adult brain retains a remarkable capacity to modify its structure and organization across the entire lifespan. This phenomenon is known as experience-dependent brain plasticity. One method to induce brain plasticity is through the use of a device called “repetitive transcranial magnetic stimulation” or rTMS. rTMS delivers magnetic stimulation to specific brain areas and can modify their functioning, which can enhance speech performance (e.g., speech perception, articulation, speech rate). When combined with electrophysiological techniques, such as EEG, it is possible to visualize and measure the effect of rTMS on brain activity. The objective of this grant is to acquire electrophysiological equipment to be able to study the effect of rTMS on brain activity. Specifically, we will purchase a TMS-compatible electroencephalography (EEG) and 2-channel auditory brainstem recording (ABR) system. The EEG system will allow my team and I to explore the effect of baseline neural activity on the impact of TMS and to document the nature and time course of TMS effects on brain activity at rest and during speech tasks. The ABR system will allow us to study lower-level subcortical auditory potential, which plays an important part in speech comprehension. Adding these measures to our projects will have a considerable effect on their impact and originality. This is because we are currently limited to measuring the impact of TMS on performance and have no equipment to measure the rTMS effects on brain activity. A set of studies will be conducted focusing on applying rTMS to different regions of the speech system to enhance specific speech functions. In each study, EEG and ABR will be recorded and examined to understand how rTMS alters brain activity in young and older adults and, in turn, how changes in neural activity influences speech performance. This research program will advance current knowledge of experience-induced plasticity mechanisms in the healthy younger and older adult brain. This knowledge will contribute to the development of brain-enhancing technologies, which are being developed across the world in the absence of adequate scientific and theoretical support. In addition to strengthening my research program, this equipment will provide new opportunities to involve undergraduate students in basic neuroscience research. It is currently difficult for me to allow undergraduate trainees to develop small independent projects because our main methodologiesMRI and TMSrequire acquiring costly MRI data. In contrast, EEG is free after the initial purchase. The availability of this equipment will also facilitate graduate student recruitment by expanding and diversifying my research capacity significantly.