Speech Motor Learning and Retention (Aim 2)

The overall goal of this research is to test a new model of speech motor learning, whose central hypothesis is that learning and retention are associated with plasticity not only in motor areas of the brain but in auditory and somatosensory regions as well. The strategy for the proposed research is to identify individual brain areas that contribute causally to retention by disrupting their activity with transcranial magnetic stimulation (TMS). Investigators will also use functional magnetic resonance imaging (fMRI) which will enable identification of circuit-level activity which predicts either learning or retention of new movements, and hence test the specific contributions of candidate sensory and motor zones. In other studies, investigators will record sensory and motor evoked potentials over the course of learning to determine the temporal order in which individual sensory and cortical motor regions contribute. The goal here is to identify brain areas in which learning-related plasticity occurs first and which among these areas predict subsequent learning.

The focus of this registration is Aim 2. Specific Aim 2 assesses the temporal order in which plasticity occurs in cortical motor and sensory brain areas during speech motor learning. Plasticity is assessed using measures of cortical excitability. Specifically, auditory, somatosensory and motor evoked potentials are elicited using single pulse TMS (motor), pure tone bursts (auditory), and mentalis nerve stimulation (somatosensory). Tests of cortical excitability are interleaved with trials involving speech motor adaptation. Cortical excitability is also measured using these same measures 24 hours after learning to assess retention. The Speech Motor Learning and Retention Master Protocol is NCT06467292.