Can tDCS enhance speech production skills?
Transcranial direct current stimulation (tDCS) can change neuronal excitability and enhance learning, for example in motor and language tasks. As such, tDCS has shown promise as a tool for neuro-rehabilitation. We are interested in using tDCS to improve speech skills. Activity in the left inferior frontal cortex is modulated during learning to articulate novel words (Rauschecker et al., 2008). Recently, we investigated whether tDCS over this area improves fluent speakers’ ability to learn to produce novel words. We found that anodal tDCS during training task resulted in increased accuracy in repeating words after training. However, when the task was combined with sham stimulation, training had no effect on repetition accuracy. Our results demonstrate that anodal tDCS of left inferior frontal cortex can improve learning of speech motor skills. We are now investigating how tDCS could be used to improve fluency in people who stutter.
Using sensory feedback during speaking
We are interested in how sensory feedback modulates fluency during speaking. It is well know that delayed auditory feedback impairs fluency. We have used functional MRI to examine the neural correlates of changes in speech production due to delayed feedback. Our recent behavioural study showed that delayed visual feedback (i.e., seeing one’s own articulatory movements) can also modulate fluency.