Perturbing the pathway: The impact of lollipops and lidocaine on supramarginal gyrus activity during silent reading tasks.

INTRODUCTION

The effects of auditory perturbations on reading performance are well studied, but somatosensory perturbations are less understood. Recent research shows oral sensory perturbations (stimulation and anesthesia) improve reading performance in typical readers, though their neural impacts are unclear. This exploratory clinical study investigates how mouth perturbations affect supramarginal gyrus activity during silent reading in a group of typical readers.

METHODS

30 English-proficient adults completed orthographic and phonological lexical decision tasks under three conditions: no perturbation, sensory stimulation (lollipop in the mouth), and sensory anesthesia (lidocaine solution swished in the mouth). Functional Near-Infrared Spectroscopy (fNIRS) was used to measure cortical hemodynamic responses of the supramarginal gyrus and the posterior superior temporal gyrus.

RESULTS

Sensory anesthesia reduced supramarginal gyrus activity and facilitated silent reading speed in the phonological task, while accuracy remained unaffected. Sensory stimulation increased supramarginal gyrus activity but did not impact behavioural performance. Neither perturbation affected the activity of the posterior superior temporal gyrus. Both perturbations impacted functional connectivity between somatosensory and auditory cortices.

CONCLUSION

Taken together, these preliminary and modest effects suggest that oral somatosensory input influence reading-related brain activity and inter-regional connectivity. However, given the preliminary and clinical nature of this study, these findings are interpreted with caution. Ultimately, the importance of somatosensory feedback in reading warrants more targeted exploration to better our understanding of the relationship between speech-motor processes and reading ability.