Assessing cTBS virtual lesioning effects on parietal cortices and its ability to shift spatial attention

Abstract

Theta burst stimulation (TBS) is being considered as a potential treatment for spatial neglect by restoring the normal balance of interhemispheric inhibition across right / left posterior parietal cortices (PPC). Recent studies suggest the observed hyperactivity of the left hemisphere may result from neuroplastic change, rather than a release of inhibition. The present study investigates attentional theories in healthy individuals by administering continuous-TBS to induce a virtual lesion and probing excitability connections of the PPC to the contralateral primary motor cortex (M1) bilaterally, using twin coil transcranial magnetic stimulation (TMS). Any behavioural changes from pre/post cTBS will be assessed by the landmark task and the bilateral perceptual decision making paradigm. Preliminary data suggests cTBS altered spatial attention in individuals with initial pseudoneglect, whilst any effect on PPC excitability levels is currently inconclusive. In conclusion, these results may have implications for cTBS effectiveness whilst also aiding further knowledge on the effects of cTBS on the contralateral unstimulated hemisphere. As cTBS was effective in altering spatial preference immediately, it is possible that spatial neglect arises due to a release of inhibition to the left PPC rather than due to neuroplasticity changes.