P 66. TMS entrainment of pre-stimulus oscillatory activity in tactile processing

Abstract

It is widely recognized that oscillatory activity plays an important functional role in neural systems. Decreases in alpha (∼10 Hz) EEG/MEG activity in the parietal cortex correlate with the deployment of spatial attention controlateral to target location in visual, auditory and tactile domains ( Bauer et al., 2012 , Foxe and Snyder, 2011 , Linkenkaer-Hansen et al., 2004 ). Recently, repetitive Transcranial Magnetic Stimulation (rTMS) has been successfully applied to entrain a specific frequency at the parietal cortex (IPS) and the visual cortex. A short burst of 10 Hz rTMS impaired contralateral visual target detection and improved it ipsilaterally, compared to other control frequencies ( Romei et al., 2010 ). This finding suggests a causal role of rhythmic activity in the alfa range in perception ( Thut et al., 2011 ). The aim of the present study is to address whether entraining alpha frequency in the IPS plays a role in tactile orienting, indicating similarities between senses (vision and touch) in the communication between top-down (parietal) and primary sensory areas (V1 or S1). We applied rhythmic TMS at 10 Hz and 20 Hz to the (right or left) IPS and S1, immediately before a masked vibrotactile target stimulus (present in 50% of the trials) to the left or right hand. Preliminary results lean towards the consequential effects of entraining alpha frequency into IPS for tactile detection such that it decreases tactile perception contralaterally and increases it ipsilaterally, compared to Sham. The results suggest the existence of a similar mechanism of orienting attention in vision and touch, therefore paving the way for further testing the role of parietal alpha band oscillation in other tactile information processing, such as in tactile remapping, a mechanism that allow our brain to localize tactile events in external space. European Research Council (StG-2010 263145).