Cortico-cortical interactions in spatial attention: A combined ERP/TMS study

Abstract

To gain insight into the neural basis of visual attention, we combined transcranial magnetic stimulation (TMS) and event-related potentials (ERPs) during a visual search task. Single-pulse TMS over right posterior parietal cortex (rPPC) delayed response times to targets during conjunction search, and this behavioral effect had a direct ERP correlate. The early phase of the N2pc component that reflects the focusing of attention onto target locations in a search display was eliminated over the right hemisphere when TMS was applied there but was present when TMS was delivered to a control site (vertex). This finding demonstrates that rPPC TMS interferes with attentional selectivity in remote visual areas.

Fig. 1

Mean normalised response times (RT ± S.E.) for target-absent and target-present trials with TMS applied over rPPC or vertex.

Fig. 2

Grand-averaged ERPs elicited at right posterior electrodes P8 and PO8 in response to arrays containing a target in the contralateral (left; dashed lines) or ipsilateral (right, solid lines) visual field. A: TMS over vertex. B: TMS over rPPC.