T127 THE INFLUENCE OF TRANSIENT SHIFTS OF SPATIAL ATTENTION ON ELECTROCUTANEOUS STIMULUS EVOKED POTENTIALS

Abstract

Background and Aims: Previous research revealed that processing of electrocutaneous stimuli is attenuated during sustained distraction tasks as compared to focused attention tasks, which is reflected in reduced N1 and P3a ERP components. Unknown, however, is whether transient shifts of spatial attention have the same attenuating effect. This issue was examined by employing a Posner‐cueing paradigm with electrocutaneous stimuli. Methods: Participants were presented with visual cues indicating the probable location (left or right forearm) of a to‐be‐discriminated electrocutaneous stimulus with a validity of 80%. Stimuli were of low or high intensity (manipulated by varying the number of pulses) and participants were instructed to make speeded responses depending on the perceived intensity by using two foot pedals. EEG was measured to determine the N1 and P3a ERP components. Results: Preliminary results show that knowledge of the probable forthcoming location of a stimulus affected the subsequent processing of this stimulus. Slower RTs were observed for invalidly cued as compared to validly cued stimuli. The N1 and P3a component were both enlarged for a high intensity compared to a low intensity stimulus. The N1 component was enhanced for attended as compared to unattended stimuli. In contrast, the P3a component, which is thought to reflect an orienting response, was enhanced for unattended as compared to attended stimuli. Conclusions: A transient manipulation of focused attention increases cortical activity for attended as compared to unattended electrocutaneous stimuli. Furthermore, initially unattended stimuli appear to induce an enhanced orienting effect.