Neural correlates of automatic attention in touch: event related potentials and behavioural measures

Exogenous orienting is when our attention is automatically driven by external stimuli, such as a tap on our shoulder. Behavioural studies of exogenous attention have demonstrated inhibition of return (IOR) in detection of tactile targets and mixed results in discrimination tasks. Event related potential (ERP) experiments of exogenous attention have highlighted possible neural correlates of IOR in vision, however, no previous study has investigated how exogenous tactile attention affects somatosensory processing. In the present study non-informative lateralized tactile cues followed by tactile targets were presented to the middle fingers and thumbs. Responses were made vocally and in experiment 1 participant’s simply detected targets whilst in experiment 2 they discriminated the location (thumb/index), regardless hand. Behavioural results showed IOR in the detection task whilst no attention effect in the discrimination task. ERPs from the two tasks showed an early (N80) enhanced negativity for uncued compared to cued targets suggesting exogenous attention affects early somatosensory processing. Overall ERP effects were similar in both tasks, however, similarly to P1 in vision, P100 attention effect may also be linked to IOR in touch as a contralateral P100 components was present in detection whilst absent in discrimination task. Further, analysis of cue-target interval showed anterior directed attention negativity (ADAN) previously only linked to endogenous attention which in turn may suggest endogenous and exogenous orienting are part of a shared orienting system.

15th Annual Meeting Portland Marriott Downtown Waterfront, Poster session abstracts, published Online First 25th August 2010