The orienting of spatial attention in touch and pain: Evidence for modality-specific modulations of the cue-locked lateralized ERP components

The present study investigated whether lateralized event-related brain potential (ERP) components triggered during covert shifts of spatial attention (ADAN, LDAP, LSN) are selectively modulated by the cued modality of a forthcoming somatosensory target (pain vs. touch). ERPs were recorded during a cueing paradigm in which centrally presented visual cues provided information about the location (left vs right hand) and the modality (pain vs. touch) of the task-relevant target. Upon cue presentation, participants were instructed to covertly select the cued location and modality to respond to infrequent task-relevant targets, while ignoring uncued targets and all non-targets. Results showed the expected sequence of markers of anticipatory spatial attention reflecting preparatory activity within the anterior and posterior parts of the fronto-parietal attentional network. The anterior directing attention negativity (ADAN) observed over frontal electrodes was followed by the late directing attention positivity (LDAP) at posterior electrodes and by the late somatosensory negativity (LSN) at central electrodes. ADAN, LDAP and LSN were elicited regardless of the cued target modality, confirming the supramodal nature of the orienting mechanisms responsible for these lateralized components. Intriguingly, the LDAP was modulated by the cued modality with larger amplitudes when participants expected pain compared to touch. These findings are in line with recent evidence suggesting that the LDAP component is modulated by alerting mechanisms. We speculate that the enhanced LDAP amplitudes observed in the present study reflect stronger preparatory activity in anticipation of nociceptive events.