Disruption of working memory and contralateral delay activity by nociceptive stimuli is modulated by task demands.

ABSTRACT Top-down processes allow the selection and prioritization of information by limiting attentional capture by distractors, and these mechanisms depend on task demands such as working memory (WM) load. However, bottom-up processes give salient stimuli a stronger neuronal representation and provoke attentional capture. The aim of this study was to examine the effect of salient nociceptive stimuli on WM while manipulating task demands. Twenty-one healthy participants performed a change detection task during which they had to determine whether two successive visual arrays were different or the same. Task demands were modulated by manipulating WM load (set size included 2 or 4 objects to recall) and by the correspondence between the two successive visual arrays (change versus no change). Innocuous stimuli (control) or nociceptive stimuli (distractors) were delivered during the delay period between the two visual arrays. Contralateral delay activity (CDA) and laser-evoked potentials (LEP) were recorded to examine neural markers of visual WM and nociceptive processes. Nociceptive stimuli decreased WM performance depending on task demands (all P< .05). Moreover, compared with control stimuli, nociceptive stimuli abolished the increase in CDA amplitude for set size 4 versus set size 2 (P= .04). Consistent with these results, LEP amplitude was not decreased when task demands were high (P= .5). These findings indicate that WM may shield cognition from nociceptive stimuli, but nociceptive stimuli disrupt WM and alter task performance when cognitive resources become insufficient to process all task-relevant information.