Abstract
The sensory recruitment account of working memory (WM) assumes that the short-term retention of visual or tactile stimuli is implemented by cortical areas that are also responsible for the perceptual processing of these stimuli. Focal attention supports the short-term retention of sensory information, but it is unknown whether attention can also be flexibly shifted between visual and tactile WM representations. This study explored such inter-modal attention shifts in a task that required memory for simultaneously presented tactile and visual stimuli. A set of bilateral tactile and visual sample stimuli was followed after a retention period by a set of test stimuli. In different blocks, participants were instructed to memorize all stimuli on either the left or the right side. An auditory retro-cue, presented 500 ms after the sample sets, signalled whether the tactile or visual stimuli were relevant for the upcoming memory test. To study how these cues affect tactile and visual short-term storage, we measured the visual contralateral delay activity (CDA component) of the event-related potential (ERP) and its tactile counterpart (tCDA) that are elicited over modality-specific visual and somatosensory cortex. Scalp current density transforms were used to minimize volume-conduction, and to simultaneously measure these components over somatosensory and visual regions of interest (ROIs). A significant ROI x cued modality interaction demonstrated that visual and tactile WM was affected by the cued task-relevance of these sensory modalities. The tCDA component over somatosensory scalp regions was present only when touch was cued. The CDA over visual cortex was present in both cueing conditions, but was larger when vision was cued. Our results suggest that tactile and visual stimuli are stored separately in modality-specific memory systems. We conclude that retro-cues elicit inter-modal attention shifts that selectively activate information in the currently task-relevant modality.
Meeting abstract presented at VSS 2015