Maintenance of tactile short-term memory for locations is mediated by spatial attention

Abstract

According to the attention-based rehearsal hypothesis, maintenance of spatial information is mediated by covert orienting towards memorized locations. In a somatosensory memory task, participants simultaneously received bilateral pairs of mechanical sample pulses. For each hand, sample stimuli were randomly assigned to one of three locations (fingers). A subsequent visual retro-cue determined whether the left or right hand sample was to be memorized. The retro-cue elicited lateralized activity reflecting the location of the relevant sample stimulus. Sensory processing during the retention period was probed by task-irrelevant pulses randomized to locations at the cued and uncued hand. The somatosensory N140 was enhanced for probes delivered to the cued hand, relative to uncued. Probes presented shortly after the retro-cue showed greatest attentional modulations. This suggests that transient contributions from retrospective selection overlapped with the sustained effect of attention-based rehearsal. In conclusion, focal attention shifts within tactile mnemonic content occurred after retro-cues and guided sensory processing during retention.