Attentional modulation of working-memory representations

Many higher-level cognitive functions critically depend on the ability to hold information in mind well beyond the offset of the initial sensory stimulation. Selective attention, the ability to focus cognitive resources on task relevant information, can influence working-memory performance, and current views emphasize a close relationship between WM and attention, both at the level of cognitive processes and underlying neural networks. Recent research has demonstrated that selective attention can bias representations already held in working memory, to adapt to changing task demands. Retrodictive cues presented during the retention period of a WM task are used to orient subjects’ attention to one or more representations within WM. Data from behavioral and functional magnetic resonance imaging studies will be presented showing a modulation of WM performance and of the maintenance-related brain activity as a function of the focus of attention. Maintenance-related activity in sensory cortices changed as an effect of attentional orienting towards the type of information represented in this area. Activity in associative parietal and prefrontal cortices was also biased by the retro-cue, but additionally exhibited a load-dependant interaction. In detail, the pattern of load-related activity after the retro-cue corresponded to the number of selected task-relevant mnenomic representations in the focus of attention and to behavioral WM performance, reflecting changes of the effective WM load. The data will be discussed with regard to the putative role of attentional top-down modulation on WM operations