No abstract

How content is stored in the human brain during visual short-term memory (VSTM) is still an open question. Different theories postulate storage of remembered stimuli in prefrontal, parietal, or visual areas. Aiming at a distinction between these theories, we investigated the content-specificity of BOLD signals from various brain regions during a VSTM task using multivariate pattern classification. To participate in memory maintenance, candidate regions would need to have information about the different contents held in memory. We identified two brain regions where local patterns of fMRI signals represented the remembered content. Apart from the previously established storage in visual areas, we also discovered an area in the posterior parietal cortex where activity patterns allowed us to decode the specific stimuli held in memory. Our results demonstrate that storage in VSTM extends beyond visual areas, but no frontal regions were found. Thus, while frontal and parietal areas typically coactivate during VSTM, maintenance of content in the frontoparietal network might be limited to parietal cortex.

Items held in working memory can be either attended or not, depending on their current behavioral relevance. It has been suggested that unattended contents might be solely retained in an activity-silent form. Instead, we demonstrate here that encoding unattended contents involves a division of labor. While visual cortex only maintains attended items, intraparietal areas and the frontal eye fields represent both attended and unattended items.