Poster C42, Sunday, March 26, 5:00 – 7:00 pm, Pacific Concourse
Revealing unattended working memory representations with fMRI
Annelinde Vandenbroucke1,2, Derek Nee3, Elizabeth Lorenc2, Mark D'Esposito2; 1Donders Center for Cognitive Neuroscience, Rabdoud University Nijmegen, the Netherlands, 2UC Berkeley, California, USA, 3Florida State University, Florida, USA
When using working memory, we focus on a current item, while simultaneously storing relevant information for later use. In a previous study, we showed that visual cortex is engaged in storing stimulus-specific information when working on a current problem, while information that needed to be maintained for future use, but was currently not attended to, was neither actively maintained nor suppressed (see also Lewis-Peacock et al., 2012; LaRocque et al., 2013). This information might be maintained in an activity silent format, possibly through a change in synaptic weights (Mongillo et al., 2008; Stokes, 2015, Wolff et al., 2015). Research using monkey physiology and EEG has shown that when an unrelated neutral stimulus (impulse) is presented during memory maintenance, this silent representation can be revealed using the impulse evoked activity (Stokes et al., 2013; Wolff et al., 2015). In this study, we investigated whether this could be achieved with fMRI, and if so, where in the brain these silent representations could be read out. Participants remembered two orientations, of which one was currently-relevant, while the other was unattended and stored for future use. During the memory maintenance period, we presented a “bullseye” pattern that was unrelated to the task. This resulted in increased classification accuracy in early visual cortex during the maintenance period specifically for the unattended item. This finding suggests that the memory representation for this unattended item is maintained in visual cortex, albeit in a silent code that can be read-out from fMRI data using evoked responses.
Topic Area: EXECUTIVE PROCESSES: Working memory