Abstract
The content of visual working memory (VWM) can be decoded robustly in both human occipito-temporal cortex (OTC) and posterior parietal cortex (PPC). Further work revealed that VWM signal in OTC is largely sustained by feedback from associative areas such as PPC. This raises an intriguing question: What information is retained in OTC during VWM delay? Does it reflect the sustained sensory information initially encoded in OTC or feedback information received from regions like PPC? To examine this, this study took advantage of a previous finding showing that object representational structure (measured from fMRI response patterns) differs between the OTC and PPC during perception. If VWM representation reflects the sensory information encoded during perception, then object representational structure should remain distinct between OTC and PPC during VWM delay. To investigate this, in this fMRI study, twelve human participants retained in VWM objects from eight categories, including bodies, cars, cats, chairs, elephants, faces, houses and scissors. The object representational structure correlation between OTC and PPC was found to be greater during VWM delay than during perception, suggesting that object representations become more similar between these two brain regions during VWM delay. Furthermore, the object representational structure correlation between perception and VWM delay within a region was greater in PPC than OTC, showing that object representation undergoes a greater amount of change in OTC than PPC between perception and VWM delay. Lastly, the object representational structure from OTC during VWM delay was more correlated with that of PPC during perception than with itself during perception, further indicating that OTC object representation during VWM delay becomes more aligned with those of PPC during perception. Together, these results show that the content of VWM representation in OTC is determined more by the feedback signal from PPC than by the sensory information initially encoded in OTC.