The Neural Basis of Visual Working Memory of Real-World Object

Sustaining visual information in mind temporally, denoted as visual working memory (VWM), is a core ability of many cognitive functions, such as decision making and problem solving. While existing evidence focusing on low-level features suggests that VWM recruits analogous regions utilized in perceptual tasks, the neural basis of real-world objects within VWM remains elusive. To address this, we investigated the representation of twenty real-world objects across three VWM and three perception tasks using fMRI. In experiment 1, twelve participants performed a retro-cue sequential VWM task, viewing two objects and recalling the cued object after a ten-second delay. We found the identity of the cued objects could be decoded from the lateral occipital complex (LOC) and intraparietal sulcus (IPS), but not in early visual areas. Moreover, representational similarity analysis (RSA) revealed a common representational pattern between VWM and perceptual tasks exclusively in the LOC, indicating that task-relevant high-level visual areas are specifically recruited for VWM maintenance. Experiment 2 leveraged the contralateral bias effect to assess the extent of shared representational properties between VWM and perception. Six participants performed a retro-cue spatial VWM task where they memorized a cued object from two objects presented in separate visual fields. Interestingly, while a strong contralateral bias was confirmed in the perception task, this bias was significantly reduced in the VWM task, evident through an enhanced ipsilateral representation of the cued object. Experiment 3 delayed the retro-cue to the end of the delay, resulting in persistent but significantly reduced involvement of the ipsilateral LOC. Additionally, searchlight RSA revealed larger cortical representational areas in VWM than perception tasks. These results underscore the essential role of both the LOC and IPS in maintaining real-world object representations in VWM, while the sensory-based object representations in high-level visual areas may go beyond the feedforward visual information flow during VWM.