A cortical hierarchical mechanism for subjective visual experience during working memory
Working memory allows the brain to simulate sensory experiences mentally. Studying individuals with aphantasia, who cannot voluntarily generate visual imagery yet perform normally on working memory tasks, reveals a cortical mechanism for subjective visual experience. Brain scans showed that in aphantasia, feedback signals along a pathway from the intraparietal sulcus through area V3AB to the early visual cortex are disrupted. The intraparietal sulcus showed impaired imagery signals and reduced connectivity with early visual cortex, which itself had a general deficit in receiving feedback. These impairments weakened delay-period representations and prevented the transition from visual to mnemonic codes. The findings indicate that this cortical hierarchy is essential for conscious mental visualization during working memory maintenance.