Distinct generation of subjective vividness and confidence during naturalistic memory retrieval in the angular gyrus
Subjective experience of remembering is a hallmark of episodic memory, which is deemed crucial for effective behavior. A fundamental and enduring puzzle is the origin of confidence in memory; for example, does the confidence during episodic retrieval depend upon the subjective sensed vividness? The angular gyrus (AnG) exhibits a sensitivity to the subjective experience of remembering, but its direct contribution to the monitoring of subjective mnemonic experience has hitherto been lacking. Here, using a naturalistic video-watching paradigm combined with repetitive transcranial magnetic stimulation (rTMS) and resting-state functional magnetic resonance imaging, we found that pre-retrieval rTMS targeting the left AnG selectively alters the vividness efficiency compared to control stimulation while keeping metacognitive efficiency and objective memory accuracy unaffected. Using trial-wise data, we showed that AnG stimulation altered the mediating role of vividness in confidence in the accuracy of memory judgment. Furthermore, resting-state functional connectivity of hippocampus and AnG was specifically associated with vividness efficiency, while the connectivity of hippocampus and medial prefrontal cortex was associated with metacognitive efficiency across individuals. These findings identify the causal involvement of AnG in gauging the vividness, but not the confidence, of memory, thereby providing evidence for a differentiation account of conscious assessment of memory retrieval.
