Reduced Theta and Alpha power during autobiographical memory retrieval in an individual with Highly Superior Autobiographical Memory

Individuals with highly superior autobiographical memory (HSAM) represent a rare population with exceptional ability to recall autobiographical information with remarkable precision. While research started to explore the neural mechanisms underlying this extraordinary memory, the role of theta and alpha oscillations—critical for autobiographical memory (AM) recall in the general population—has not yet been investigated in HSAM individuals. Midfrontal theta activity has been associated with control processes such as the effortful search of stored memories, while posterior alpha oscillations are thought to reflect the suppression of irrelevant sensory inputs, facilitating the efficient reliving of vivid mental imagery. Here, we studied a rare individual with HSAM and 16 controls, asking them to retrieve AMs during electroencephalographic (EEG) recording. Subjects had to press a response button to indicate "access/construction" of their AM and to continue "elaborating/reliving" it afterward. We focused on midfrontal theta oscillations during the access/construction phase of AM retrieval and posterior alpha oscillations during the elaboration/reliving phase. Our results showed that compared to controls, the HSAM participant exhibited both lower midfrontal theta power during the access/construction phase, and lower posterior alpha power during the elaboration/reliving phase. This reduced activity may reflect greater neural efficiency in HSAM individuals, enabling more direct access to AM and more vivid elaboration of such memories with less reliance on oscillatory mechanisms typically involved in memory retrieval. Specifically, lower midfrontal theta power may indicate that the HSAM individual required fewer control processes during the access/construction phase, potentially due to the automaticity of their memory retrieval. Similarly, reduced posterior alpha power during the elaboration/reliving phase could suggest a decreased need for sensory suppression and enhanced vivid mental imagery. These findings shed light on the unique neural dynamics underlying HSAM individuals and offer insights into how this phenomenon may be supported by more efficient cognitive processes.