Modulation of midfrontal theta and posterior alpha during the construction and elaboration of autobiographical memories in individuals with highly superior autobiographical memory.

Individuals with highly superior autobiographical memory (HSAM) represent a rare population with the exceptional ability to recall autobiographical information with remarkable precision and detail. While research has begun to explore the neural mechanisms underlying this extraordinary memory performance, the role of brain oscillations has not yet been investigated in HSAM individuals. Here, we studied three individuals with HSAM and compared their results with 16 controls. We asked all participants to retrieve newer and older autobiographical memories (AMs) while their electroencephalogram (EEG) was being recorded. Participants were asked to press a button to indicate access and construction of their AM and to continue elaborating it. We focused on midfrontal theta oscillations during the construction phase of AM retrieval and posterior alpha oscillations during the elaboration phase. Compared to the controls, the HSAM participants exhibited greater theta during the retrieval of older as compared to newer AMs, and no increase of the initial posterior alpha during the elaboration phase power. These findings may reflect more efficient neural processes in HSAM individuals. Specifically, the selective midfrontal theta enhancement during retrieval of remote memories suggests a flexible engagement of control and inhibitory mechanisms, supporting complex memory construction. The lack of initial posterior alpha increase could indicate reduced cortical suppression and, speculatively, more vivid visual imagery during elaboration. These findings shed light on the unique neural dynamics underlying HSAM individuals and offer new insights into how their autobiographical memory is supported by highly efficient neuro-cognitive processes.