The Temporal Unfolding of Event Construction while Thinking Aloud: Role of Ventromedial Prefrontal Cortex

Mental time travel (MTT), the ability to mentally project backward and forward in time, relies on navigating a hierarchical organization of mental representations, ranging from higher-level (semantic) to lower-level (episodic) knowledge structures. Ventromedial prefrontal cortex (vMPFC) is thought to initiate the activation of personal semantic information during MTT, but its precise role in the temporal dynamics of MTT remains unclear. In the present study, patients with focal vMPFC lesions, brain-damaged controls, and healthy participants completed a personal semantic interview followed by an MTT task in which they were instructed to remember past events and imagine future events while "thinking aloud," namely, uttering every information that came to their mind while constructing events. vMPFC patients showed degraded personal semantic information in the personal semantic interview compared with the control groups. In the MTT task, they generated more repeated events and fewer specific events than the control groups. Moreover, they exhibited atypical, "backward" transitions from lower-level (e.g., extended and repeated events) to higher-level (e.g., personal semantics) knowledge structures, indicative of an alteration of retrieval dynamics following vMPFC damage. These findings confirm that vMPFC damage impairs personal semantic memory and alters the retrieval dynamics of event construction, hindering access to specific events.