How Self-processing Affects Mental Time Travel: a Neuropsychological Study

Mental Time Travel (MTT) is the ability to project oneself toward another specific temporal location, in the past or future subjective time. Specifically, it requires placing mental events on a subjective timeline by remembering the past or imagining the future. Regarding neural correlates, the subjective experience of remembering the past is associated with the lateral parietal cortex, especially in the inferior parietal lobule (IPL). The involvement of parietal areas in MTT for past events has been confirmed by neuropsychological and neuromodulation studies. Patients with neglect, following a lesion of the right parietal cortex, show a deficit in judging events that occurred before a specific temporal reference, suggesting an impairment in the representation of past events. Using transcranial alternate continuos stimulation (tACS) D'Angelo and colleagues (2023) showed that parietal beta frequencies selectively alter participants' ability to project into the past, but not into the future. Regarding future processing, the involvement of prefrontal cortex has been widely reported. The dorsolateral prefrontal cortex (dlPFC) plays a key role in planning, while the ventromedial prefrontal cortex (vmPFC) is involved in future scenario construction. In addition, vmPFC patients are unable to project into the future and anticipate events ahead, supporting a crucial role of the vmPFC in future construction.

Parietal and prefrontal areas are also involved in the processing of self-related information. In particular, the right lateral parietal cortex is more involved in retrieving self-related information than other-related information. Regarding the role of prefrontal regions in processing the self, the vmPFC shows greater activity when imagining a mental scenario related to the self rather than to another person.

To better understand MTT ability, two important questions arise from the review of the relevant literature. First, does self-related information affect our ability to mentally travel in time? If so, may these two processes interact in the same brain areas? VmPFC might be a good candidate for the interaction between future projection and self-processing: self-related stimuli could increase one's ability to "move" to future MTT.

Regarding past and self-related processing, the role of the right lateral parietal cortex is still unclear. IPL neural activity could underlie both processes, thus revealing a crucial centre for the interplay between MTT past projection and self-processing (autobiographical component of MTT).

The purpose of the present study is to investigate the influence of self-related stimuli in MTT tasks in patients with focal brain injury. Specifically, the authors will test for the first time whether the temporal distance between present time and the likelihood that a life event will occur (or has already occurred) is different whether the event is referred to one's own face or someone else's face.