Mental time travel (MTT) refers to the ability to project oneself backward into the past or forward into the future to envision past and future events. This study examines the role of the ventromedial prefrontal cortex (vmPFC) in orienting toward past and future events during MTT.
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.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
66
A psychophysical task (D'Angelo et al., 2023) will be adopted. In this task, a projection in time will be "induced" by faces of different ages. Face stimuli will be presented with a short sentence describing a particular life event, commonly occurring around 60. Participants will perform a two-alternative forced-choice task under two experimental conditions. In the "past projection" condition, they will indicate whether it is "likely" or "unlikely" that the person of the face shown could have experienced the indicated event 10 years earlier. In the "future projection," they will indicate whether it is "likely" or "unlikely" that the person depicted will experience the indicated event in 10 years.
In this task participants will estimate the age of the faces adopted as stimuli.
Istituti Clinici Scientifici Maugeri
Castel Goffredo, Mantova, Italy
RECRUITINGLikely Responses of events (Percentage)
If the vmPFC plays a crucial role in MTT, by activating and orienting to general knowledge about common life events, then vmPFC patients' probability judgments (% Likely Responses) in the MTT task should not be modulated coherently as a function of the perceived age of the portrayed faces and the Past vs. Future Projection condition. Considering the prominent role played by the vmPFC in future-oriented cognition, we expect that deficits in MTT would be more marked in the Future compared to the Past Projection condition.
Time frame: At baseline
Temporal estimation of cultural prototypical life event (years)
The deficit found in MTT may be related to an impairment in activating general knowledge about common events. If this is the case, it should also result in an impairment in temporally placing cultural events appropriately on a time-line representing the duration of life (in years, from birth to death). Moreover, these difficulties in the temporal ordering of life events would be more marked for relatively future compared to relatively past events.
Time frame: At baseline
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In this task participants will be instructed to associated each event with the age at which they believe it typically occurred.