Autobiographical Past and Future Thinking in Patientis with Temporal Lobe Epilepsy

Abstract

Autobiographical thinking involves vivid recollection of past and construction of future events, which contain episodic and non-episodic information. The events are situated in a specific spatiotemporal context and often contain sensory, perceptual and emotional details. Retrieving past and generating future events involves overlapping cognitive and neural mechanisms. According to the Constructive Episodic Simulation Hypothesis (CESH) relational processing and the hippocampi are critical for both recall of past and generation of future episodic information. Conversely, bilateral hippocampal damage has been shown to impair recall of episodic details from both temporal directions: past and future. Research involving patients with unilateral temporal lobe epilepsy (TLE) whose seizures typically emanate from the hippocampus has revealed impaired recall of past episodic details. Whether unilateral TLE also impacts generation of future episodic details, however, has not been investigated. In this study we examined past and future thinking in patients with a history of unilateral TLE (n=20) and control (NC) subjects (n=20). Patients with TLE were found to be impaired, relative to controls, in recall of episodic but not non-episodic details for past and future events. Further analyses of past and future events revealed that patients with TLE demonstrated selective impairments in recall of episodic details, relating to event, place and perceptual details, but not episodic detail relating to time or emotion in past and future events. Overall, impoverished recall of episodic event details (past and future) was related to poor relational memory. In summary, our findings are consistent with the CESH, and provide initial evidence that unilateral TLE is associated with impaired recall of past and future episodic details