Temporal processing of past and future autobiographical events in patients with schizophrenia.

People with schizophrenia experience difficulties in remembering their past and envisioning their future. However, while alterations of event representation are well documented, little is known about how personal events are located and ordered in time. Using a think-aloud procedure, we investigated which strategies are used to determine the times of past and future events in 30 patients with schizophrenia and 30 control participants. We found that the direct access to temporal information of important events was preserved in patients with schizophrenia. However, when events were not directly located in time, patients less frequently used a combination of strategies and partly relied on different strategies to reconstruct or infer the times of past and future events. In particular, they used temporal landmark events and contextual details (e.g., about places, persons, or weather conditions) less frequently than controls to locate events in time. Furthermore, patients made more errors when they were asked to determine the temporal order of the past and future events that had been previously dated. Together, these findings shed new light on the mechanisms involved in locating and ordering personal events in past and future times and their alteration in schizophrenia.

Memories defining the self in Alzheimer's disease.

There is a debate over the extent to which personal identity or the self is preserved in patients with Alzheimer's disease (AD). Autobiographical memory deficits at early stages of AD could contribute to altering patients' self. However, the nature of the relationship between autobiographical memory deficits and the self in AD has not been much investigated experimentally. In the present study, we aimed to investigate the integrative meaning of self-defining memories (SDMs) in early stages of AD and to analyse its relationship with the self-concept. The results showed that, when compared to the control group, AD patients less frequently extracted meaning from their SDMs and the meaning was less frequently tied to the self. Patients exhibited some altered aspects of the self-concept (i.e., complexity and strength), though some other components still persisted (i.e., valence and certainty). Correlation analyses showed that the impaired integrative meaning in the AD group was correlated with some changes in self-concept. We suggest that integrative meaning may act as a bridge between autobiographical memories and the self-concept, with reduced integration abilities appearing as a potential mechanism for the deterioration of the self-concept in AD.

Envisioning the times of future events: The role of personal goals.

Episodic future thinking refers to the human capacity to imagine or simulate events that might occur in one's personal future. Previous studies have shown that personal goals guide the construction and organization of episodic future thoughts, and here we sought to investigate the role of personal goals in the process of locating imagined events in time. Using a think-aloud protocol, we found that dates were directly accessed more frequently for goal-related than goal-unrelated future events, and the goal-relevance of events was a significant predictor of direct access to temporal information on a trial-by-trial basis. Furthermore, when an event was not directly dated, references to anticipated lifetime periods were more frequently used as a strategy to determine when a goal-related event might occur. Together, these findings shed new light on the mechanisms by which personal goals contribute to the location of imagined events in future times.

Henry, where have you lost your Self?

The Self is a complex construct encompassing distinct components, including episodic and semantic autobiographical memory, the Self-concept, and the subjective sense of Self, which highest level consists of Self-awareness. The neuro-anatomical correlates are complex, and it is debated as to whether a common region could support these different components of the Self, with a particular interest for the cortical midline structures and the medial prefrontal cortex (MPFC). Alzheimer's disease (AD) constitutes an interesting model for the study of Self as autobiographical memory typically deteriorates as the disease progresses. Here, we report the unexpected case of Henry, a patient with MCI due to AD who was unable to produce any personal autobiographical memories, nor describe his Self-concept, had a poor personal semantic memory, and disclosed unusual anosognosia for this stage of the disease. His cognitive performance was compared to a group of matched AD patients and a group of healthy controls confirming that the main components of his Self were degraded. We hypothesized that it was due to a marked atrophy within the cortical midline, as visually assessed on his MRI. We further elucidated these findings through Voxel-based morphometry analysis, which confirmed a significant atrophy of the MPFC that was specific to this patient. Moreover, this revealed significant atrophy within the bilateral insular cortex. Given the stage of the disease, the degradation of the Self is unlikely to be accounted for by deficient mnemonic processes, especially as the presence of discrete temporal atrophy was noted. We suggest that this specific pattern of MPFC and insular atrophy is responsible for the systematic collapse of the patient's Self, through the breakdown of the subjective sense of Self, which is proposed as a prerequisite to all other components, according to the model proposed by Prebble, Addis, and Tippett (2013).

Reconstructing the times of past and future personal events.

Humans have the remarkable ability to mentally travel through past and future times. However, while memory for the times of past events has been much investigated, little is known about how imagined future events are temporally located. Using a think-aloud protocol, we found that the temporal location of past and future events is rarely directly accessed, but instead mostly relies on reconstructive and inferential strategies. References to lifetime periods and factual knowledge (about the self, others, and the world) were most frequently used to determine the temporal location of both past and future events. Event details (e.g., places, persons, or weather conditions) were also used, but mainly for past events. Finally, the results showed that events whose temporal location was directly accessed were judged more important for personal goals. Together, these findings shed new light on the mechanisms involved in locating personal events in past and future times.