FMRI contributions to addressing autobiographical memory impairment in temporal lobe pathology

Abstract

Episodic autobiographical memory (AM) allows one, through the recollection of sensory-perceptual details, thoughts and feelings, to become aware of an event as belonging to one's own past as well as being able to project into one's future. Because AM provides a sense of self-continuity, contributes to the integrity of the self, and helps predicting future experiences, any deficit of AM may have debilitating consequences for everyday life functioning. Understanding AM failure and the underlying neural mechanisms has the potential to shed light on brain reorganization mechanisms and engagement of compensatory processes. Functional magnetic resonance imaging (fMRI) provides the most promising imaging method to tackle these issues. We reviewed evidence from the few studies that used fMRI to investigate the functionality of the residual tissue, the neural reorganization and compensatory mechanisms in patients with neurological conditions due to impaired medial temporal lobe. Overall, these studies highlight the importance of the left hippocampus, which when atrophied and not functional leads to AM deficits but its residual functionality may support relatively normal AM recollection. When damaged hippocampal tissue is not functional, other brain regions (e.g. , the medial prefrontal cortex) may be involved to compensate impairment, but they appear generally ineffective to support detailed episodic recollection.© 2014 Baishideng Publishing Group Co., Limited. All rights reserved.Key words: Functional magnetic resonance imaging; Autobiographical memory; Amnesia; Medial temporal lobe; Memory deficit; Reorganization Core tip: Functional magnetic resonance imaging investigations of patients with impaired autobiographical memory (AM) can greatly contribute to further our understanding of brain reorganization mechanisms and engagement of compensatory processes after damage to the medial temporal lobe. These investigations are reviewed here. Overall, they highlight the importance of the left hippocampus, which when atrophied and not functional leads to deficits in AM but its residual functionality may support relatively normal AM recollection. When damaged hippocampal tissue is not functional, other brain regions (e.g. , the medial prefrontal cortex) may be involved to compensate impairment, but they appear generally ineffective to support detailed recollection.Denkova EJ, Manning L. FMRI contributions to addressing autobiographical memory impairment in temporal lobe pathology.

Memory Dysfunction

“…9 Functional neuroimaging data suggest that the left medial temporal lobe may be more active in the recall of autobiographic memories, although adult patients with known medial temporal lobe pathology demonstrate compensatory increased activation in the ventral prefrontal cortex, precuneus, and lingual gyrus. 10 Conversely, correlation of right hippocampal function with visual memory has been demonstrated in patients with varying degrees of memory deficit due to mild cognitive impairment and Alzheimer disease. 11 Additionally, the right posterior hippocampal gray matter volume of London taxi drivers, whose job requires complex visual memory function, increases with the number of years of taxi driving and greater navigational expertise.…”

Why are places so special? Uncovering how our brain reacts to meaningful places

“…Autobiographical memory research has examined neurological responses to events and places belonging to people's own past (Denkova & Manning, 2014). Distinct neurological patterns have been found when scanned respondents view images of places they have visited themselves in comparison to images of places visited by others (Rissman, Chow, Reggente & Wagner, 2016).…”