Poster Session D, Monday, March 25, 8:00 – 10:00 am, Pacific Concourse
Damage to temporoparietal regions disrupts autobiographical memory – evidence from neurodegenerative disorders
Siddharth Ramanan1,2,3, David Foxe1,2,3, John Hodges1,3,4, Olivier Piguet1,2,3, Muireann Irish1,2,3; 1The University of Sydney, Brain and Mind Centre, Sydney, NSW, Australia, 2The University of Sydney, School of Psychology, Sydney, NSW, Australia, 3Australian Research Council Centre of Excellence in Cognition and its Disorders, NSW, Australia, 4The University of Sydney, Central Clinical School, Sydney, NSW, Australia
Autobiographical memory permits the vivid recollection of personally experienced events, and hinges on interactions between the hippocampus and frontoparietal cortices. Parietal regions, in particular, are consistently implicated in functional imaging investigations of autobiographical retrieval, yet their exact contributions remain unclear. Here, we investigated a causal role for the inferior parietal cortex in autobiographical recall, using neurodegenerative disorders as lesion models. Ten patients with Logopenic Progressive Aphasia (LPA) – a rare neurodegenerative disorder characterised by early atrophy to the left inferior parietal cortex amidst relatively spared hippocampal integrity, were contrasted with 18 Alzheimer’s disease (AD) patients, demonstrating significant hippocampal and parietal atrophy, and 16 healthy Controls. Participants completed the Autobiographical Interview - a measure examining free and probed recall of autobiographical memories from four life epochs, and underwent structural brain imaging. Relative to Controls, the LPA group displayed marked deficits in free recall of autobiographical memories across all epochs. These impairments, however, were alleviated upon provision of structured probing. The AD group, by contrast, displayed global impairments across free and probed recall, relative to Controls. Voxel-based morphometry analyses of structural MRI data implicated left inferior parietal and temporal regions in autobiographical free recall impairments in LPA. By contrast, in AD, free and probed recall performance deficits correlated with atrophy of precuneus, posterior cingulate, and prefrontal regions. Our findings suggest the importance of regions beyond the hippocampus in modulating autobiographical memory retrieval, highlighting the need to consider parietal contributions in current theoretical frameworks of autobiographical memory.
Topic Area: LONG-TERM MEMORY: Episodic