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Autobiographical memory in semantic dementia: a longitudinal fMRI study.

Maguire EA, Kumaran D, Hassabis D, Kopelman MD - Neuropsychologia (2010)

Bottom Line: There was no evidence of a temporal gradient.This was subsequently augmented by up-regulation of other parts of the memory system, namely ventromedial and ventrolateral prefrontal cortex, right lateral temporal cortex, and precuneus.Our findings inform theoretical debates about the role of the hippocampus and neocortical areas in supporting remote autobiographical memories.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK. e.maguire@fil.ion.ucl.ac.uk

ABSTRACT
Whilst patients with semantic dementia (SD) are known to suffer from semantic memory and language impairments, there is less agreement about whether memory for personal everyday experiences, autobiographical memory, is compromised. In healthy individuals, functional MRI (fMRI) has helped to delineate a consistent and distributed brain network associated with autobiographical recollection. Here we examined how the progression of SD affected the brain's autobiographical memory network over time. We did this by testing autobiographical memory recall in a SD patient, AM, with fMRI on three occasions, each one year apart, during the course of his disease. At the outset, his autobiographical memory was intact. This was followed by a gradual loss in recollective quality that collapsed only late in the course of the disease. There was no evidence of a temporal gradient. Initially, AM's recollection was supported by the classic autobiographical memory network, including atrophied tissue in hippocampus and temporal neocortex. This was subsequently augmented by up-regulation of other parts of the memory system, namely ventromedial and ventrolateral prefrontal cortex, right lateral temporal cortex, and precuneus. A final step-change in the areas engaged and the quality of recollection then preceded the collapse of autobiographical memory. Our findings inform theoretical debates about the role of the hippocampus and neocortical areas in supporting remote autobiographical memories. Furthermore, our results suggest it may be possible to define specific stages in SD-related memory decline, and that fMRI could complement MRI and neuropsychological measures in providing more precise prognostic and rehabilitative information for clinicians and carers.

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Related in: MedlinePlus

Structural MRI brain scans of the patient. Top panels show coronal sections through the brain of patient AM at the level of the mid-temporal lobe for each year. Running vertically below each year's coronal section are further axial and coronal sections from that year's MRI scan superimposed on which are the results of the VBM analysis for that year. The pronounced atrophy of cortical and medial left temporal regions is apparent at year 1. Scans from the subsequent years show a progression in this atrophy, and additional pathology starting in homologous areas on the right. See main text, and Table S1 (in Supplementary Materials) for full details of the VBM findings.
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fig1: Structural MRI brain scans of the patient. Top panels show coronal sections through the brain of patient AM at the level of the mid-temporal lobe for each year. Running vertically below each year's coronal section are further axial and coronal sections from that year's MRI scan superimposed on which are the results of the VBM analysis for that year. The pronounced atrophy of cortical and medial left temporal regions is apparent at year 1. Scans from the subsequent years show a progression in this atrophy, and additional pathology starting in homologous areas on the right. See main text, and Table S1 (in Supplementary Materials) for full details of the VBM findings.

Mentions: Fig. 1 shows the progressive change in AM's structural MRI brain scans during the study. In order to formally assess the extent of atrophy in patient AM across the whole brain, we compared the structural MRI scans of AM with those of the group of 10 control participants using voxel-based morphometry (VBM; Ashburner & Friston, 2005; see also Section 2.5). This revealed that at year 1, AM had significantly less grey matter volume in the left hippocampus and left anterior-lateral temporal lobe. There were no grey matter differences anywhere else in the brain. By year 2, the atrophy had spread and was starting to involve the right anterior temporal cortex, the right temporal pole, right anterior hippocampus, and right cerebellum. By year 3, there was very significant atrophy of both temporal lobes, including the hippocampi, still more extensive on the left, and also the right cerebellum, with no other significant grey matter differences evident elsewhere in the brain. See Table S1 (Supplementary Materials) for full details of the VBM findings.


Autobiographical memory in semantic dementia: a longitudinal fMRI study.

Maguire EA, Kumaran D, Hassabis D, Kopelman MD - Neuropsychologia (2010)

Structural MRI brain scans of the patient. Top panels show coronal sections through the brain of patient AM at the level of the mid-temporal lobe for each year. Running vertically below each year's coronal section are further axial and coronal sections from that year's MRI scan superimposed on which are the results of the VBM analysis for that year. The pronounced atrophy of cortical and medial left temporal regions is apparent at year 1. Scans from the subsequent years show a progression in this atrophy, and additional pathology starting in homologous areas on the right. See main text, and Table S1 (in Supplementary Materials) for full details of the VBM findings.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2806951&req=5

fig1: Structural MRI brain scans of the patient. Top panels show coronal sections through the brain of patient AM at the level of the mid-temporal lobe for each year. Running vertically below each year's coronal section are further axial and coronal sections from that year's MRI scan superimposed on which are the results of the VBM analysis for that year. The pronounced atrophy of cortical and medial left temporal regions is apparent at year 1. Scans from the subsequent years show a progression in this atrophy, and additional pathology starting in homologous areas on the right. See main text, and Table S1 (in Supplementary Materials) for full details of the VBM findings.
Mentions: Fig. 1 shows the progressive change in AM's structural MRI brain scans during the study. In order to formally assess the extent of atrophy in patient AM across the whole brain, we compared the structural MRI scans of AM with those of the group of 10 control participants using voxel-based morphometry (VBM; Ashburner & Friston, 2005; see also Section 2.5). This revealed that at year 1, AM had significantly less grey matter volume in the left hippocampus and left anterior-lateral temporal lobe. There were no grey matter differences anywhere else in the brain. By year 2, the atrophy had spread and was starting to involve the right anterior temporal cortex, the right temporal pole, right anterior hippocampus, and right cerebellum. By year 3, there was very significant atrophy of both temporal lobes, including the hippocampi, still more extensive on the left, and also the right cerebellum, with no other significant grey matter differences evident elsewhere in the brain. See Table S1 (Supplementary Materials) for full details of the VBM findings.

Bottom Line: There was no evidence of a temporal gradient.This was subsequently augmented by up-regulation of other parts of the memory system, namely ventromedial and ventrolateral prefrontal cortex, right lateral temporal cortex, and precuneus.Our findings inform theoretical debates about the role of the hippocampus and neocortical areas in supporting remote autobiographical memories.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK. e.maguire@fil.ion.ucl.ac.uk

ABSTRACT
Whilst patients with semantic dementia (SD) are known to suffer from semantic memory and language impairments, there is less agreement about whether memory for personal everyday experiences, autobiographical memory, is compromised. In healthy individuals, functional MRI (fMRI) has helped to delineate a consistent and distributed brain network associated with autobiographical recollection. Here we examined how the progression of SD affected the brain's autobiographical memory network over time. We did this by testing autobiographical memory recall in a SD patient, AM, with fMRI on three occasions, each one year apart, during the course of his disease. At the outset, his autobiographical memory was intact. This was followed by a gradual loss in recollective quality that collapsed only late in the course of the disease. There was no evidence of a temporal gradient. Initially, AM's recollection was supported by the classic autobiographical memory network, including atrophied tissue in hippocampus and temporal neocortex. This was subsequently augmented by up-regulation of other parts of the memory system, namely ventromedial and ventrolateral prefrontal cortex, right lateral temporal cortex, and precuneus. A final step-change in the areas engaged and the quality of recollection then preceded the collapse of autobiographical memory. Our findings inform theoretical debates about the role of the hippocampus and neocortical areas in supporting remote autobiographical memories. Furthermore, our results suggest it may be possible to define specific stages in SD-related memory decline, and that fMRI could complement MRI and neuropsychological measures in providing more precise prognostic and rehabilitative information for clinicians and carers.

Show MeSH
Related in: MedlinePlus