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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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The brain networks associated with autobiographical memory retrieval in patient AM. Brain areas more active during autobiographical memory retrieval compared with the control task are shown for each year. Functional images are shown on a selection of relevant axial, sagittal and coronal sections from the patient's structural MRI scan contemporaneous with the functional images for that year. See Table 4 for full details of activation locations. Activations are shown at a threshold of p < 0.005 uncorrected. L: left side of the brain.
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fig4: The brain networks associated with autobiographical memory retrieval in patient AM. Brain areas more active during autobiographical memory retrieval compared with the control task are shown for each year. Functional images are shown on a selection of relevant axial, sagittal and coronal sections from the patient's structural MRI scan contemporaneous with the functional images for that year. See Table 4 for full details of activation locations. Activations are shown at a threshold of p < 0.005 uncorrected. L: left side of the brain.

Mentions: We first ascertained the brain areas that were active during the recall of autobiographical events compared with the low level control task for each year AM was tested. Full details of the results are reported in Fig. 4 and Table 4. To summarise, at year 1 and year 2 the ‘classic’ autobiographical brain network was activated including medial prefrontal cortex, anterior and lateral temporal cortex, medial temporal areas including hippocampus, retrosplenial cortex, and medial parietal areas. As with the control participant, because the stimuli in the control task lacked any discernible objects/features, there was also increased activation in posterior temporal and occipital areas for the autobiographical memory photographs. Given the extent of his left temporal neocortical atrophy it is interesting to note that the residual tissue was still active. This was also true at year 1 for both hippocampi, and the right hippocampus at year 2.


Autobiographical memory in semantic dementia: a longitudinal fMRI study.

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

The brain networks associated with autobiographical memory retrieval in patient AM. Brain areas more active during autobiographical memory retrieval compared with the control task are shown for each year. Functional images are shown on a selection of relevant axial, sagittal and coronal sections from the patient's structural MRI scan contemporaneous with the functional images for that year. See Table 4 for full details of activation locations. Activations are shown at a threshold of p < 0.005 uncorrected. L: left side of the brain.
© Copyright Policy
Related In: Results  -  Collection

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

fig4: The brain networks associated with autobiographical memory retrieval in patient AM. Brain areas more active during autobiographical memory retrieval compared with the control task are shown for each year. Functional images are shown on a selection of relevant axial, sagittal and coronal sections from the patient's structural MRI scan contemporaneous with the functional images for that year. See Table 4 for full details of activation locations. Activations are shown at a threshold of p < 0.005 uncorrected. L: left side of the brain.
Mentions: We first ascertained the brain areas that were active during the recall of autobiographical events compared with the low level control task for each year AM was tested. Full details of the results are reported in Fig. 4 and Table 4. To summarise, at year 1 and year 2 the ‘classic’ autobiographical brain network was activated including medial prefrontal cortex, anterior and lateral temporal cortex, medial temporal areas including hippocampus, retrosplenial cortex, and medial parietal areas. As with the control participant, because the stimuli in the control task lacked any discernible objects/features, there was also increased activation in posterior temporal and occipital areas for the autobiographical memory photographs. Given the extent of his left temporal neocortical atrophy it is interesting to note that the residual tissue was still active. This was also true at year 1 for both hippocampi, and the right hippocampus at year 2.

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