Atrophy, hypometabolism and white matter abnormalities in semantic dementia tell a coherent story.

@article{AcostaCabronero2011AtrophyHA,
  title={Atrophy, hypometabolism and white matter abnormalities in semantic dementia tell a coherent story.},
  author={Julio Acosta-Cabronero and Karalyn E Patterson and Tim D. Fryer and John R. Hodges and George Pengas and Guy B. Williams and Peter J. Nestor},
  journal={Brain : a journal of neurology},
  year={2011},
  volume={134 Pt 7},
  pages={
          2025-35
        }
}
Semantic dementia, in which there is progressive deterioration of semantic knowledge, is associated with focal, typically asymmetric, temporal lobe degeneration. The ventrorostral temporal lobe is most severely affected and there is concordance between atrophy and reduced metabolic activity. In this study, we confirmed the veracity of this claim using ¹⁸F-fluorodeoxyglucose positron emission tomography and anatomical magnetic resonance images. The principal aim, however, was to understand the… 

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References

SHOWING 1-10 OF 52 REFERENCES
Language networks in semantic dementia.
TLDR
This study shows that semantic dementia is associated with anatomical damage to the major superior and inferior temporal white matter connections of the left hemisphere likely involved in semantic and lexical processes, with relative sparing of the fronto-parietal superior longitudinal fasciculus.
What the left and right anterior fusiform gyri tell us about semantic memory.
TLDR
The best, indeed the only, strong predictor of semantic scores across a set of 21 patients with frontotemporal lobar degeneration with semantic impairment was degree of hypometabolism in the anterior fusiform region subjacent to the head and body of the hippocampus.
Differing patterns of temporal atrophy in Alzheimer’s disease and semantic dementia
TLDR
Hippocampal atrophy is not specific for AD but is also seen in semantic dementia, and these findings have implications for diagnosis and understanding of the cognitive deficits in AD and semantic dementia.
Declarative memory impairments in Alzheimer's disease and semantic dementia
Patterns of temporal lobe atrophy in semantic dementia and Alzheimer's disease
TLDR
There is a marked difference in the distribution of temporal lobe atrophy in semantic dementia and Alzheimer's disease, which suggests that semantic memory is subserved by anterior temporal lobe structures, within which the middle and inferior temporal gyri may play a key role.
The ventral and inferolateral aspects of the anterior temporal lobe are crucial in semantic memory: evidence from a novel direct comparison of distortion-corrected fMRI, rTMS, and semantic dementia.
TLDR
By utilizing the same semantic task across semantic dementia, rTMS, and distortion-corrected fMRI in normal participants, the results were highly convergent and indicated that crucial regions within the ATL for semantic representation include the anterior inferior temporal gyrus, anterior fusiform gyrus and the anterior superior temporal sulcus.
Atrophy patterns in histologic vs clinical groupings of frontotemporal lobar degeneration
TLDR
There is predictable atrophy for clinical variants of frontotemporal dementia (FTD), histologic FTD variants show no noticeable differences, and reports of specific atrophy profiles are likely the result of idiosyncrasies in small groups.
Non-invasive mapping of connections between human thalamus and cortex using diffusion imaging
TLDR
The results provide the first quantitative demonstration of reliable inference of anatomical connectivity between human gray matter structures using diffusion data and the first connectivity-based segmentation of gray matter.
...
...