scholarly journals Patterns of Regional Brain Hypometabolism Associated with Knowledge of Semantic Features and Categories in Alzheimer's Disease

2006 ◽  
Vol 18 (12) ◽  
pp. 2138-2151 ◽  
Author(s):  
Roland Zahn ◽  
Peter Garrard ◽  
Jochen Talazko ◽  
Matthias Gondan ◽  
Philine Bubrowski ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Semantic Memory ◽  
Functional Properties ◽  
Functional Property ◽  
Semantic Knowledge ◽  
Brain Areas ◽  
Functional Features ◽  
Property Verification ◽  
Living Objects

The study of semantic memory in patients with Alzheimer's disease (AD) has raised important questions about the representation of conceptual knowledge in the human brain. It is still unknown whether semantic memory impairments are caused by localized damage to specialized regions or by diffuse damage to distributed representations within nonspecialized brain areas. To our knowledge, there have been no direct correlations of neuroimaging of in vivo brain function in AD with performance on tasks differentially addressing visual and functional knowledge of living and nonliving concepts. We used a semantic verification task and resting 18-fluorodeoxyglucose positron emission tomography in a group of mild to moderate AD patients to investigate this issue. The four task conditions required semantic knowledge of (1) visual, (2) functional properties of living objects, and (3) visual or (4) functional properties of nonliving objects. Visual property verification of living objects was significantly correlated with left posterior fusiform gyrus metabolism (Brodmann's area [BA] 37/19). Effects of visual and functional property verification for non-living objects largely overlapped in the left anterior temporal (BA 38/20) and bilateral premotor areas (BA 6), with the visual condition extending more into left lateral precentral areas. There were no associations with functional property verification for living concepts. Our results provide strong support for anatomically separable representations of living and nonliving concepts, as well as visual feature knowledge of living objects, and against distributed accounts of semantic memory that view visual and functional features of living and nonliving objects as distributed across a common set of brain areas.

Semantic memory and depressive symptoms in patients with subjective cognitive decline, mild cognitive impairment, and Alzheimer's disease

2017 ◽  
Vol 29 (7) ◽  
pp. 1123-1135 ◽  
Author(s):  
J. Lehrner ◽  
G. Coutinho ◽  
P. Mattos ◽  
D. Moser ◽  
M. Pflüger ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Depressive Symptoms ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Semantic Memory ◽  
Semantic Knowledge ◽  
Subjective Cognitive Decline ◽  
Healthy Controls

ABSTRACTBackground:Semantic memory may be impaired in clinically recognized states of cognitive impairment. We investigated the relationship between semantic memory and depressive symptoms (DS) in patients with cognitive impairment.Methods:323 cognitively healthy controls and 848 patients with subjective cognitive decline (SCD), mild cognitive impairment (MCI), and Alzheimer's disease (AD) dementia were included. Semantic knowledge for famous faces, world capitals, and word vocabulary was investigated.Results:Compared to healthy controls, we found a statistically significant difference of semantic knowledge in the MCI groups and the AD group, respectively. Results of the SCD group were mixed. However, two of the three semantic memory measures (world capitals and word vocabulary) showed a significant association with DS.Conclusions:We found a difference in semantic memory performance in MCI and AD as well as an association with DS. Results suggest that the difference in semantic memory is due to a storage loss rather than to a retrieval problem.

Semantic memory in Alzheimer's disease: Loss of knowledge or deficits in retrieval? Introduction from the symposium organizer

1999 ◽  
Vol 5 (7) ◽  
pp. 623-625 ◽  
Author(s):  
BETH A. OBER
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Semantic Memory ◽  
Research Society ◽  
Semantic Knowledge ◽  
The Other ◽  
Memory Disorders ◽  
Concerted Effort

This is the fifth symposium to appear in the Journal of the International Neuropsychological Society (JINS). This symposium was developed in tandem with a Memory Disorders Research Society conference symposium on semantic memory in probable Alzheimer's disease (AD); the conference was held in Boston in October, 1998. Three of the conference presenters agreed to submit papers based on their talks to this JINS symposium. A concerted effort was made to solicit additional papers from researchers who have consistently weighed in on either the storage-loss or retrieval-difficulty side of the debate regarding semantic memory in AD, and from researchers who have obtained some evidence consistent with one view as well as some evidence consistent with the other view. In the end, not only was the theoretical continuum fairly well represented, but the methodological continuum, with regard to the types of tasks used and the degree to which the tasks required implicit versus explicit utilization of semantic knowledge, was also well covered.

scholarly journals Do Alzheimer’s Disease Patients Benefit From Prior-Knowledge in Associative Recognition Memory?

2019 ◽  
Vol 25 (04) ◽  
pp. 443-452
Author(s):  
Emma Delhaye ◽  
Adrien Folville ◽  
Isabelle Simoes Loureiro ◽  
Laurent Lefebvre ◽  
Eric Salmon ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Older Adults ◽  
Alzheimer's Disease ◽  
Prior Knowledge ◽  
Semantic Memory ◽  
Associative Memory ◽  
Healthy Aging ◽  
Memory Task ◽  
Semantic Knowledge ◽  
Healthy Older Adults

AbstractObjectives: Although the influence of prior knowledge on associative memory in healthy aging has received great attention, it has never been studied in Alzheimer’s disease (AD). This study aimed at assessing whether AD patients could benefit from prior knowledge in associative memory and whether such benefit would be related to the integrity of their semantic memory. Methods: Twenty-one AD patients and 21 healthy older adults took part in an associative memory task using semantically related and unrelated word pairs and were also submitted to an evaluation of their semantic memory. Results: While participants of both groups benefited from semantic relatedness in associative discrimination, related pairs recognition was significantly predicted by semantic memory integrity in healthy older adults only. Conclusions: We suggest that patients benefitted from semantic knowledge to improve their performance in the associative memory task, but that such performance is not related to semantic knowledge integrity evaluation measures because the two tasks differ in the way semantic information is accessed: in an automatic manner for the associative memory task, with automatic processes thought to be relatively preserved in AD, and in a controlled manner for the semantic knowledge evaluation, with controlled processes thought to be impaired in AD. (JINS, 2019, 25, 443–452)

Alzheimer's Disease Brain Areas: The Machine Learning Support for Blind Localization

2016 ◽  
Vol 13 (5) ◽  
pp. 498-508 ◽  
Author(s):  
V. Vigneron ◽  
A. Kodewitz ◽  
A. M. Tome ◽  
S. Lelandais ◽  
E. Lang
Keyword(s):  
Machine Learning ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Learning Support ◽  
Brain Areas

Neuropeptides in Alzheimer’s Disease: An Update

2019 ◽  
Vol 16 (6) ◽  
pp. 544-558 ◽  
Author(s):  
Carla Petrella ◽  
Maria Grazia Di Certo ◽  
Christian Barbato ◽  
Francesca Gabanella ◽  
Massimo Ralli ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Animal Models ◽  
Potential Role ◽  
Brain Distribution ◽  
Brain Areas ◽  
Small Proteins ◽  
Current Review ◽  
The Central Nervous System ◽  
Available Information

Neuropeptides are small proteins broadly expressed throughout the central nervous system, which act as neurotransmitters, neuromodulators and neuroregulators. Growing evidence has demonstrated the involvement of many neuropeptides in both neurophysiological functions and neuropathological conditions, among which is Alzheimer’s disease (AD). The role exerted by neuropeptides in AD is endorsed by the evidence that they are mainly neuroprotective and widely distributed in brain areas responsible for learning and memory processes. Confirming this point, it has been demonstrated that numerous neuropeptide-containing neurons are pathologically altered in brain areas of both AD patients and AD animal models. Furthermore, the levels of various neuropeptides have been found altered in both Cerebrospinal Fluid (CSF) and blood of AD patients, getting insights into their potential role in the pathophysiology of AD and offering the possibility to identify novel additional biomarkers for this pathology. We summarized the available information about brain distribution, neuroprotective and cognitive functions of some neuropeptides involved in AD. The main focus of the current review was directed towards the description of clinical data reporting alterations in neuropeptides content in both AD patients and AD pre-clinical animal models. In particular, we explored the involvement in the AD of Thyrotropin-Releasing Hormone (TRH), Cocaine- and Amphetamine-Regulated Transcript (CART), Cholecystokinin (CCK), bradykinin and chromogranin/secretogranin family, discussing their potential role as a biomarker or therapeutic target, leaving the dissertation of other neuropeptides to previous reviews.

scholarly journals Anhedonia in Semantic Dementia—Exploring Right Hemispheric Contributions to the Loss of Pleasure

2021 ◽  
Vol 11 (8) ◽  
pp. 998
Author(s):  
Siobhán R. Shaw ◽  
Hashim El-Omar ◽  
Siddharth Ramanan ◽  
Olivier Piguet ◽  
Rebekah M. Ahmed ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Temporal Lobe ◽  
Rating Scale ◽  
Right Hemisphere ◽  
Semantic Knowledge ◽  
Semantic Dementia ◽  
Anterior Cingulate ◽  
Functional Impairments ◽  
Lobe Atrophy

Semantic dementia (SD) is a younger-onset neurodegenerative disease characterised by progressive deterioration of the semantic knowledge base in the context of predominantly left-lateralised anterior temporal lobe (ATL) atrophy. Mounting evidence indicates the emergence of florid socioemotional changes in SD as atrophy encroaches into right temporal regions. How lateralisation of temporal lobe pathology impacts the hedonic experience in SD remains largely unknown yet has important implications for understanding socioemotional and functional impairments in this syndrome. Here, we explored how lateralisation of temporal lobe atrophy impacts anhedonia severity on the Snaith–Hamilton Pleasure Scale in 28 SD patients presenting with variable right- (SD-R) and left-predominant (SD-L) profiles of temporal lobe atrophy compared to that of 30 participants with Alzheimer’s disease and 30 healthy older Control participants. Relative to Controls, SD-R but not SD-L or Alzheimer’s patients showed clinically significant anhedonia, representing a clear departure from premorbid levels. Overall, anhedonia was more strongly associated with functional impairment on the Frontotemporal Dementia Functional Rating Scale and motivational changes on the Cambridge Behavioural Inventory in SD than in Alzheimer’s disease patients. Voxel-based morphometry analyses revealed that anhedonia severity correlated with reduced grey matter intensity in a restricted set of regions centred on right orbitofrontal and temporopolar cortices, bilateral posterior temporal cortices, as well as the anterior cingulate gyrus and parahippocampal gyrus, bilaterally. Finally, regression and mediation analysis indicated a unique role for right temporal lobe structures in modulating anhedonia in SD. Our findings suggest that degeneration of predominantly right-hemisphere structures deleteriously impacts the capacity to experience pleasure in SD. These findings offer important insights into hemispheric lateralisation of motivational disturbances in dementia and suggest that anhedonia may emerge at different timescales in the SD disease trajectory depending on the integrity of the right hemisphere.

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