scholarly journals Building memories on prior knowledge: behavioral and fMRI evidence of impairment in early Alzheimer’s Disease

2020 ◽  
Author(s):  
Pierre-Yves Jonin ◽  
Quentin Duché ◽  
Elise Bannier ◽  
Isabelle Corouge ◽  
Jean-Christophe Ferré ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Prior Knowledge ◽  
Associative Memory ◽  
Brain Regions ◽  
List Type ◽  
Healthy Controls ◽  
Experimental Knowledge ◽  
Healthy Elderly ◽  
The Right

AbstractImpaired memory is a hallmark of prodromal Alzheimer’s Disease (AD). Prior knowledge associated with the memoranda has proved to have a powerful effect on memory in healthy subjects. Yet, barely nothing is known about its effect in early AD. We used functional MRI to ask whether prior knowledge enhanced memory encoding in early AD and whether the nature of prior knowledge mattered. Early AD patients and healthy controls underwent a task-based fMRI experiment, being scanned while learning face-scene associations. Famous faces carried Pre-Experimental Knowledge (PEK) while unknown faces repeatedly familiarized prior to learning carried Experimental Knowledge (EK). As expected, PEK increased subsequent memory in healthy elderly. However, patients did not benefit from PEK. Partly non-overlapping brain networks supported PEK vs. EK encoding in healthy controls. Patients displayed impaired activation in a right subhippocampal region where activity predicted successful associative memory formation of PEK stimuli. These findings call for a thorough consideration of how prior knowledge impacts learning and suggest a possible underestimation of the extent of associative memory impairment in early AD.HighlightsLearning is impaired in prodromal AD, but we currently ignore whether prior knowledge available at encoding promotes learning in AD as it does in healthy controls.Patients with AD failed to benefit from pre-experimental prior knowledge (famous faces) by comparison with experimental knowledge (unknown but familiarized faces).fMRI responses at study revealed distinct networks underlying associative encoding for both pre-experimental and experimental knowledge.A subsequent memory effect found in control subjects for associations carrying pre-experimental knowledge in the right subhippocampal structures, including the perirhinal cortex, was absent in patients.Pre-experimental knowledge-based associative encoding relies on brain regions specifically targeted by early tau pathology.Using unfamiliar materials to probe memory in early AD might underestimate learning impairment.

scholarly journals Spatial inhibition of return is impaired in mild cognitive impairment and mild Alzheimer’s disease

2020 ◽  
Author(s):  
Xiong Jiang ◽  
James H. Howard ◽  
G. Wiliam Rebeck ◽  
R. Scott Turner
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Medial Temporal Lobe ◽  
Inhibition Of Return ◽  
Memory Performance ◽  
Brain Regions ◽  
List Type ◽  
Older Individuals

ABSTRACTSpatial inhibition of return (IOR) refers to the phenomenon by which individuals are slower to respond to stimuli appearing at a previously cued location compared to un-cued locations. Here we provide evidence supporting that spatial IOR is mildly impaired in individuals with mild cognitive impairment (MCI) or mild Alzheimer’s disease (AD), and the impairment is readily detectable using a novel double cue paradigm. Furthermore, reduced spatial IOR in high-risk healthy older individuals is associated with reduced memory and other neurocognitive task performance, suggesting that the novel double cue spatial IOR paradigm may be useful in detecting MCI and early AD.SIGNIFICANCE STATEMENTNovel double cue spatial inhibition of return (IOR) paradigm revealed a robust effect IOR deficits in individuals with mild cognitive impairment (MCI) or mild Alzheimer’s disease (AD)Spatial IOR effect correlates with memory performance in healthy older adults at a elevated risk of Alzheimer’s disease (with a family history or APOE e4 allele)The data suggests that double cue spatial IOR may be sensitive to detect early AD pathological changes, which may be linked to disease progress at the posterior brain regions (rather than the medial temporal lobe)

scholarly journals Altered neuronal gene expression in brain regions differentially affected by Alzheimer's disease: a reference data set

2008 ◽  
Vol 33 (2) ◽  
pp. 240-256 ◽  
Author(s):  
Winnie S. Liang ◽  
Travis Dunckley ◽  
Thomas G. Beach ◽  
Andrew Grover ◽  
Diego Mastroeni ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Expression Profiles ◽  
Brain Regions ◽  
Elderly Persons ◽  
Data Set ◽  
Healthy Elderly ◽  
Neuronal Gene ◽  
Laser Capture

Alzheimer's Disease (AD) is the most widespread form of dementia during the later stages of life. If improved therapeutics are not developed, the prevalence of AD will drastically increase in the coming years as the world's population ages. By identifying differences in neuronal gene expression profiles between healthy elderly persons and individuals diagnosed with AD, we may be able to better understand the molecular mechanisms that drive AD pathogenesis, including the formation of amyloid plaques and neurofibrillary tangles. In this study, we expression profiled histopathologically normal cortical neurons collected with laser capture microdissection (LCM) from six anatomically and functionally discrete postmortem brain regions in 34 AD-afflicted individuals, using Affymetrix Human Genome U133 Plus 2.0 microarrays. These regions include the entorhinal cortex, hippocampus, middle temporal gyrus, posterior cingulate cortex, superior frontal gyrus, and primary visual cortex. This study is predicated on previous parallel research on the postmortem brains of the same six regions in 14 healthy elderly individuals, for which LCM neurons were similarly processed for expression analysis. We identified significant regional differential expression in AD brains compared with control brains including expression changes of genes previously implicated in AD pathogenesis, particularly with regard to tangle and plaque formation. Pinpointing the expression of factors that may play a role in AD pathogenesis provides a foundation for future identification of new targets for improved AD therapeutics. We provide this carefully phenotyped, laser capture microdissected intraindividual brain region expression data set to the community as a public resource.

scholarly journals Elevated Angiopoietin-1 Serum Levels in Patients with Alzheimer’s Disease

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Brigitte Schreitmüller ◽  
Thomas Leyhe ◽  
Elke Stransky ◽  
Niklas Köhler ◽  
Christoph Laske
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Serum Levels ◽  
Cognitive Status ◽  
Potential Candidate ◽  
Healthy Controls ◽  
Healthy Elderly ◽  
Significant Difference ◽  
Angiopoietin 1

Background. Alzheimer's disease (AD) is the most common cause of dementia in the elderly. AD is characterized by the accumulation of amyloid plaques and neurofibrillary tangles and by massive neuronal loss in the brain. There is epidemiologic and pathologic evidence that AD is associated with vascular risk factors and vascular diseases, contributing to cerebral hypoperfusion with consecutive stimulation of angiogenesis and upregulation of proangiogenic factors such as Angiopoietin-1 (Ang-1).Methods. In the present study, we measured Ang-1 serum levels in 42 patients with AD, 20 patients with mild cognitive impairment (MCI), and in 40 healthy elderly controls by ELISA.Results. We found significantly increased Ang-1 serum levels in patients with AD compared to control subjects(P=0.003). There was no significant difference between MCI patients and healthy controls(P=0.553)or between AD and MCI patients(P=0.054). The degree of cognitive impairment as measured by the mini-mental status examination (MMSE) score was significantly correlated with the Ang-1 serum levels in all patients and healthy controls.Conclusions. We found significantly increased Ang-1 serum levels in AD patients. We could also show an association between Ang-1 serum levels and the cognitive status in all patients and healthy controls. Thus, serum Ang-1 could be a potential candidate for a biomarker panel for AD diagnosis.

scholarly journals β-Amyloid accumulation in the human brain after one night of sleep deprivation

2018 ◽  
Vol 115 (17) ◽  
pp. 4483-4488 ◽  
Author(s):  
Ehsan Shokri-Kojori ◽  
Gene-Jack Wang ◽  
Corinde E. Wiers ◽  
Sukru B. Demiral ◽  
Min Guo ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sleep Deprivation ◽  
Human Brain ◽  
Disease Risk ◽  
Apoe Genotype ◽  
Brain Regions ◽  
Night Sleep ◽  
Β Amyloid ◽  
The Right

The effects of acute sleep deprivation on β-amyloid (Aβ) clearance in the human brain have not been documented. Here we used PET and 18F-florbetaben to measure brain Aβ burden (ABB) in 20 healthy controls tested after a night of rested sleep (baseline) and after a night of sleep deprivation. We show that one night of sleep deprivation, relative to baseline, resulted in a significant increase in Aβ burden in the right hippocampus and thalamus. These increases were associated with mood worsening following sleep deprivation, but were not related to the genetic risk (APOE genotype) for Alzheimer’s disease. Additionally, baseline ABB in a range of subcortical regions and the precuneus was inversely associated with reported night sleep hours. APOE genotyping was also linked to subcortical ABB, suggesting that different Alzheimer’s disease risk factors might independently affect ABB in nearby brain regions. In summary, our findings show adverse effects of one-night sleep deprivation on brain ABB and expand on prior findings of higher Aβ accumulation with chronic less sleep.

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)

scholarly journals EEG Window Length Evaluation for the Detection of Alzheimer’s Disease over Different Brain Regions

2019 ◽  
Vol 9 (4) ◽  
pp. 81 ◽  
Author(s):  
Katerina D. Tzimourta ◽  
Nikolaos Giannakeas ◽  
Alexandros T. Tzallas ◽  
Loukas G. Astrakas ◽  
Theodora Afrantou ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Brain Regions ◽  
Spectral Features ◽  
Classification Problems ◽  
Whole Brain ◽  
Central Regions ◽  
Eeg Recordings ◽  
Cortical Regions ◽  
The Right

Alzheimer’s Disease (AD) is a neurogenerative disorder and the most common type of dementia with a rapidly increasing world prevalence. In this paper, the ability of several statistical and spectral features to detect AD from electroencephalographic (EEG) recordings is evaluated. For this purpose, clinical EEG recordings from 14 patients with AD (8 with mild AD and 6 with moderate AD) and 10 healthy, age-matched individuals are analyzed. The EEG signals are initially segmented in nonoverlapping epochs of different lengths ranging from 5 s to 12 s. Then, a group of statistical and spectral features calculated for each EEG rhythm (δ, θ, α, β, and γ) are extracted, forming the feature vector that trained and tested a Random Forests classifier. Six classification problems are addressed, including the discrimination from whole-brain dynamics and separately from specific brain regions in order to highlight any alterations of the cortical regions. The results indicated a high accuracy ranging from 88.79% to 96.78% for whole-brain classification. Also, the classification accuracy was higher at the posterior and central regions than at the frontal area and the right side of temporal lobe for all classification problems.

Brain structural and cognitive correlates of clock drawing performance in Alzheimer's disease

1999 ◽  
Vol 5 (6) ◽  
pp. 502-509 ◽  
Author(s):  
DEBORAH A. CAHN-WEINER ◽  
EDITH V. SULLIVAN ◽  
PAULA K. SHEAR ◽  
ROSEMARY FAMA ◽  
KELVIN O. LIM ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Gray Matter Volume ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Receptive Language ◽  
Semantic Knowledge ◽  
Clock Drawing Test ◽  
Clock Drawing ◽  
The Right

The Clock Drawing Test (CDT) is widely used in the assessment of dementia and is known to be sensitive to the detection of deficits in neurodegenerative disorders such as Alzheimer's disease (AD). CDT performance is dependent not only on visuospatial and constructional abilities, but also on conceptual and executive functioning; therefore, it is likely to be mediated by multiple brain regions. The purpose of the present study was to identify component cognitive processes and regional cortical volumes that contribute to CDT performance in AD. In 29 patients with probable AD, CDT performance was significantly related to right-, but not left-hemisphere, regional gray matter volume. Specifically, CDT score correlated significantly with the right anterior and posterior superior temporal lobe volumes. CDT scores showed significant relationships with tests of semantic knowledge, executive function, and visuoconstruction, and receptive language. These results suggest that in AD patients, CDT performance is attributable to impairment in multiple cognitive domains but is related specifically to regional volume loss of right temporal cortex. (JINS, 1999, 5, 502–509.)

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