IC‐P1‐059: Activation of dorsolateral prefrontal cortex during rest in early Alzheimer's disease: A preliminary study using 4 Tesla fMRI
Bibliographic record
Abstract
Functional MRI studies on Alzheimer's disease (AD) often examine task-related activation, for which images taken during one cognitive state are compared with those during a reference state. When the resting state serves as this reference, inter-group differences in fMRI activation patterns thus may result from differences between the groups in baseline neural activity. We examined fluctuations of fMRI activation at rest in mild AD patients and in cognitively intact older adults. We began with a focus on the dorsolateral prefrontal cortex (DLPFC) as a region of interest because of its role in executive functions and working memory, and because of its frequent involvement in fMRI studies of cognitive tasks. Four patients with mild AD and eight healthy older adults were scanned on a 4-Tesla Varian-Oxford human imaging system. The subjects were instructed to remain relaxed while focusing their eyes on a central fixation for over 60 seconds. Functional images were acquired using two-shot spiral readout; 22 axial slices of 5.5+0.5mm. Data were processed using independent component analysis and artifacts attributed to physical and physiological sources were filtered. The time course of the representative resting state components (ICs) that were common across AD and healthy subjects were identified and analyzed applying GLM (p=0.001, uncorrected, extent=6). Signal changes, measured as the percentage difference between the highest and lowest of three consecutive fMRI data points during a scan were calculated. The fMRI signals filtered for known imaging signal to noise ratio and physiological variations fluctuated during the resting phase. Three ICs were identified across subjects with each being characterized as a low frequency response (<0.08Hz). Within the DFPLC, both the mean percentage change of the signal and the statistics in the contrast maps (i.e., for an IC) were greater in AD patients than in cognitively healthy older subjects. Regular patterns of fluctuations in fMRI indices of neural activity exist during rest and patients with mild AD demonstrated increased resting-state DLPFC activity. These resting state differences may reflect an early neurocompensatory response to AD.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".