Abstract
Functional network activity alterations are one of the earliest hallmarks of Alzheimer’s disease (AD), detected prior to amyloidosis and tauopathy. Better understanding the neuronal underpinnings of such network alterations could offer mechanistic insight into AD progression. Here, we examined a mouse model (early-tauopathy 3xTgAD mice) recapitulating this early AD stage. We found resting functional connectivity loss within ventral networks, including the entorhinal cortex, aligning with the spatial distribution of tauopathy reported in humans. Unexpectedly, in contrast to decreased connectivity at rest, 3xTgAD mice show enhanced fMRI signal within several projection areas following optogenetic activation of the entorhinal cortex. We corroborate this finding by demonstrating neuronal facilitation within ventral networks and synaptic hyperexcitability in projection targets. 3xTgAD mice thus reveal a dichotomic hypo-connected resting/hyper-responsive active phenotype. The strong homotopy between the areas affected supports the translatability of this pathophysiological model to tau-related deficits in humans.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
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List of abbreviations
- AAV
- adeno-associated virus
- ACB
- nucleus accumbens
- AD
- Alzheimer’s disease
- BLA
- baso-lateral amygdala
- BOLD
- blood-oxygen-level-dependent
- DG
- dentate gyrus
- DMN
- default-mode network
- ENTl
- lateral entorhinal cortex
- ILA
- infralimbic area
- mPFC
- medial prefrontal cortex
- ofMRI
- optogenetics functional MRI
- ReHo
- regional homogeneity
- rsfMRI
- resting state functional MRI