Alzheimer’s disease is often described in terms of its “hardware” damage: amyloid plaques, tau pathology, neuronal loss, and progressive structural degeneration. But before the brain is visibly damaged, its activity may already be changing. In this study, we asked whether early Alzheimer-like alterations could be detected not only in brain structure, but in brain dynamics — the way neural activity moves, reorganizes, and transitions between states over time.
Using young AppNL-F/MAPT double knock-in mice, a model of early Alzheimer’s disease, we combined high-density EEG recordings with analytical tools inspired by dynamical systems and climate science. These methods allowed us to quantify the “fluidity” of brain dynamics: the ability of the brain to flexibly explore and transition between activity states. We found that, even before the appearance of amyloid plaques, Alzheimer’s model mice showed reduced brain dynamics fluidity during wakefulness. This early dynamical alteration was associated with impairments in associative memory.
We then tested whether this altered dynamics could be modulated by visual gamma entrainment using sensory stimulation (vGENUS): daily exposure to 40 Hz flickering light over two weeks. Remarkably, this non-invasive stimulation restored brain dynamics fluidity in Alzheimer’s model mice and rescued their performance in associative memory tasks. The effect built up progressively during the stimulation protocol and persisted after stimulation ended, suggesting that 40 Hz stimulation does more than transiently entrain neural activity: it may induce longer-lasting reorganization of brain function.
These findings support a “brain dynamics repair” hypothesis for 40 Hz sensory stimulation. Rather than acting only on the classical molecular hallmarks of Alzheimer’s disease, such as amyloid or tau, vGENUS may help restore the brain’s functional flexibility — in other words, repairing aspects of the brain’s “software” before irreversible “hardware” damage becomes dominant.
This work opens two complementary perspectives. First, altered brain dynamics may provide an early functional biomarker of Alzheimer’s disease, detectable before major structural pathology. Second, non-invasive rhythmic stimulation may offer a way to reshape pathological brain activity and improve cognition by restoring more flexible, healthy patterns of neural dynamics.
To know more
- Aguilera, M., Mathis, C., Herbeaux, K., Isik, A., Faranda, D., Battaglia, D., & Goutagny, R. (2025). 40 Hz light stimulation restores early brain dynamics alterations and associative memory in Alzheimer’s disease model mice. Imaging Neuroscience, 3, IMAG.a.70. https://doi.org/10.1162/imag.a.70.