Audiovisual gamma stimulation enhances hippocampal neurogenesis and neural circuit plasticity in aging mice.

Gamma oscillations are disrupted in various neurological disorders, including Alzheimer's disease (AD). In AD mouse models, non-invasive audiovisual stimulation (AuViS) at 40 Hz enhances gamma oscillations, clears amyloid-beta, and improves cognition. We investigated mechanisms of circuit remodeling underlying these restorative effects by leveraging the sensitivity of hippocampal neurogenesis to activity in middle-aged wild-type mice. AuViS increased progenitor cell proliferation, neuronal differentiation and morphological maturation of newborn granule cells, promoting their synaptic integration. While visual or auditory stimuli alone induced dendritic growth, axonal changes required combined audiovisual stimulation. The actions of AuViS involved neurotrophin pathways, as shown by the lack of effect upon TrkB signaling blockade. These results reveal widespread plasticity mechanisms triggered by AuViS, a therapeutic approach currently proposed for treating neurological disorders in humans.