Anesthesia-induced hippocampal-cortical hyperactivity and tau hyperphosphorylation impair remote memory retrieval in Alzheimer's disease

INTRODUCTION: Anesthesia often exacerbates memory recall difficulties in individuals with Alzheimer's disease (AD), but the underlying mechanisms remain unclear.METHODS: We used in vivo Ca2+ imaging, viral-based circuit tracing, and chemogenetic approaches to investigate anesthesia-induced remote memory impairment in mouse models of presymptomatic AD.RESULTS: Our study identified pyramidal neuron hyperactivity in the anterior cingulate cortex (ACC) as a significant contributor to anesthesia-induced remote memory impairment. This ACC hyperactivation arises from the disinhibition of local inhibitory circuits and increased excitatory inputs from the hippocampal CA1 region. Inhibiting hyperactivity in the CA1-ACC circuit improved memory recall after anesthesia. Moreover, anesthesia led to increased tau phosphorylation in the hippocampus, and inhibiting this hyperphosphorylation prevented ACC hyperactivity and subsequent memory impairment.DISCUSSION: Hippocampal-cortical hyperactivity plays a role in anesthesia-induced remote memory impairment. Targeting tau hyperphosphorylation shows promise as a therapeutic strategy to mitigate anesthesia-induced neural network dysfunction and retrograde amnesia in AD.