GK and Alzheimer disease: To compare the synaptic connectivity between the cortex and other brain regions, we sequentially injected the AAV2/9-mCh-gK (1.0 × 1012 vg/ml, 150 nl) and H129-dgK-G4 (5.0 × 108 pfu/ml, 150 nl) into mPFC (AP: + 1.78 mm; ML: − 0.16 mm; DV: − 3.00 mm) of 3-month-old 3 × Tg-AD or the control wildtype C57BL/6 mice at the same age (Fig. 7A).