In vivo MIE measures ISF Aβ in APP/PS1 mouse model. (A) Stereotaxic placement of MIE, reference and counter electrodes on mouse skull, with representative SWV peaks from the hippocampus of an APP/PS1 mouse and WT littermate. (B) Traces measuring human and murine Aβ with baseline subtraction are shown on the same scale to highlight the differences in peak height observed, while inset shows background level detected in the WT mouse. (C) ISF Aβ₄₀ concentrations over 180 min in APP/PS (n = 6) and WT (n = 3) mice. (D) Data in Panel C normalized to percent of baseline ISF Aβ₄₀ levels of each APP/PS1 mouse show stable levels until 118 min after MIE insertion (ANOVA post hoc analysis, P = 0.02).