Gamma amplitude modulation by theta phase is impaired in APP23 mice. (A) Raw EEG (LFP), band pass filtered signals for theta (4-12 Hz) and gamma (25-100 Hz) oscillations, gamma amplitude envelope (green) and theta phase in APP23 and non-transgenic (non-tg) mice. Representative signals from 5 animals per genotype are shown. (B) Representative phase-amplitude comodulograms computed for hippocampal LFPs recorded in non-transgenic (non-tg) and APP23 mice. (C) Phase-amplitude plot computed for hippocampal LFPs recorded in non-transgenic (non-tg) and APP23 mice. (n = 5) means ± s.e.m. (D) Modulation index computed for the phase-amplitude distributions shown in C. (n = 5) means ± s.e.m. *p < 0.05 (Student’s t-test).