ONGOING ELECTROENCEPHALOGRAPHIC RHYTHMS RELATED TO CORTICAL AROUSAL IN C57 (WILD TYPE) AND TRANSGENIC AD MOUSE MODELS

Abstract

Resting state electroencephalographic (EEG) rhythms reflect the fluctuation of cortical arousal and vigilance in a typical clinical setting, namely the EEG recording for few minutes with eyes closed (i.e., passive condition) and eyes open (i.e., active condition). Can this procedure be back-translated to C57 (wild type) and transgenic mice for physiological and pathological aging studies? For the physiological aging, EEG data were recorded from bipolar fronto-parietal electrode 25 young (4.5–6 months), 18 middle-aged (12–15 months), and 23 old (20–24 months) mice. For the pathological aging, EEG data were recorded in 23 C57 mice (20–24 months) and 22 PDAPP mice (about 20–24 months), as well as in 73 C57 mice (about 12–24 months) and 33 TASTPM mice (about 12–24 months). EEG power density was compared between short periods (about 5 minutes) of awake quiet behavior (passive condition) and dynamic exploration of the cage (active condition). Concerning the physiological aging, the passive condition showed higher EEG power at 1–2 Hz in the old group than that in the middle-age and young groups. Furthermore, the active condition exhibited a maximum EEG power at 6–8 Hz in the old group and 8–10 Hz in the young group. Concerning the pathological aging, compared to the C57 (WT) mice, PDAPP mice showed a slowing of 6–10 Hz peak in the active condition. Furthermore, compared to the C57 (WT) mice, TASTPM mice showed lower EEG power at 2–6 Hz in the passive condition and at 8–10 Hz in the active condition. The present results suggest that the on-going EEG rhythms of cortical arousal are useful to unveil neurophysiologic mechanisms of cortical neural synchronization characterizing the physiological aging in C57 (WT) mice, as well as the pathological cortical neural synchronization in transgenic (PDAPP and TASTPM) mice.