Auditory steady-state responses in the auditory cortex of mice during estrus cycle

Auditory-steady state responses (ASSRs) disclose the brain's potency to oscillate and have been suggested to serve as biomarkers in various psychiatric disorders. GABAergic neurotransmission, a critical component of brain oscillations, is strongly influenced by sex hormones. In line, the severity of symptoms in psychiatric disorders has been linked to changes in sex hormones during the menstrual cycle. However, how these sex hormones affect ASSRs remain largely unknown. This was addressed by performing chronic recordings of ASSRs in mice while monitoring its estrus cycle. Here, the stability of ASSRs during long-term recordings was validated and showed good reliability. 40 Hz ASSRs showed changes throughout the estrus cycle where it decreased in the metestrus phase compared to the diestrus phase. In contrast, other frequency ASSRs did not show significant changes throughout the estrus cycle. Taken together, our findings illustrate that the estrus cycle may influence the generation of ASSRs and that the phase of the estrus cycle should be taken into consideration when ASSRs are recorded in females.