| Abstract [eng] |
Recent studies suggest that the natural fluctuations in female sex hormones throughout the menstrual cycle may influence brain activity, executive functions, emotional regulation, and response inhibition. Unfortunately, many EEG studies have assessed isolated resting-state or task-response measures and have been limited to comparing a few phases of the menstrual cycle or to imprecise tracking of menstrual phases. The aim of this pilot study is to assess the dynamics of brain activity throughout the female menstrual cycle using electroencephalography. The study included six women who did not experience premenstrual symptoms, were not using hormonal contraception, and had regular menstrual cycles, as well as one woman with severe premenstrual symptoms who was using hormonal contraception. Repeated measurements were taken during six phases of the menstrual cycle (early and late follicular, ovulation, and early, mid, and late luteal phases). During the study, resting-state EEG was recorded (to assess aperiodic spectral slope, alpha power, and individual alpha frequency parameters), a Go/No-Go task was performed (to assess Go and No-Go accuracy and reaction time), and event-related potentials (ERP) (to assess N2 and P3 latencies and amplitudes) and psychological questionnaires (the Well-Being Questionnaire - WBQ and the BIS-11 impulsivity scale). In the group of women who did not experience premenstrual symptoms, resting-state EEG parameters (aperiodic slope, alpha power, and individual alpha frequency) showed individual variability and did not differ significantly across menstrual cycle phases. Only eye state showed a statistically significant difference: the open-eye state was characterized not only by lower alpha power and higher IAF, but also by a lower spectral slope than the closed-eye state. Analysis of the Go/No-Go task revealed that reaction time was significantly shorter in the late follicular and mid-luteal phases, although response accuracy and response inhibition remained stable throughout the menstrual cycle. ERP analysis of the Go/No-Go task showed that in the late luteal phase, shorter N2 latency was observed in the No-Go condition, while other evaluated ERP parameters (N2 No-Go amplitude, N2 Go and P3 No-Go latency and amplitude) did not differ significantly across menstrual cycle phases. An analysis of the relationships between the parameters revealed that longer reaction times during the Go/No-Go task were associated with longer N2 latency in the Go condition, as well as a higher aperiodic spectral slope and lower alpha power in the eyes-open condition during rest. Psychological well-being and impulsivity scores (WBQ and BIS questionnaires) among participants experiencing PMS symptoms were lower than those of participants not experiencing PMS symptoms. More frequent measurements across different phases of the menstrual cycle allowed for a more sensitive assessment of the influence of female sex hormones on neurophysiological indicators throughout the menstrual cycle. |
