1 - (SYM 6) Characterizing Menstrual Cycle Changes in Event-related Potentials Associated with Positive and Negative Valence Systems: The Reward Positivity and the Error-related Negativity

Despite their prevalence in clinical neuroscience, effects of the human menstrual cycle on event-related potentials (ERPs) are poorly understood. This pre-registered study used multilevel modeling to test for the presence of normative cyclical changes in two ERPs associated with positive and negative valence systems underlying psychopathology—the Reward Positivity (RewP) and the Error-Related Negativity (ERN). The RewP is an index of neural reward sensitivity that is reduced in major depression and the ERN reflects early error processing and is enhanced in anxiety and OCD. We also examined concurrence between phase-related changes in ERPs, and positive (PA) and negative (NA) affect.

A sample of 71 healthy and naturally cycling females participated in repeated EEG sessions and ecological momentary assessments of PA and NA in the early follicular, periovulatory, and mid-luteal phases. Cycle phases were verified using menses and luteinizing hormone testing. Time point (i.e., assessment number) was included as a covariate.

Intra-class correlations (ICCs) for the RewP and the ERN models were .44 and .56, respectively, suggesting that approximately half of the variance in these ERPs is attributable to within-person flux. This indicates that single administrations of these tasks may have limitations in reliably capturing stable between-person differences. ICCs for the PA and NA models were .41 and .53, respectively, indicating that affect showed both stable and fluctuating variance.

For RewP, we observed a trend-level (p = .058) fixed effect of cycle phase on the RewP such that the RewP was marginally enhanced in the mid-luteal phase as compared to the early follicular phase. There were no significant fixed effects of cycle phase on the ERN. There were no significant fixed effects of cycle phase on PA and NA.
While cycle phase did not show normative fixed effects on the ERN in this healthy sample, findings suggest that reward sensitivity may be enhanced in the mid-luteal phase as compared to the early follicular phase in some individuals¾potentially due to luteal surges in estradiol or progesterone. Model ICCs suggest that there is a substantial amount of within-person flux in ERPs and affect, which raises questions about the role of individual differences in sensitivity to hormone flux across the menstrual cycle. Additional analyses are ongoing examining whether cycle phase influences the stability and trajectory of RewP and ERN across trials within a session, which may allow more power for the modeling of random effects of cycle phase on ERPs and affect.