Sex differences in PPI are considered to be mediated by fluctuating hormones over the ovarian cycle based on the observations of more PPI in women during the (low estrogen) follicular phase relative to the (high estrogen) luteal phase (Swerdlow et al, 1997; Jovanovic et al, 2004).
Prepulse inhibition (PPI) of the startle response is sensitive to sex with women showing less PPI compared with age-matched men and varies according to the menstrual cycle in women.
Relatively less is known about sex differences in prepulse facilitation (PPF).
We hypothesized that (i) premenopausal women would show less PPI compared with young men of similar ages, (ii) postmenopausal women and similarly aged men would show no or a reduced sex difference in PPI, and (iii) PPI would be negatively correlated with estrogen level especially in premenopausal women.
An opposite pattern of effects was expected for PPF but with limited confidence, given the lack of robust previous data on that part of our investigation.
In addition, the premenopausal women were required to have 26–30 days menstrual cycle determined using the standard ‘counting forward and backward’ method.