Influence of sex, menstrual cycle, and hormonal contraceptives on egocentric navigation with or without landmarks
Identificadores
URI: http://hdl.handle.net/10481/67305Metadata
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Egocentric navigation Landmarks Sex differences Menstrual cycle phase Hormonal contraceptives Sex hormones
Date
2020Abstract
This study examines the influence of sex, menstrual cycle, hormonal contraceptives (HC) and sex
hormone levels in following egocentric navigation instructions with or without landmarks. Estradiol
seem to bias the reference frame for navigation during estrous cycle of female rats. However, previous
studies in humans found no differences in overall navigation between women in their early follicular
and mid-luteal menstrual cycle phases, whose performance was worse than that of men. Our study
hypothesis was that the performance of women would be improved during the peri-ovulatory phase
and would remain the same during placebo and active phases of HC users. The study included 21
men, 62 women with natural menstrual cycle (21 during early follicular phase, 20 during periovulatory phase, and 21 during mid-luteal phase), and 38 women that were receiving HC (13 during
placebo phase and 25 during active phase). The men outperformed the women with a natural
menstrual cycle when following egocentric instructions without landmarks. However, the women’s
performance varied according to the phase of their menstrual cycle, differing from men during early
follicular and mid-luteal phases but not during the peri-ovulatory phase. The use of HC also improved
the performance of women to the extent that the difference with men disappeared. No differences
were observed between HC-placebo and HC-active user groups during egocentric navigation without
landmarks and among all groups during egocentric navigation with landmarks. Analysis of salivary
hormones showed that testosterone levels were higher in men and that estradiol levels in women were
higher during peri-ovulatory and mid-luteal phases and also in HC users. Progesterone levels were
higher in women during the mid-luteal phase. These results appear compatible with beneficial effect
of testosterone and estradiol on egocentric navigation without landmarks and with a block of this
effect produced by progesterone.