A.Y li¹ (), H Grotzinger¹, E Murata¹, E.G Jacobs¹, T.C Sprague¹; ¹University of California, Santa Barbara

Working memory (WM) is the ability to temporarily store and manipulate information to guide later behavior (Baddeley, 2010; Ma et al., 2014), and recent studies have shown that WM information is stored by distributed activity across early visual cortex and higher areas including parietal and prefrontal cortex (PFC) (Christophel et al., 2017; Curtis & Sprague, 2021). While most studies average data across participants, there is important evidence that these areas (especially PFC) show variations in neural function across the menstrual cycle, and measures of cognitive function (e.g., n-back) reflect these hormone-related fluctuations (Jacobs & D’Esposito, 2011). However, this previous work does not address how these hormone fluctuations impact aspects of visual WM performance, including capacity, precision, and inter-trial serial dependence (Fischer & Whitney, 2014; Bliss et al., 2017). This is important, because visual WM is a tractable system for modeling relationships between neural function and behavior in humans (Li et al., 2021). Here, we employed dense sampling methods (Pritschet et al., 2021) to assay WM performance across n = 6 participants’ natural menstrual cycles. At each of ~15 sessions per participant (approximately every other day), we measured WM capacity (Change Localization Task; Zhao et al., 2023) and WM precision (memory guided saccade [MGS] task, Funhashi et al., 1989; Li & Sprague, 2023), along with salivary measures of ovarian hormones (estradiol/progesterone) and survey measures of state anxiety, sleep quality, and caffeine intake. We observed fluctuations in visual WM performance as measured by MGS response time, precision, and magnitude of serial dependence throughout the menstrual cycle, while WM capacity was remarkably stable. Importantly, these differences could not be explained by variations in measures of sleep quality or anxiety. This implies that the rapid fluctuation of ovarian hormones may be responsible for the change in visual WM performance measured with the MGS task.

Acknowledgements: UCSB Undergraduate Research and Creative Activities Awards; Sloan Research Fellowship; Ann S. Bowers Women's Brain Health Initiative