The female brain undergoes major structural modifications during the cycle, with connections between neurons capable of increasing or decreasing dramatically (up to a factor of three every five days) under the influence of estrogens.

noli's read

Research strongly supports the idea that sex hormones shape the structure and activity of the brain. A magnetic resonance imaging study conducted by Taylor et al. (observational study) confirms changes in functional connectivity in the human brain throughout the phases of the cycle. Nevertheless, the numerical data suggesting a variation of a factor of three come from research on rodents, notably from classic experimental work such as that of Woolley and McEwen on synaptic connections. At present, technology does not allow for the measurement of such microscopic fluctuations in the living human. Transposing these dramatic ratios to the daily human experience therefore constitutes an extrapolation. However, this cyclical plasticity remains a fascinating avenue for better understanding the natural variations in our mental clarity and well-being throughout the month.

the sources

No named source held this one up — that absence is part of the verdict.