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From the article:

Participants underwent a fear-conditioning paradigm in which two of four photographs of neutral male faces were paired with a loud burst of white noise. Following the conditioning, the subjects underwent fear extinction, in which two photographs – only one of which had been paired with the noise – were again presented, but this time with no noise stimulus. The next day, subjects were shown all four photographs again, including the two that had been presented in the extinction phase and thus ready for extinction recall, and two of them without previous extinction – thus subject to fear recall. During all presentations, the researchers measured skin conductance responses (SCR), a peripheral readout of fear expression, and brain oscillations measured by electroencephalography.

Mr. Bierwirth said: “We found stronger peripheral fear expression (via SCR) during fear recall and extinction recall under low-E2 conditions, that is, in men and in OC women, compared to mid-cycle women with higher E2 [estradiol] levels. Most importantly, we also observed enhanced theta oscillations in the medial prefrontal cortex and especially in the dorsal anterior cingulate cortex (dACC), in men and OC women compared to MC women.”

Importantly, the authors also point out that subjects were examined during their natural E2 status. They were not randomized to experimentally manipulated estrogen levels and so causal inferences about estrogen cannot be drawn.

Fear recall-related dACC theta oscillations were attenuated in women with higher E2 levels, which, importantly, supports previous findings suggesting a protective role for E2 against fear overexpression during the recall of fear and extinction memories. The data demonstrate that peripheral and brain oscillatory correlates of fear memory recall do not differ between the sexes per se but vary with E2 status, even among women.

From the publication:

Rodent studies show that theta oscillations (4–8 Hz) in the prelimbic cortex (homolog of the primate dACC) were augmented during fear recall and reduced to baseline levels during extinction recall.

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