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Regular version of the site

Book chapter

Effect of a healthy menstrual cycle on gamma oscillations measured with MEG

P. 35-41.
Manyukhina Viktoriya, Rostovtseva E., Kostina E., Prokofyev A., Obukhova T., Nikolaeva A., Stroganova T., Orekhova E.

A balance between neural excitation and inhibition (E-I balance) is pivotal for nor-
mal cognitive functioning and is disturbed in neuropsychiatric disorders. Gamma oscillations
(30–120 Hz) induced in the visual cortex by moving gratings arise through an interaction of
excitatory and inhibitory neurons and are sensitive to the E-I balance. It has been suggested
that suppression of the gamma response power caused by increasing the velocity of visual
motion (‘gamma suppression slope’, GSS) can help to assess the E-I balance in neurologi-
cal disorders (Orekhova et al., 2018a; Orekhova et al., 2018b). However, it is still unknown
whether normal fluctuations of excitatory and inhibitory neurotransmission — such as those
observed during a healthy menstrual cycle — also affect the GSS. To answer this question,
we examined visual gamma oscillations in 18 healthy females during the follicular and lu-
teal phases of their menstrual cycles, using magnetoencephalography. We found that gam-
ma frequency and amplitude were higher in the luteal than in the follicular phase, which
suggests their sensitivity to cyclic changes in excitation and inhibition. The GSS, however,
remained stable, suggesting stability of the E-I balance in healthy women. Our results have
implications for research in disorders characterized by abnormal cyclic fluctuations of the
E-I balance, including premenstrual dysphoric disorder and catamenial epilepsy.