RT Journal Article
SR Electronic
T1 Peak gamma frequency and cortical laminar processing are modified across the healthy menstrual cycle
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 219196
DO 10.1101/219196
A1 R. L. Sumner
A1 R. L. McMillan
A1 A. D. Shaw
A1 K. D. Singh
A1 F. Sundram
A1 S. D. Muthukumaraswamy
YR 2017
UL http://biorxiv.org/content/early/2017/11/14/219196.abstract
AB Fluctuations in gonadal hormones over the course of the menstrual cycle are known to cause functional brain changes and are thought to modulate changes in the balance of cortical excitation and inhibition. Animal research has shown this occurs primarily via the major metabolite of progesterone, allopregnanolone, and its action as a positive allosteric modulator of the GABAA receptor. Our study used EEG to record gamma oscillations induced in the visual cortex using stationary and moving gratings. Recordings took place during twenty females' mid-luteal phase when progesterone and oestradiol are highest, and early follicular phase when progesterone and oestradiol are lowest. Significantly higher (~5 Hz) gamma frequency was recorded during the luteal compared to the follicular phase for both stimuli types. Using dynamic causal modelling these changes were linked to stronger self-inhibition of superficial pyramidal cells in the luteal compared to the follicular phase. In addition the connection from inhibitory interneurons to deep pyramidal cells was found to be stronger in the follicular compared to the luteal phase. These findings show that complex functional changes in synaptic microcircuitry occur across the menstrual cycle and that menstrual cycle phase should be taken into consideration when including female participants in research into gamma-band oscillations.