The Effect Of Physiological Cycle On The Plasticity Of The Motor Cortex In Women

Backgrounds: As an important feature of gender differences, menstrual cycle accompanied ovarian hormone changes and brain function alterations. Plasticity is an important property of brain, which was influenced by many factors. Few studies investigated the cortical plasticity variations among different period of the menstrual cycle. Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique, which is widely used to study cortical plasticity. The present study employed TMS to explore cortical plasticity among different phases in menstrual cycle non-invasively.Methods: 47 participants were recruited in the present study (7 males). Female were divided into 3 groups according to menstrual cycle: menstrual phase group,follicular phase group and luteal phase group. TMS protocols were applied onto the primary motor cortex (M1), motor evoked potentials amplitude (MEPs amplitude) were recorded before and after TMS interventions.Results: With cTBS protocol,the MEPs significantly decreased in all groups except for the luteal phase group(P<0.05), the luteal phase group showed significant increase in MEPs; while 10 Hz rTMS protocol leads to potentiation of MEPs in all group except for the follicular phase which lacks a significant change following the stimulation (P>0.05).Conclusions: TMS-induced cortical plasticity is significantly affected among different phases of menstrual cycle, there were gender differences in cortical plasticity.The cortical excitability varies with the different phases of menstrual cycle.