Evidências eletroencefalográficas e comportamentais da influência do ciclo menstrual sobre a prática da imagética motora

Abstract

Introduction: Evidence suggests the female sex steroids (FSS) effect on neural circuits involved in motor control, performance in manual dexterity and motor coordination tests and neurological diseases with motor impairment. There is a lack of studies that investigate its effects on motor cognitive processing. The sensorimotor rhythm also known as mu rhythm (with its alpha: 12-13Hz; and, beta components: 15-30Hz) observed in electroencephalography (EEG) is considered a window of opportunity to investigate the modulation of cortical areas involved in planning motor. The mu rhythm can be induced by activities such as kinesthetic motor imagery (MI) and action observation (AO), among others. Another tool used to investigate motor cognitive processing is the Hand Laterality Judgement Task (HLJT). It is able to modulate the P100 and P300 components of the Event-Related Evoked Potential (ERP) in the EEG and it has behavioral measures that allow making inferences about cognitive processes related to the spatial manipulation of body parts (in this specific case, the hands). This process is known as implicit motor imagery. Aim: In this study, we investigated whether the cortical activity and behavioral measures related to the cited tasks are modulated according to the menstrual (low hormone levels), follicular (high estrogen levels) and luteal (high progesterone levels) phases of the menstrual cycle of 31 right-handed women. Methods: These investigations gave rise to two articles. In article 1, the amplitude of P100 and NNP of the parieto-occipital region was investigated, as well as the performance in the test measured by the accuracy and response time, during the practice of HLJT in the three phases of the cycle. The analysis of generalized estimating equation (GEE) was performed to compare the phases of the cycle as a function of the amplitude of P100 and RNN, the accuracy and the reaction time, considering the possible interactions between the phases of the menstrual cycle and the characteristics of the stimulus. In the second article, the spectral activity of the mu rhythm in the sensorimotor region (C3 and C4) and of the alpha and beta bands in the other cortical regions were recorded in the three phases of the cycle during the practice of MI and AO of the right upper limb. Comparisons were made between the phases of the menstrual cycle for the variables mentioned using a Friedman test. Results with p <0.05 were considered significant. Results and conclusions: The behavioral analysis (accuracy and reaction time) of article 1 indicated better performance in HLJT during the follicular and luteal phases when compared to the menstrual phase. This result contradicts studies that demonstrate a reduction in the spatial manipulation ability of objects associated with FSS and suggests that the effect of these on motor cognitive components, possibly absent in spatial manipulation tests, is capable of favoring performance in HLJT. In article 2, it was possible to observe the beta-mu event-related desynchronization (ERD) on the left sensorimotor region (area of representation of the right hand) and beta ERD on the bilateral frontal regions during the practice of IM was significantly higher in the follicular phase when compared with the menstrual and luteal phases, suggesting the effect of estrogens on areas of motor cognitive processing. No difference between the phases of the menstrual cycle was observed on the alpha-mu rhythm during the practice of AO or MI, nor on the alpha component in several cortex regions of the cortex during MI. However, a positive correlation was observed between the amplitude of alpha and beta in several cortex regions during the practice of AO and estradiol levels in the follicular phase. These findings should be considered when using the practices of IM and AO during the training of athletes and neurofunctional rehabilitation of women. As well as they should serve as a basis for future studies that investigate the effect of the FSS on motor processing and learning.