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“Electrical

cortical activity is segregated in discrete frequency bands (Buzsaki, 2006). Among the five mayor frequency bands, alpha and theta frequencies fluctuate predictably during the menstrual cycle, indicating an association between sex hormone fluctuations and neural activity (Becker Cabozantinib nmr et al., 1982, Creutzfeldt et al., 1976 and Brötzner et al., 2014). Analysis of EEG data reveal a lower frequency in the alpha band in late follicular phase, when estradiol is elevated but progesterone is low, compared to early follicular phase, when estradiol as well as progesterone is low, or luteal phase, when estradiol as well as progesterone is elevated (Brötzner et al., 2014). Theta oscillations show a higher frequency in the follicular compared to the luteal menstrual cycle phase (Becker

et al., 1982). How endogenous changes in sex hormone levels during the menstrual cycle contribute to inter- as well as intra-individual differences in cognitive performance and its underlying neural Ixazomib ic50 activity remains a fundamental issue. Previous studies correlated cognitive performance either with an event-related potential (ERP) or sex hormone level. Following presentation of visual stimuli, the temporal sequence of an ERP consists of C1, P1, and N1. This sequence may represent sensory processing (C1), early categorization (P1), and identification of objects (N1) (Klimesch, 2011). Among the three components, P1, with a post-stimulus latency of approximately 100 ms, may be the earliest equivalent for top-down modulation of sensory input. In goal-directed top-down

attention paradigms, expected perceptive contents are categorized as relevant or irrelevant information within a tenth of second (Thorpe et al., 1996 and Rousselet et al., 2007; for review see Klimesch, 2011). Furthermore, Hanslmayr and colleagues describe that during a visual discrimination task enhanced early ERP components (P1 and N1 amplitude) are related to good performance (Hanslmayr et al., 2005). Several lines of arguments indicate that at least a fraction of P1 equals synchronized alpha oscillations: (1) P1 latency and period of alpha oscillation are approximately 100 ms, (2) P1 is predicted by phase alignment in alpha (Gruber et al., 2005) and (3) similar time domain of alpha oscillations and Casein kinase 1 attentional blink (Hanslmayr et al., 2011). One influential interpretation of P1 is the inhibition model (Klimesch et al., 2007). According to the inhibition model, phasic synchronization of alpha oscillation is associated with an increase in signal to noise ratio for relevant information, but tonic synchronization with suppression of irrelevant information. Both processes improve working memory and attention performance (Klimesch et al., 2007). Ovarian steroid hormones modulate neural circuits and cognitive performance not directly related to reproductive behavior.