Rats in proestrus-estrus present more attention behaviors toward males and exhibit higher prefrontal-parietal EEG synchronization

Abstract

According to the different stages of the estrous cycle, female rats exhibit behavioral changes associated with variations in sex hormone levels that affect the functionality of certain brain regions. In this study, we characterized the attention that female rats paid to a sexually-experienced male and the degree of electroencephalographic (EEG) activation and coupling between the medial prefrontal and posterior parietal cortices during antagonistic phases of the estrous cycle (proestrus-estrus vs. diestrous). The degree of attention paid to the stimulus was measured by the number of nose pokes performed while the rats were in a sexual incentive motivation box. EEGs were recorded in two conditions: a) awake-quiet state with no male rat present; and b) awake-quiet state in the presence of a male. Only during proestrus-estrus did the females show lower latency with a higher frequency and duration of nose pokes. In both cortices, the receptive females presented higher absolute power in all EEG bands recorded in the presence of the male, regardless of the phase of the estrous cycle. They also had greater EEG coupling between the medial prefrontal and posterior parietal cortices of the left hemisphere in all EEG bands regardless of the presence of a male. The higher synchronization between prefronto-parietal areas could be associated with the greater attention paid to, and adequate processing of, the sexual stimuli emitted by the male. Hence, it is probable that manifesting the proceptivity and receptivity behaviors characteristic of the proestrus-estrus phase requires a higher functional coupling between the prefrontal and parietal cortices.