al Magnetic Resonance Imaging (fMRI). The brain activity of a group of women was examined twice during their menstrual cycle. Each time they went into the MRI, they were presented with virtual slot machines showing different probabilities of winning. When women anticipate uncertain rewards, they activate the brain regions involved in processing emotions, particularly the amygdala and the orbitofrontal cortex, to a greater extent during the follicular phase (4 to 8 days after the start of the period) than during the luteal phase (6 to 10 after the LH7 hormone surge). These results demonstrate increased reactivity of the female recompense system during the follicular phase, which is also the phase in which the estrogens do not oppose the progesterone. In order to determine the gender-related differences of reward system activation, the same experiment was carried out on a male group. Result: when men anticipate rewards, they mainly activate a region involved in motivation for obtaining rewards, the ventral striatum, whereas in women, it is a region dealing with emotions, the amygdalo-hippocampal region, which is the most highly activated.
These conclusions could be applied to rewards other than monetary. Take receptiveness and desire, for example, two qualities that are supposed to facilitate procreation and are seen during the period of ovulation. It could be envisaged that the increase in activity of certain regions of the female brain during the follicular phase would modulate behavior linked to obtaining rewards, such as approach behavior during reward anticipation and hedonistic behavior when the reward is received.
These results, at the border between neuroendocrinology and neurosciences, provide a better understanding of the fundamental role of gonadal steroid hormones on reward processing, particularly in behavioral processes such as motivation and learning. They also important in understanding the dysfunction of the reward system observed paPage: 1 2 3 4 Related biology news :1
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