 Additionally, the mPOA is critical for the onset and expression of parental behavior, as evidenced by increases in the immediate early gene c-fos, in experienced rat mothers or fathers when compared to controls.Also in fathers, studies have shown that when they receive ultrasonic or pheromone cues from their mates, their c-fos expression in the mPOA further increased, suggestive that rat paternal behavior is mediated through the mPOA but activated by direct interactions with a mate.Large lesions of the mPOA disrupt the onset of maternal behavior, nest-building, and pup retrieval, with the lateral projections being especially critical.