Brain scans show women's brains appear to be hard-wired to respond to the cries of a hungry infant, but men's brains are not, U.S. researchers say. Marc H. Bornstein, head of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health, and colleagues analyzed brain images from 18 adults, parents and non-parents, who were lying at rest as functional magnetic resonance imaging monitored their brain activity. The researchers played a recording of white noise interspersed with the sounds of an infant crying. The study, published in the NeuroReport, found the brain scans showed that, in the women, patterns of brain activity abruptly switched to an attentive mode when they heard the infant cries, but the men's brains remained in the resting state. When hearing a hungry infant cry, women's brains were more likely to disengage from the default mode, indicating that they focused their attention on the crying. In contrast, the men's brains tended to remain in default mode during the infant crying sounds. The brain patterns did not vary between parents and non-parents, the study said.