Men’s Brains Respond Differently to Hungry Infant’s Crying

Researchers have uncovered firm evidence for what many mothers have long suspected: women’s brains appear to be hard-wired to respond to the cries of a hungry infant.

Researchers asked men and women to let their minds wander, then played a recording of white noise interspersed with the sounds of an infant crying. Brain scans showed that, in the women, patterns of brain activity abruptly switched to an attentive mode when they heard the infant cries, whereas the men’s brains remained in the resting state.

“Previous studies have shown that, on an emotional level, men and women respond differently to the sound of an infant crying,” said study co-author Marc H. Bornstein, Ph.D., head of the Child and Family Research Section of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the institute that conducted the study. “Our findings indicate that men and women show marked differences in terms of attention as well.”

The earlier studies showed that women are more likely than men to feel sympathy when they hear an infant cry, and are more likely to want to care for the infant.

Dr. Bornstein collaborated with Nicola De Pisapia, Ph.D., Paola Rigo, Simona DeFalco, Ph.D., and Paola Venuti, Ph.D., all of the Observation, Diagnosis and Education Lab at the University of Trento, Italy, and Gianluca Esposito, Ph.D., of RIKEN Brain Science Institute, Japan.

Their findings appear in NeuroReport.

Dr. Bornstein says this research not only helps understand the specific wiring of the brain, but helps understand how the brain has developed. (MP3 – 00:01:12, 1,140 KB)

Transcript – Dr. Bornstein says this research not only helps understand the specific wiring of the brain, but helps understand how the brain has developed.

Previous studies have shown differences in patterns of brain activity between when an individual’s attention is focused and when the mind wanders. The pattern of unfocused activity is referred to as default mode, Dr. Bornstein explained. When individuals focus on something in particular, their brains disengage from the default mode and activate other brain networks.

For about 15 minutes, participants listened to white noise interspersed with short periods of silence and with the sounds of a hungry infant crying. The patterns of their brain activity were recorded by a technique known as functional magnetic resonance imaging.

The researchers analyzed brain images from 18 adults, parents and nonparents. The researchers found that when participants listened to the typical infant cries, the brain activity of men and women differed. 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 nonparents.

Infants cry because they are distressed, hungry, or in need of physical closeness. To determine if adults respond differently to different types of cries, the researchers also played the cries of infants who were later diagnosed with autism. An earlier study of Dr. Bornstein and the same Italian group found that the cries of infants who develop ASD tend to be higher pitched than those of other infants and that the pauses between cries are shorter. In this other study, both men and women tended to interrupt their mind wandering when they heard these cries.

“Adults have many-layered responses to the things infants do,” said Dr. Bornstein. “Determining whether these responses differ between men and women, by age, and by parental status, helps us understand instincts for caring for the very young.”

In an earlier study, Dr. Bornstein and his colleagues found that patterns of brain activity in men and women also changed when they viewed an image of an infant face and that the patterns were indicative of a predisposition to relate to and care for the infant.

Such studies documenting the brain activity patterns of adults represent first stages of research in neuroscience understanding how adults relate to and care for infants, Dr. Bornstein explained. It is possible that not all adults exhibit the brain patterns seen in these studies.

Source: National Institutes of Health (NIH)

What Can Birds Teach Us About Raising Our Own Young?

Are younger siblings at a competetive disadvantage to their older brothers or sisters? What wisdom can a bird study provide to us about human sibling relationships?

Common wisdom holds that the first-laid birds in a clutch have a better chance of surviving to leave the nest. But Keith Sockman, an assistant biology professor in UNC’s College of Arts and Sciences, has discovered that first-laid eggs are, in fact, the least likely to hatch at all. His findings, based on studying a population of Lincoln’s sparrows in a remote stretch of Colorado’s San Juan Mountains, were published in the March 12,2008 issue of PLoS ONE. "I believe this is the first study to follow siblings from laying through fledging and demonstrate that the effect of laying order on hatching is very different from its effect post-hatching," said Sockman.

It is well-known that because the youngest hatchlings are too small to compete with their stronger brood-mates for the food provided by their parents, they often die. This pattern is often repeated in other animals, from beetles to marsupials to humans. But these observations have so far not allowed for whathappens to eggs before they hatch.

Female Lincoln’s sparrows usually produce three to five eggs, laying one egg a day. Monitoring the birds for three breeding seasons, Sockman and his researchers noticed that the mothers did not start incubating the eggs right away, since they had other things claiming their attention, such as foraging for food. Sockman thinks this makes it probable that first-laid eggs won’t hatch at all, besides helping ensure that a greater number of healthy, strong birds will hatch and mature into young birds.

"At these elevations, conditions can be fairly harsh even during the summer when Lincoln’s sparrows breed," said Sockman. "It’s often freezing at night, which is hard on an un-incubated egg, while daytime temperatures are warm enough to foster the growth of harmful microbes. As a result, since the mother sparrow isn’t keeping them at the most optimal incubating temperature from day one, first-laid eggs can be exposed to environmental conditions that lower the chance those embryos will ever see the world outside their shell."

"If the female did start incubating all her eggs as soon as she laid them, it would increase the probability they’d all hatch. But it would also give a huge head start to those first-laid eggs and the chicks that emerge from them, putting their younger siblings at even more of a competitive disadvantage once they begin battling for food and their mother’s attention," said Sockman.

"It may also reduce the number of eggs she is capable of laying.The mother’s careful balancing of this trade-off enables her to end up with three or four relatively equally robust offspring, instead of one or two strong hatchlings and several "runts of the litter."

Sockman plans to examine what, if any repercussions laying order has once young birds reach adulthood. "The severely competitive environment in the nest may have consequences on the individual’s ability to compete for resources and mates the following year when it is reproductively mature," said Sockman.

Keep these findings in mind as you raise your own young!

Trading Prescription Medications Among Teens

With an increase in the number of psychotropic prescriptions for adolescents there are increased chances of these prescriptions ending up in the wrong hands.

Results of a survey of school students show that 1% of all prescriptions that caregivers write for teenagers are used for non-medical purposes. 6 out 10 students with legitimate psychotropic prescriptions are contacted to redirect their prescriptions. 1% of them agree to do it and some even sell them. As many as 25% have reported that they divert the prescriptions to family and friends.

Critics hold doctors responsible for giving out too many prescriptions to teenagers. However, researchers say that the real problem might be that doctors do not adequately discuss the matter of diverted prescriptions with patients and their families.