While babies, toddlers and young children are taking in and making sense of the world, their brain cells are wiring themselves together willy-nilly, creating super-dense networks of interwoven neurons. But as we reach and progress through adolescence, neuroscientists have observed, a period of intensive “synaptic pruning” occurs in which those networks are thinned and the strongest and most evolutionarily useful remain.

In a study published last week, scientists from the University of California at Davis say they believe the slowed fluctuations observed during the delta phase of teens’ sleep may be evidence of that pruning process at work.

And since major mental illnesses such as schizophrenia appear to take root during adolescence, the authors of the study say the changing architecture of sleep may offer clues as to how and when mental illness sets in.

“There are so many trials where pregnant women are supplemented with omega-3 fatty acids and they’ve all got different results,” said lead study author Jacqueline Gould, a researcher at the Women’s and Children’s Health Research Institute in Adelaide, Australia. “We found that there was neither a positive nor a negative effect on visual or neurological outcomes.”

The Australian team, who published their findings in The American Journal of Clinical Nutrition, analyzed data from 11 clinical trials with a total of 5,272 participants who were randomly assigned to take omega-3 supplements or placebos during the last half of their pregnancies.

Across the trials, the amount of omega-3 taken by the mothers ranged from 240 to 3,300 milligrams per day. And the ages at which children’s brain and vision development were assessed ranged from newborn to 7 years old.

According to the researchers, most of the clinical trials included too few participants to distinguish subtle differences expected from nutritional studies, excluded complicated pregnancies (in which greater differences might have been seen) and didn’t follow the children long enough during development.

“Our analysis highlights that more research is needed,” Gould told Reuters Health.

Omega-3 fatty acids are crucial for healthy fetal brain development and are commonly found in fatty fish such as tuna, mackerel and sardines. Human brains and eyes contain large amounts of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), both forms of omega-3.

Developing fetuses can get DHA from their mothers’ fat stores, and from food and supplements they consume during pregnancy.

“Dr. Stern was noted for his often poetic language in describing how children respond to their world — how they feel, think and see. He wrote one of his half-dozen books in the form of a diary by a baby. In another book, he told how mothers differ psychologically from women who do not have children. He coined the term “motherese” to describe a form of communication in which mothers are able to read even the slightest of babies’ emotional signals.

Dr. Stern, who did much of his research at what is now Weill Cornell Medical College and at the University of Geneva, drew inspiration from Jay S. Rosenblatt’s work with kittens at the American Museum of Natural History in the 1950s. Dr. Rosenblatt discovered that when he removed kittens from their cage, they made their way to a specific nipple of their mother’s even when they were as young as one day old. That finding demonstrated that learning occurs naturally at an exceptionally early age in a way staged experiments had not.

Dr. Stern videotaped babies from birth through their early years, and then studied the tapes second by second to analyze interactions between mother and child. He challenged the Freudian idea that babies go through defined critical phases, like oral and anal. Rather, he said, their development is continuous, with each phase layered on top of the previous one. The interactions are punctuated by intervals, sometimes only a few seconds long, of rest, solitude and reflection. As this process goes on, they develop a sense that other people can and will share in their feelings, and in that way develop a sense of self.

These interactions can underpin emotional episodes that occur years in the future. Citing one example in a 1990 interview with The Boston Globe, Dr. Stern told of a 13-month-old who grabbed for an electric plug. His alarmed mother, who moments before had been silent and loving, suddenly turned angry and sour. Two years later, the child heard a fairy tale about a wicked witch.

“He’s been prepared for that witch for years,” Dr. Stern said. “He’s already seen someone he loves turn into something evil. It’s perfectly believable for him. He maps right into it.”

Dr. Stern described such phenomena in 1985 in “The Interpersonal World of the Infant,” which the noted psychologist Stanley Spiegel, in an interview in The New York Times, called ‘the book of the decade in its influence on psychoanalytic theory.’”

Now researchers have been able to show that a particular type of behavioral therapy called the Early Start Denver Model (ESDM) not only improves autism symptoms, but actually normalizes brain activity and improves social behavior.

Autism is a neurodevelopmental disorder that starts to become very apparent around age 3. The main signs and symptoms of autism involve communication, social interactions and repetitive behaviors. According to the latest statistics from the U.S. Centers for Disease Control and Prevention, one in 88 children currently is diagnosed with autism, including one in 54 boys.

“Early intervention alters the trajectory of the brain and social development in children with autism,” says Geraldine Dawson, the lead study author who developed the ESDM therapy along with study co-author Sally Rogers.

Dawson was a researcher at the University of Washington when she helped devise ESDM; she’s now the chief science officer for the advocacy and research group Autism Speaks and a professor at the University of North Carolina. Rogers is a professor and researcher at the University of California Davis MIND Institute.

ESDM therapy uses teaching methods from ABA ,or applied behavioral analysis, the traditional one-on-one interaction between a child and the therapist.

But rather than sitting at a desk next to the child — where a teacher or therapist breaks down complex tasks into small components and gives tangible reinforcements — children receiving ESDM are sitting on the floor, playing with their therapist or parents.It can be done just about anywhere, and Dawson says the play-based method of engaging a child helps him or her develop a social relationship.

On the flip side, those children whose mothers consumed the most fish while pregnant were the least likely to exhibit fidgety, distracted, and impulsive behaviors in class, according to the study of 604 children published Monday in the Archives of Pediatrics and Adolescent Medicine.

At first blush, this finding appears contradictory because most of the mercury we consume comes from fish. “It seems a little paradoxical,” said study co-author Dr. Susan Korrick, an assistant professor of medicine at Brigham and Women’s. “But fish consumption doesn’t necessarily correlate with mercury levels since you could eat a high amount of fish that are low in mercury.”

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Fatty kinds of fish such as salmon, tuna, and sardines have higher levels of omega-3 fatty acids, which are thought to be crucial for cognitive function. All types of fish have a host of nutrients such as vitamin D, B-12, and iodine, which could play a role in brain development as well.

While government agencies have advised pregnant women to limit their fish intake to no more than two six-ounce servings a week, Korrick said they might want to aim for three or four servings of low-mercury fish such as salmon, canned light tuna, haddock, cod, and shrimp. (Albacore tuna has more mercury, so consumption should be limited to six ounces a week.)

The key is for pregnant women to avoid fish known to have high mercury levels, including swordfish, shark, tilefish, and king mackerel, Korrick added.