Putting very little babies through numerous medical procedures is especially challenging for physicians, in part because reducing the pain they experience is so difficult.

Typically for patients, "the preferred method of reducing pain is opiates. Obviously you don't want to give opiates to babies," says neurologist Regina Sullivan of NYU Langone Medical Center. "Also, it's difficult to know when a baby is in pain and not in pain."

In recent years, research has shown environmental factors, like a mother or caregiver having contact with a baby during a painful procedure, appears to reduce the amount of pain felt by the baby, at least as indicated by the child's behavior, Sullivan said. But she and Gordon Barr of the University of Pennsylvania, an expert in pain, were interested in whether a mother's presence actually changed the brain functioning of a baby in pain.

So Sullivan and Barr turned to rats. Specifically mama and baby rats who were in pain. And they found that hundreds of genes in baby rats' brains were more or less active, depending on whether the mothers were present. Sullivan and Barr presented their committee peer-reviewed research before the Society for Neuroscience annual meeting Tuesday.

They gave mild electric shocks to infant rats, some of which had their mothers around and others who didn't. The researchers analyzed a specific portion of the infants' brains, the amygdala region of neurons, which is where emotions like fear are processed. "We found that the pattern of gene expression was very different in the two conditions," Barr said. "Many of the genes that were changing because the mother was present are later related to brain development. ... We know that having the mother is not innocuous, it is a major shaper."

But it's not clear yet what the long-term impacts of such pain therapy are on these babies. Sullivan has previously done research, using animals, on what happens to babies when a caregiver is around while pain is inflicted. "We have evidence from other experiments, having repeated pain with an attachment figure [present], produces a brain susceptible to psychiatric disorders," Sullivan said. "I don't think the infants can tell the difference" as to who and what is the source of the pain.

"These procedures being done on an infant may be very beneficial in that moment in time," Barr said. "We do want to reduce the pain but we need to think about what are the long term consequences."

That will be the next question for researchers: what happens to these brains and babies in the future, long after they experience pain.