The working of our minds

Gut Bacteria Might Guide The Workings Of Our Minds

Could the microbes that inhabit our guts help explain that old idea of "gut feelings?" There's growing evidence that gut bacteria really might influence our minds.
"I'm always by profession a skeptic," says Dr. Emeran Mayer, a professor of medicine and psychiatry at the University of California in Los Angeles. "But I do believe that our gut microbes affect what goes on in our brains."
Mayer thinks the bacteria in our digestive systems may help mold brain structure as we're growing up, and possibly influence our moods, behavior and feelings when we're adults. He says, "It opens up a completely new way of looking at brain function and health and disease."
So Mayer is working on just that, doing MRI scans to look at the brains of thousands of volunteers and then comparing brain structure to the types of bacteria in their guts. He thinks he already has the first clues of a connection, from an analysis of about 60 volunteers.
Mayer found that the connections between brain regions differed depending on which species of bacteria dominated a person's gut. That suggests that the specific mix of microbes in our guts might help determine what kinds of brains we have - how our brain circuits develop and how they're wired.
Credit: Benjamin Arthur for NPR
Of course, this doesn't mean that the microbes are causing changes in brain structure, or in behavior.
But other researchers have been trying to figure out a possible connection by looking at gut microbes in mice. There they've found changes in both brain chemistry and behavior. One experiment involved replacing the gut bacteria of anxious mice with bacteria from fearless mice.
"The mice became less anxious, more gregarious," says Stephen Collins of Mc Master University in Hamilton, Ontario, who led a team that conducted the research.
It worked the other way around, too - bold mice became timid when they got the microbes of anxious ones. And aggressive mice calmed down when the scientists altered their microbes by changing their diet, feeding them pro biotics or dosing them with antibiotics.
by ROB STEIN