There is much that we don't know about the human brain, but scientists are learning more on how 'humanizing' brains of other species affects cognitive functions.
An international team of researchers spliced the human brain's language gene into mice, finding that the gene made the mice much smarter.
Published in the Proceedings of the National Academy of Sciences, the team of scientists genetically engineered the human version of the Foxp2 gene into mice. The Foxp2 gene is linked to language and learning and is common in both humans and mice.
Conducted at MIT and several European universities, researchers placed the mice with humanized brains and a control group of mice in mazes and trained them to navigate and find chocolate.
The researchers found that when the maze included visual and sensory cues to hint where the food was, the genetically enhanced mice learned to find their way through the maze in about eight days compared to the 12 days it took the normal-minded mice.
"This really is an important brick in the wall saying that the form of the gene that might have allowed us to speak may have something to do with a special kind of learning, which takes us from having to make conscious associations in order to act to a nearly automatic-pilot way of acting based on the cues around us," says study co-author Ann Graybiel, a neuroscientist at MIT and the McGovern Institute for Brain Research.
When the researchers removed the visual cues, forcing the mice to learn by the feel of the maze floor, the control mice did just as well as the genetically humanized mice.
The mice with the language gene performed the best when they were faced with being able to solve a puzzle in two ways. The genetically smarter mice were able to solve the puzzle faster than the control mice.
The goal of the research was not to create "Pinky and the Brain" intelligence in lab rats, but rather to understand more about Foxp2, the gene that plays the key role in human learning and language.
The study suggests that Foxp2 allows the brain to switch from remembering things consciously through declarative learning, like "turn left at the gas station" for example, to remembering things unconsciously through procedural learning, like "turn when the floor changes from tile to carpet."
"No one knows how a child can learn to speak, but if we somehow think that part of human language learning is helped by being able to make associations rapidly and easily, between things in the world and sounds corresponding to those objects, then this gene might help with that process," Graybiel says.
When children learn to speak they first mimic the words they hear. The study concludes the ability to switch from declarative and procedural memory "is a crucial part" of the learning process.
