Mice engineered to carry a human version of the 'language gene' can learn to navigate a maze faster than normal mice. The study offers some insight into how humans evolved to produce and understand speech.
The human version of the gene, Foxp2, is linked to the development of language. It was identified in the 1990s, when an entire family with severe speech difficulties was found to possess a mutated version of the gene. This new study, published in PNAS, provides evidence that the gene is involved in the processing of experiences, such as words or routes, into unconscious habits.
'This really is an important brick in the wall saying that the form of the gene that 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 Professor Ann Graybiel, a member of MIT's McGovern Institute for Brain Research in the USA, and a senior author of the study.
Foxp2 produces a protein that switches other genes on and off, called a transcription factor. In the study, the researchers found that Foxp2 seemed to turn on genes that regulate neuron connections. The genetically engineered mice were observed to have longer dendrites - the tendrils that neurons communicate with - in the striatum, a part of the brain involved in habit formation. Their dopamine levels were enhanced and their striatal neurons were also better at forming new connections as well as being silenced (which allows learning and memory formation).
These brain changes were found to impact behavior, as researchers found that the mice with human version of Foxp2 were several days faster at learning to run a T-shaped maze, where the mice must decide whether to turn left or right based on landmarks and the floor texture to earn a chocolate reward.
'No one knows how the brain makes transitions from thinking about something consciously to doing it unconsciously', Professor Graybiel said in Reuters. 'But mice with the human form of Foxp2 did much better'.