Neuroscientists identified a gene mutation that arose over half a million years ago that could be the key to humans' ability to produce and understand speech.
Researchers showed human version of a gene called Foxp2 that makes it easier to transform new experiences into routine procedures, MIT reported. When mice were engineered express Foxp2 they learned to run a maze much faster than those who did not possess the gene. The finding suggests FoxP 2 could help humans transform the experience of hearing a word into an object association.
"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," said Ann Graybiel, an MIT Institute Professor, member of MIT's McGovern Institute for Brain Research, and a senior author of the study.
The researchers found mice who had been engineered to express the gene had longer dendrites (the slender extensions that neurons use to communicate with each other) in their striatum, which is the habit-forming region of the brain. The mice were also found to be better at forming synapses, which are connections between neurons.
The mice with humanized Foxp2 were better at learning to navigate a T-shaped maze. The first process in this type of leaning requires declarative memory which then become cues embedded as habits and are encoded through procedural memory.
Using a cross-maze the researchers were able to test each type of memory in the mice and found those with humanized Foxp2 performed the same as normal mice if just one type of memory was need but their performance was superior when they needed to convert declarative memories in habitual routines.
The protein produced by Foxp2 can switch genes on and off. Specifically Foxp2 turns on genes involved in the regulation of synaptic connections between neurons and enhances dopamine activity in the striatum. These changes could help the brain adapt to learning and understanding language.
The findings were published this week in the Proceedings of the National Academy of Sciences.
