Language skills tied to ancient gene mutation

Scientists have found that a gene mutation that arose more than half a million years ago may be key to humans' unique ability to produce and understand speech.
Researchers from Massachusetts Institute of Technology and several European universities have shown that the human version of a gene called Foxp2 makes it easier to transform new experiences into routine procedures.
When they engineered mice to express humanised Foxp2, the mice learned to run a maze much more quickly than normal mice.
Foxp2 may help humans with a key component of learning language - transforming experiences, such as hearing the word "glass" when we are shown a glass of water, into a nearly automatic association of that word with objects that look and function like glasses, said Ann Graybiel, an MIT Institute Professor and a senior author of the study.

Foxp2 is one of several genes that scientists believe may have contributed to the development of linguistic skills in humans.
The gene was first identified in a group of family members who had severe difficulties in speaking and understanding speech, and who were found to carry a mutated version of the Foxp2 gene.

Svante Paabo, director of the Max Planck Institute for Evolutionary Anthropology, and author of the new study, found that the mice with humanised Foxp2 were better at learning to run a T-shaped maze, in which the mice must decide whether to turn left or right at a T-shaped junction, based on the texture of the maze floor, to earn a food reward.

The first phase of this type of learning requires using declarative memory, or memory for events and places.
Over time, these memory cues become embedded as habits and are encoded through procedural memory - the type of memory necessary for routine tasks.
Using another type of maze called a cross-maze, researchers found that the mice with humanised Foxp2 performed the same as normal mice when just one type of memory was needed, but their performance was superior when the learning task required them to convert declarative memories into habitual routines.
The key finding was that the humanised Foxp2 gene makes it easier to turn mindful actions into behavioural routines.

Researchers also found that Foxp2 appears to turn on genes involved in the regulation of synaptic connections between neurons. They found enhanced dopamine activity in a part of the striatum that is involved in forming procedures.
In addition, the neurons of some striatal regions could be turned off for longer periods in response to prolonged activation - a phenomenon known as long-term depression, which is necessary for learning new tasks and forming memories.
Together, these changes help to "tune" the brain differently to adapt it to speech and language acquisition, the researchers concluded.
The study appears in the journal Proceedings of the National Academy of Sciences.