Scientists have discovered a gene mutation that arose more than half a million years ago, and could be the key to humans' unique language ability.
Researchers from MIT 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.
Senior author of the study, Ann Graybiel, said that the findings suggest that 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.
Foxp2 is one of several genes that scientists believe may have contributed to the development of these linguistic skills. 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.
Using a maze called a cross-maze, the MIT team were able to test the mice's ability in each of type of memory alone, as well as the interaction of the two types. They found that the mice with humanized 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 therefore that the humanized Foxp2 gene made it easier to turn mindful actions into behavioral routines.
The protein produced by Foxp2 was a transcription factor, meaning that it turned other genes on and off. In the study, the researchers found that Foxp2 appeared to turn on genes involved in the regulation of synaptic connections between neurons. They also 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.