A study carried out by three teams of researchers from the Massachusetts Institute of Technology (MIT) (United States), the Max Planck Institute for Evolutionary Anthropology and the Ludwig-Maximilia University (Germany) reveals the keys to the functioning of the gene responsible for learning of language in humans, the Foxp2 gene.
The Foxp2 gene was discovered by a group of scientists from the Wellcome Center for Human Genetics at the University of Oxford, led by Simon Fisher after being alerted from an English school of logotherapy about a group of children from the same family who had certain defects of speech and language that went back to his great-grandparents. Simon Fisher's group found a mutation in the FoxP2 gene that he identified as responsible for speech defects. In this way, they discovered the importance of this gene in the oral expression of language.
The Foxp2 protein regulates the expression of genes involved in the acquisition of language and speech
Its corresponding protein is a transcription factor that regulates the translation of other segments of DNA in its gene products; it behaves like a switch of up to a hundred genes (many of them involved in the development and organization of the nervous system) known as target. When the mutation of a chromosome occurs, this switching function is reduced to its half; consequently, the target genes of the FoxP2 protein can be regulated in the wrong way or simply have no regulation, which leads to the appearance of certain speech disorders.
It is not an exclusive gene of people although scientists argue that the gene, in humans, as a consequence of a mutation that took place millions of years ago, differs in the sequence of a few nucleotides that could be responsible for language learning of people.
In the study, the researchers integrated a human version of the Foxp2 gene into mice and found that they learned stimulus-response associations faster than their WT littermates (without the human version of the Foxp2 gene). Specifically, they had to learn to walk a "T" labyrinth, in which the mice must decide whether to turn to the left or to the right at the fork, based on the texture of the floor of the labyrinth, to obtain a reward in the form of food.
synapse
Neuronal synapses: Foxp2 protein seems to activate genes involved in neuronal connections
The first phase of this type of learning requires the use of declarative memory (memory for places and situations). Over time, these memory entries are incorporated as habits and are encoded through procedural memory, the kind of memory necessary for routine tasks, such as driving the car to work each day or performing a good tennis serve afterwards. of thousands of practice hits.
The humanized Foxp2 gene facilitates converting conscious actions into behavioral routines.
Using another type of maze, they were able to test the ability of the mice in each type of memory separately, as well as the interaction of the two types. They found that mice with humanized Foxp2 performed just like normal mice when only one of the types of memory was needed, but their performance was superior when the learning task required them to convert declarative memories into practical application knowledge with which to establish a behavior routine. The key discovery was that the humanized Foxp2 gene facilitates converting conscious actions into behavioral routines.
In this study, the researchers found that Foxp2 seems to activate genes involved in the regulation of synaptic connections between neurons in a neuronal circuit that would connect the areas of the brain involved in declarative memories and knowledge of practical application. These results raise the possibility that the humanized Foxp2 phenotype reflects a different regulation of the systems involved in declarative and procedural learning, which has enabled the human brain to speak and acquire language.
These and other adjustments promoted by the gene help to "tune" the brain differently to adapt it to speech and language acquisition, according to the researchers. These are now investigating how Foxp2 can interact with other genes to exert their peculiar effects on learning and language.