An international study led by Thomas Pizzorusso, a professor at the University of Florence, showed that the eyes affect brain development. The use of vision increases the number of microRNA molecules, which in turn stimulate the development of brain circuits.
MicroRNA molecules regulate how information in genes is transformed into functional macromolecules. Observing the development of the visual bark, the researchers found that it contains a large number of these molecules. In particular, the molecules increase greatly during the functional maturation period in early childhood. According to researchers, microRNA molecules and vision could be linked by virtue of a virulent circle.
The team focused on a particular microRNA molecule, the miR-132. The more miR-132 there are, the greater the functional maturation of vision-related neurons, the excitatory neurons. Without the molecule, development stops and 3D vision is missing. At the same time, visual stimulation induces the production of miR-132. The molecule itself allows proper vision development, which again promotes the rise of miR-132. So brain development stimulates visual development and visual development stimulates brain development.
The discovery opens new perspectives for the study of schizophrenia and autism. In these diseases, gene expression responds abnormally to external experiences. This leads to problems during development. The study identifies some genes controlled by the miR-132 molecule. The cause of some psychiatric illnesses might reside in the way the molecule translates the stimuli.
The molecular factors that mediate stimulation and brain development are relevant even in adulthood. The miR-132 molecule is not present in the brain of patients afflicted with Alzheimer's. This suggests that the absence of a mediator between external and internal world can contribute to brain degeneration.