How does our brain work to keep the objects we see stable, even with our eyes moving? This was the starting point of the study carried out by a team of researchers from the University of California, San Diego School of Medicine and the Shiley Eye Institute (USA).
To do this, the scientists labeled specific sets of neurons in the brain that are the ones that make specific connections . Thanks to this particular approach, scientists can look at the individual components of the visual network and identify the exact genes that turn those cells on and form the appropriate connections.
Analysis of the results tested in both laboratory mice and human cells revealed that the expression of contactin-4 (an adhesion molecule) was highly specific in the cells of the eye that participate in image stabilization . After testing the mutation of this molecule, they found that the brain circuit was not well formed and the visual cells did not “understand” properly with the brain. And it is that contactin-4 is necessary to form the circuits of the cells for a constant connection between the brain and the eyes.
By examining which other proteins bound contactin-4, they found that the amyloid precursor protein (associated with Alzheimer’s disease) was essential to control the development of visual circuits. Thus, that kind of molecular “glue” that makes the brain connections with the eyes allow us to visualize sharp and stabilized images, is made up of contactin-4 and the amyloid precursor protein.
“In the visual system, the precise connections between the eyes and the brain help to see specific things and ensure that those images are clear and sharp. The sensors in the eye also detect movement and connect to the brain in the right way to tell their eyes to move in the right direction without blurring. Until now, we didn’t really understand how the eye and brain controlled this at the molecular level , “says study leader Andrew D. Huberman.
The work has been published in the journal Neuron .
