Some babies are born with early blindness due to dense bilateral congenital cataracts, requiring surgery to restore their sight. This period of several months without vision can leave a lasting mark on how the brain processes visual details, but surprisingly little on the recognition of faces, objects, or words. This is the main finding of an international study conducted by neuroscientists at University of Louvain (UCLouvain), in collaboration with Ghent University, KU Leuven, and McMaster University (Canada), published in the prestigious journal Nature Communications.
Using brain imaging, the researchers compared adults who had undergone surgery for congenital cataracts as babies with people born with normal vision. The results are striking: in people born with cataracts, the area of the brain that analyzes small visual details (contours, contrasts, etc.) retains a lasting alteration from this early blindness. On the other hand, the more advanced regions of the visual brain, responsible for recognizing faces, objects, and words, function almost normally. These "biological" results have been validated by computer models involving artificial neural networks. This distinction between altered and preserved areas of the brain paves the way for new treatments. In the future, clinicians may be able to offer visual therapies that are better tailored to each patient.
"Babies' brains are much more adaptable than we thought," explains Olivier Collignon, Professor at University of Louvain (UCLouvain). "Even if vision is lacking at the very beginning of life, the brain can adapt and learn to recognize the world around it even on the basis of degraded information."
These findings also challenge the idea of a single "critical period" for visual development. Some areas of the brain are more vulnerable to early vision loss, while others retain a surprising capacity for recovery. "The brain is both fragile and resilient," adds Olivier Collignon. "Early experiences matter, but they don't determine everything."
This research was funded by an ERC Starting Grant awarded to Olivier Collignon, Professor at the Institute for Psychological Research at University of Louvain (UCLouvain), as well as by the Jacques Moulaert Fund.
