A young brain has much to learn – including how it should interpret information from both eyes and collate it into a meaningful image of the environment. Hence, the cells in the visual cortex establish connections with each other during brain development to enable the optimum processing of visual environmental stimuli. In some cases, however, the signals from one eye do not correspond with those from the other eye, for example in children with strabismus. This can result in the incorrect “wiring” of the eyes to the cerebral cortex. The resulting visual weakness can often be corrected by temporarily covering the dominant eye.
When scientists from Tobias Bonhoeffer’s department examined the activity of neurons from upstream brain areas in mice, in particular the thalamus, during a temporary closure of the eye, they made an astonishing discovery: these cells did not simply relay information from the eyes to the cerebral cortex but also altered their signals in response to the eye closure. “This was completely unexpected, as it has been believed for over 50 years that the thalamus only forwards information and is not actively involved in learning processes,” reports Tobias Rose, leader of the study.