The blind also have a Stripe of Gennari

The Stripe of Gennari develops even in those who are blind from birth and does not degenerate, despite a lack of visual input. This was discovered by Robert Trampel and colleagues from the Max Planck Institute for Human Cognitive and Brain Sciences using magnetic resonance imaging.

The Stripe of Gennari (right: subjects with normal vision, left: blind subjects) shows up as a thin dark line in the sulcus calcinarus (white) which surrounds the primary visual cortex. © Max Planck Institute for Human Cognitive and Brain Sciences

This bundle of nerve fibers, which is approximately 0.3 mm thick, is not exclusively responsible for optic information. In the blind, it might play a greater role in processing tactile stimuli. This could contribute to an enhanced sense of touch and support fast reading of Braille.

The Stripe of Gennari – also known as the 'Stria of Gennari' – transverses the gray matter of the primary visual cortex as a distinct white line. ''Although the visual cortex is one of the best-studied parts of the brain, and the Stripe of Gennari is a rather obvious structure, why it develops and what its function is has not previously been studied in detail'', explains Robert Trampel from the Max Planck Institute for Human Cognitive and Brain Sciences. ''An obvious connection with sight was assumed."

However, as is now clear, this cannot be the only function of the stripe of Gennari: In a functional magnetic resonance imaging (fMRI) study, the researchers found the stripe of Gennari in the brains of congenitally blind subjects. ''This brain structure therefore can't exclusively be involved in vision and must be capable of carrying out other tasks'', says Trampel.