Cerebral Achromotopsia
Cerebral achromatopsia is a chronic condition where a person is unable to see color, but they are still able to recognize shape and form. Cerebral achromatopsia differs from congenital achromatopsia in that it is caused by damage to the cerebral cortex as opposed to abnormalities in the retinal cells. The search for the color center was motivated by the discovery that lesions in the ventral occipital lobe led to color blindness, as well as the idea that there are area specializations in the cortex. Many studies have shown that lesions in the areas commonly identified as the color center, such as V1, V2, and the V4-complex lead to achromatopsia. Cerebral achromatopsia occurs after injury to the lingual or fusiform gyrus, the areas associated with hV4. These injuries include physical trauma, stroke, and tumor growth. One of the primary initiatives to locating the color center in the visual cortex is to discover the cause and a possible treatment of cerebral achromatopsia.
The extent of the symptoms and the damage is different from person to person. If a person has complete achromatopsia, then their entire visual field is devoid of color. A person with dyschromatopsia, or incomplete achromtopsia, has similar symptoms to complete achromatopsia, but to a lesser degree. This can occur in people who had achromatopsia, but the brain recovered from the injury, restoring some color vision. The person may be able to see certain colors. However, there are many cases where there is no recovery. Finally, a person with hemiachromatopsia see half of their field of vision in color, and the other half in grey. The visual hemifield contralateral to a lesion in the lingual or fusiform gyrus is the one that appears grey, while the ipsilateral visual hemifield appears in color. The variance in symptoms emphasizes the need to understand the architecture of the color center in order to better diagnose and possible treat cerebral achromotopsia.
Read more about this topic: Colour Centre