A histoquantitative study of the striate cortex and lateral geniculate body in normal, blind and demented subjects

The amount of myelin in the outer band of Baillarger in the human visual cortex stained by Luxol Fast Blue MBS, has been measured in normal individuals of wide age range, in a group of blind and severely visually impaired but otherwise normal individuals and in a series of demented patients of the Alzheimer and multi-infarct type who were apparently visually normal. The amount of myelin is found to be significantly reduced in the blind and demented groups. Examination of the lateral geniculate body in the blind cases demonstrated slight reduction in neuron numbers and marked reduction in mean neuron diameter. Neuronal cytoplasmic ribonucleic acid, nucleolar volume and numbers of tetraploid glial nuclei in the blind or visually impaired cases were significantly reduced when compared with controls, indicating reduced function in these neurons. Similar results were obtained on examining this nucleus in Alzheimer and multi-infarct cases, suggesting that the visual pathways may be involved in these conditions. It is concluded that loss of myelin from the outer band of Baillarger occurs in association with reduced function of neurons in the lateral geniculate body.