Hermann Munk1839–1912

Chiasmal crossing

Munk pursued the pathways from the eyes to the brain and provided confirmation of the speculations of the errant oculist John Taylor. Disputes about partial decussation at the optic chiasm had raged in the century and a half that separated the two but Munk’s painstaking dissections and beautiful illustrations established the routes taken from eye to brain. He is shown in one of his figures. Munk went on to examine the visual cortical functions in greater detail and in so doing crossed swords with Ferrier. Munk found that cortical lesions in the visual areas produced two types of blindness which he called psychic and cortical. Psychic blindness resulted in the animals (dogs and monkeys) behaving appropriately to objects (by avoiding collision with them, etc) but showing no evidence of recognising what they were. Cortical blindness, on the other hand, reflected total absence of vision, and it typically followed complete removal of the primary visual cortex.