Ferrier Lecture - The organization of the visual cortex in man

In this lecture, which was founded to commemorate the pioneer work of Sir David Ferrier on cerebral localization, I intend to deal with a subject in which he was particularly interested, that is the cortical representation of vision. Ferrier’s interest was at once excited by the discovery of Fritsch & Hitzig (1870) that certain portions of the surface of the forebrain are excitable, and he immediately adopted this new method of electrical stimulation to map out those areas from which movements can be produced. The results of his investigations on the motor cortex are well known, but he also discovered that movements could be elicited from other regions which he did not regard as primarily motor, including deviations of the eyes on stimulation of the angular gyrus on the lateral surface of the parietal lobe. He interpreted these movements as motor responses to ‘excitation of subjective visual sensations’ by the stimulus, and he therefore assumed that this region contained the primary visual centres, that is the centres through which retinal impressions excite visual perception. A series of experiments on monkeys which he reported in the Croonian Lecture of 1875 appeared to sup­port this conclusion, for he found that destruction of one angular gyrus caused blindness of the opposite eye, which was not, however, permanent if the other angular gyrus was intact (Fig. 1). Ablation of both angular gyri appeared to cause complete and permanent loss of vision. He failed to detect any disturbance of sight when one occipital lobe only was injured, provided the lesion did not extend forwards to the angular gyrus.