Receptive field discontinuities in the achiasmatic mutant. These data are taken from case M1. Double asterisk marks a lesion along P6 that is also marked in Fig. In contrast, more rostral penetrations initially traversed layer A and then passed into A1. The progression of fields from high to low elevation is normal, and is caused by the dorsoventral orientation of geniculate layers.
Small inset is a schematic plan view of the four electrode penetrations.
Paralytic agents were not used. Heart rate was monitored. The eyes were protected with contact lenses, stabilized by suturing to eye rings, and focused on a tangent screen 57 cm from the dogs' eyes. A craniotomy was made over the thalamus. The brain, eyes, and optic nerves were dissected free from the cranium.