Perhaps the most 
esthetically pleasing 
neurophysiological 
demonstration of corpus-
callosum function came from 
the work of Giovanni Berlucchi 
and Giacomo Rizzolatti in Pisa 
in 1968. Having cut the optic 
chiasm along the midline, they 
made recordings from area 17, 
close to the 17-18 border on the 
right side, and looked for cells 
that could be driven 
binocularly. Obviously any 
binocular cell in the visual 
cortex on the right side must 
receive input from the right eye 
directly (via the geniculate) and 
from the left eye by way of the 
left hemisphere and corpus 
callosum. Each binocular 
receptive field spanned the 
vertical midline, with the part 
to the left responding to the 
right eye and the part to the 
right responding to the left eye. 
Other properties, including 
orientation selectivity, were 
identical, as shown in the 
illustration to the left.

This experiment by Berlucchi 
and Rizzolatti beautifully 
illustrates not only the 
function of the visual part of 
the callosum but also the high 
specificity of its connections 
between cells of like 
orientation and bordering 
receptive fields. Berlucchi and 
Rizzolatti cut the chiasm of a 
cat in the midline, so that the 
left eye supplies only the left 
hemisphere, with information 
coming solely from the right 
field of vision. Similarly, the 
right eye supplies only the right 
hemisphere, with information 
from the left visual field. After 
making the incision, they 
recorded from a cell whose 
receptive field would normally 
overlap the vertical midline. 
They found that such a cell's 
receptive field is split 
vertically, with the right part 
supplied through the left eye 
and the left part through the 
right eye.