Most amazing was the contrast 
between the machine-gun 
discharge when the orientation 
of the stimulus was just right 
and the utter lack of a response 
if we changed the orientation 
or simply shined a bright 
flashlight into the cat's eyes.

Responses of one of the first 
orientation-specific cells 
Torsten Wiesel and I recorded, 
from a cat striate cortex in 
1958. This cell not only 
responds exclusively to a 
moving slit in an eleven o'clock 
orientation but also responds to 
movement right and up, but 
hardly at all to movement left 
and down.

    The discovery was just the 
beginning, and for some time 
we were very confused because, 
as luck would have it, the cell 
was of a type that we came later 
to call complex, and it lay two 
stages beyond the initial, 
center-surround cortical stage. 
Although complex cells are the 
commonest type in the striate 
cortex, they are hard to 
comprehend if you haven't seen 
the intervening type.