1. It has been reported that in the cat only a specialized group of re
tinal ganglion cells constituting similar to 1% of the overall populat
ion are direction sensitive. Two major groups of retinal ganglion cell
s, the X and Y cells, have been reported not to be sensitive to the di
rection of stimulus motion. 2. We recorded action potentials of retina
l ganglion cells intraocularly. We studied quantitatively the visual r
esponses elicited by drifting sinusoidal gratings of various spatial f
requencies, bars, and spots. 3. The results confirm previous reports t
hat most cat retinal ganglion cells exhibit orientation biases when te
sted with gratings of relatively high spatial frequency. 4. Additional
ly, we find that 22% of X and 34% of Y type retinal ganglion cells exh
ibit direction biases. Overall, Y cells displayed significantly strong
er direction biases than did X cells. 5. In general, direction biases
are dearest when the test gratings are of relatively low spatial frequ
ency. 6. The direction biases of X and Y cells subserving the central
15 degrees of retina were weaker than those of cells subserving more p
eripheral regions. 7. The direction-biased responses of cat ganglion c
ells were similar to those of X and Y type relay cells in the cat dors
al lateral geniculate nucleus (LGNd). Thus we suggest that the directi
on biases of LGNd cells are a reflection of their retinal inputs.