Direction selectivity and orientation selectivity
were examined in the direction-selective (DS) and orientation-
selective (OS) ganglion cells in the rabbit retina. Spike
activities were recorded in vivo using tungsten-in-glass
electrodes. Three types of visual stimuli (flashing slit,
moving edges behind a slit, and whole-field drifting gratings)
were used to distinguish these attributes. Fourier analysis
was performed on data obtained using drifting gratings
as proposed by Worgotter and Eysel (1987). Results from
both angular and Fourier (polar angle frequency) domains
were consistent. DS cells had strong directional components
and varying strength of orientational components; they
also had intact inhibitory surrounds. The phase of the
biased orientation did not have a consistent relationship
with the preferred direction. OS cells had predominant
orientational components and very weak directional components.
We conclude that the orientation bias does not contribute
to the generation of direction selectivity, and that the
mechanism of this bias of DS cells is rather different
from the mechanism that generates orientation selectivity
in rabbit OS cells. There are indications that it is similar
to the mechanism shown to cause orientation bias in cat
concentric cells.