The responses of neurons in areas V1 (17) and V2
(18) of anesthetized and paralyzed rhesus monkeys and cats
were recorded while presenting a set of computer-generated
visual stimuli that varied in pattern, texture, luminance,
and contrast. We find that a class of extrastriate cortical
cells in cats and monkeys can signal the presence of boundaries
regardless of the cue or cues that define the boundaries.
These cue-invariant (CI) cells were rare in area V1 but
easily found in V2. CI cortical cells responded more strongly
to more salient boundaries regardless of the cue defining
the boundaries. Many CI cortical cells responded to illusory
contours and exhibited the same degree of orientation and
direction selectivity when tested with boundaries defined
by different cues. These cells have significant computational
power inherent in their receptive fields since they were
able to generalize across stimuli and integrate multiple
cues simultaneously in order to signal boundaries. Cells
in higher order cortical areas such as MT (Albright, 1992),
MST (Geesaman & Anderson, 1996), and IT (Sary et al.,
1993) have previously been reported to respond in a cue
invariant fashion. The present results suggest that the
ability to respond to boundaries in a cue-invariant manner
originates at relatively early stages of cortical processing.