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Schlagwörter:
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Zusammenfassung:
We recorded from single cells in area V2 of cynomolgus monkeys using
standard acute recording techniques. After measuring each cell's
spatial and temporal properties, we performed several tests of its
chromatic properties using sinewave gratings modulated around a mean
gray background. Most cells behaved like neurons in area V1 and their
response was adequately described by a model that assumes a linear
combination of cone signals. Unlike in V1, we found a subpopulation of
cells whose activity was increased or inhibited by stimuli within a
narrow range of color combinations. No particular color directions
were preferentially represented. V2 cells showing color-specificity,
including cells showing narrow chromatic tuning, could be found in any
of the stripe compartments, as defined by cytochrome-oxidase (CO)
staining. An addition of chromatic contrast facilitated the responses
of most neurons to gratings with various luminance contrasts. Neurons
in all three CO-compartments gave a significant population response to
isoluminant gratings. Receptive fields properties of cells were
generally similar for luminance and chromatically defined stimuli. We
found only a small number of cells with a clearly identifiable
double-opponent receptive field organization. The similarity between
the chromatic tuning characteristics of individual color-specific
cells in area V2 and psychophysically observed higher order color
mechanisms suggests an important role for area V2 in the cortical
hierarchy for the processing of color signals.
