Visual Neuroscience

Research Articles

Cue-dependent deficits in grating orientation discrimination after V4 lesions in macaques

Peter De Weerda1, Robert Desimonea2 and Leslie G. Ungerleidera1

a1 Laboratory of Psychology and Psychopathology, NIMH, Bethesda

a2 Laboratory of Neuropsychology, NIMH, Bethesda


To examine the role of visual area V4 in pattern vision, we tested two monkeys with lesions of V4 on tasks that required them to discriminate the orientation of contours defined by several different cues. The cues used to separate the contours from their background included luminance, color, motion, and texture, as well as phase-shifted abutting gratings that created an “illusory” contour. The monkeys were trained to maintain fixation on a fixation target while discriminating extrafoveal stimuli, which were located in either a normal control quadrant of the visual field or in a quadrant affected by a lesion of area V4 in one hemisphere. Comparing performance in the two quadrants, we found significant deficits for contours defined by texture and for the illusory contour, but smaller or no deficits for motion-, color-, and luminance-defined contours. The data suggest a specific role of V4 in the perception of illusory contours and contours defined by texture.

(Received July 27 1995)

(Accepted October 13 1995)


Reprint requests to: Leslie G. Ungerleider, Laboratory of Psychology and Psychopathology, NIMH, N1H, Bldg. 49, Rm. 1B80, 49 Convent Dr. MSC 4415, Bethesda, MD 20892-4415, USA