Spatial scaling of end-stopped perceptive fields: differences in neural bases of end-zones, flanks and centers.
Length and width spatial interactions associated with a small test line centered on a rectangular background were measured at 0, 5 and 10 deg retinal eccentricities. Results indicated an elongated central region of summation with antagonistic flanks and end-zones comparable to earlier results [Yu, C. & Essock, E. A. (1996). Vision Research 36, 2883-2896]. The extent of the end-zones, flanks and centers (length and width) exhibited significantly different spatial scaling, which was steepest for the end-zones (E2 = 0.45 deg), less steep for the flanks (E2 = 0.77 deg) and least steep for the centers (E2 = 2.05 deg). Perceptive fields measured with concentric circular stimuli showed center and surround scaling equivalent to center and flank scaling, respectively, in line target experiments. These results suggest that: (1) psychophysical end-stopping and flank-inhibition reflect different underlying cortical neural processes; and (2) the spatial interactions apparent on the conventional Westheimer paradigm are partly governed by cortical factors.
Yu
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Department of Psychology, University of Louisville, KY 40292, USA.
Essock
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EA
D000328:Adult; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008297:Male; D009433:Neural Inhibition / Q000502:physiology; D011601:Psychophysics; D012684:Sensory Thresholds / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology; D014794:Visual Fields