The twinkle aftereffect is pre-cortical and is independent of filling-in


Crossland MD, Bex PJ. The twinkle aftereffect is pre-cortical and is independent of filling-in. Journal of Vision [Internet]. 2008;8 :13 1–10.


A real or artificial scotoma within a dynamic noise field fills in within a few seconds. When the dynamic noise is replaced with a homogenous field, a twinkling after effect ({TwAE)} is induced exclusively in the location of the former scotoma. We are employing the appearance of the {TwAE} to perform rapid perimetry in patients with retinal scotomas. To analyze the loci within the visual system and the mechanisms of filling-in and the {TwAE}, we examined their orientation tuning, inter-ocular transfer, and threshold versus contrast functions by measuring contrast detection thresholds for stimuli presented in areas that were filled-in or contained the {TwAE.} For filling-in, detection thresholds were narrowly tuned for orientation, transferred interocularly, and rose monotonically with the contrast of a surround pattern. These results indicate that surround suppression and filling-in involve inhibitory processes originating at cortical stages of visual processing. Threshold versus contrast functions were weakly dipper-shaped for the {TwAE}, did not transfer inter-ocularly, and were not tuned for orientation. These results indicate that the {TwAE} involves additive noise that is pre-cortical in origin and that it is distinct from filling-in.