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Cortical mechanisms for afterimage formation: evidence from interocular grouping
Bo Dong1,2, Linus Holm3, Min Bao1
1CAS Key Laboratory of Behavioral Science, Institute of Psychology, Beijing 100101, P.R. China.
Scientific Reports
|January 24, 2017
Summary
Afterimage (AI) formation is not solely a retinal process. This study shows the cortex is directly involved in generating afterimage signals, challenging previous theories.
Area of Science:
- Neuroscience
- Visual Perception
- Ophthalmology
Background:
- The origin of afterimage (AI) formation, whether solely retinal or jointly retinal and cortical, is a long-standing debate.
- Recent theories suggest afterimages are exclusively generated in the retina, with later cortical modification.
Purpose of the Study:
- To investigate the role of the retina versus the cortex in afterimage (AI) generation.
- To test the hypothesis that afterimage signals originate exclusively in the retina.
Main Methods:
- Utilized the method of "indirect proof" with binocular rivalry.
- Presented dichoptic checkerboard patterns (horizontal and vertical gratings) to induce rivalry and assess percepts.
- Compared monocular percept frequency during afterimage (AI) presentation versus contrast-matched inductions.
Main Results:
- Higher contrast increased the frequency of monocular percepts during initial pattern presentation.
- Contrary to the retinal-only hypothesis, subjects reported significantly more fully coherent stripes during afterimages (AIs).
- This indicates reduced visual system sensitivity during AIs due to adaptation.
Conclusions:
- The findings contradict the notion that afterimage (AI) generation is exclusively a retinal process.
- Evidence suggests that cortical mechanisms play a direct role in the generation of afterimage signals, alongside retinal contributions.
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