PUBLICATION
Positive or negative feedback of optokinetic signals: degree of the misrouted optic flow determines system dynamics of human ocular motor behavior
- Authors
- Chen, C.C., Bockisch, C.J., Olasagasti, I., Weber, K.P., Straumann, D., Huang, M.Y.
- ID
- ZDB-PUB-140513-412
- Date
- 2014
- Source
- Investigative ophthalmology & visual science 55: 2297-306 (Journal)
- Registered Authors
- Huang, Melody Ying-Yu
- Keywords
- infantile nystagmus syndrome (INS), misrouting of optic fibers, optokinetic response (OKR), positive and negative feedback optokinetic systems, spontaneous eye oscillations
- MeSH Terms
-
- Adult
- Feedback, Sensory/physiology*
- Humans
- Middle Aged
- Nystagmus, Optokinetic/physiology*
- Nystagmus, Pathologic/physiopathology
- Optic Flow/physiology*
- Photic Stimulation
- Reference Values
- Video Recording
- Young Adult
- PubMed
- 24595381 Full text @ Invest. Ophthalmol. Vis. Sci.
Citation
Chen, C.C., Bockisch, C.J., Olasagasti, I., Weber, K.P., Straumann, D., Huang, M.Y. (2014) Positive or negative feedback of optokinetic signals: degree of the misrouted optic flow determines system dynamics of human ocular motor behavior. Investigative ophthalmology & visual science. 55:2297-306.
Abstract
Purpose The optokinetic system in healthy humans is a negative-feedback system that stabilizes gaze: slow-phase eye movements (i.e., the output signal) minimize retinal slip (i.e., the error signal). A positive-feedback optokinetic system may exist due to the misrouting of optic fibers. Previous studies have shown that, in a zebrafish mutant with a high degree of the misrouting, the optokinetic response (OKR) is reversed. As a result, slow-phase eye movements amplify retinal slip, forming a positive-feedback optokinetic loop. The positive-feedback optokinetic system cannot stabilize gaze, thus leading to spontaneous eye oscillations (SEOs). Because the misrouting in human patients (e.g., with a condition of albinism or achiasmia) is partial, both positive- and negative-feedback loops co-exist. How this co-existence affects human ocular motor behavior remains unclear.
Methods We presented a visual environment consisting of two stimuli in different parts of the visual field to healthy subjects. One mimicked positive-feedback optokinetic signals and the other preserved negative-feedback optokinetic signals. By changing the ratio and position of the visual field of these visual stimuli, various optic nerve misrouting patterns were simulated. Eye-movement responses to stationary and moving stimuli were measured and compared with computer simulations. The SEOs were correlated with the magnitude of the virtual positive-feedback optokinetic effect.
Results We found a correlation among the simulated misrouting, the corresponding OKR, and the SEOs in humans. The proportion of the simulated misrouting needed to be greater than 50% to reverse the OKR and at least greater than or equal to 70% to evoke SEOs. Once the SEOs were evoked, the magnitude positively correlated to the strength of the positive-feedback OKR.
Conclusions This study provides a mechanism of how the misrouting of optic fibers in humans could lead to SEOs, offering a possible explanation for a subtype of infantile nystagmus syndrome (INS).
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping