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Ocular Kinematics Measured by In Vitro Stimulation of the Cranial Nerves in the Turtle
Published on: June 2, 2018
Consensual pupillary light response in the red-eared slider turtle (Trachemys scripta elegans).
James R Dearworth1, Grayson O Sipe, Lori J Cooper
1Department of Biology and Neuroscience Program, 311 Kunkel Hall, Lafayette College, Easton, PA 18042, United States. dearworj@lafayette.edu
Vision Research
|January 19, 2010
Summary
Turtles exhibit a consensual pupillary light response (cPLR), where stimulating one eye causes constriction in both. This cPLR is present but weaker than the direct pupillary light response (dPLR).
Area of Science:
- Comparative physiology
- Ophthalmology
- Neuroscience
Background:
- The pupillary light reflex is a fundamental visual response.
- Consensual pupillary light response (cPLR) is well-documented in mammals but less understood in reptiles.
Purpose of the Study:
- To investigate the presence and characteristics of a consensual pupillary light response (cPLR) in turtles.
- To compare the cPLR with the direct pupillary light response (dPLR) in the same subjects.
Main Methods:
- One eye of the turtle was illuminated with varying light intensities while the other remained in darkness.
- Pupil diameter changes were measured in both eyes.
- Mydriatic drugs were applied to assess their effect on cPLR and dPLR.
- Time constants of the responses were analyzed.
Main Results:
- Illuminating one eye caused significant pupil constriction in the directly stimulated eye (dPLR, ~31%) and a lesser constriction in the contralateral, non-illuminated eye (cPLR, ~11%).
- The ratio of cPLR to dPLR was approximately 0.35.
- Drug application affected dPLR more significantly than cPLR, further supporting the presence of a cPLR.
- Time constants for cPLR were comparable to, though generally shorter than, those for dPLR.
Conclusions:
- Turtles possess a consensual pupillary light response (cPLR).
- The cPLR in turtles is weaker than the direct pupillary light response (dPLR).
- These findings contribute to understanding reptilian visual neurophysiology.
