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Threshold and chromatic sensitivity changes in fish cone horizontal cells following prolonged darkness
S C Mangel1, W H Baldridge, R Weiler
1Marine Biological Laboratory, Woods Hole, MA.
Brain Research
|October 3, 1994
Summary
Prolonged darkness alters teleost retinal cells. Cone horizontal cell responses become slow and sensitive to rod input, but recover with light exposure.
Area of Science:
- Neuroscience
- Retinal Physiology
- Visual System Research
Background:
- L-type cone horizontal cells are crucial for visual processing in teleost retinas.
- Understanding their response dynamics under different light conditions is vital for visual neuroscience.
Purpose of the Study:
- To investigate the functional changes in L-type cone horizontal cells after prolonged darkness.
- To determine the impact of dark adaptation on cellular responses and spectral sensitivity.
Main Methods:
- Intact, isolated white perch retinas were superfused in complete darkness for over 90 minutes.
- Horizontal cells were impaled and recorded without light stimulation.
- Responses to dim and bright full-field stimuli and spectral sensitivity were analyzed.
Main Results:
- Following darkness, light responses were slow, small in amplitude, and prolonged.
- Absolute threshold decreased by 2 log units, with increased sensitivity to shorter wavelengths.
- Subsequent bright light stimulation led to transient, larger amplitude responses and normalized thresholds.
Conclusions:
- Prolonged darkness reduces cone input to horizontal cells, suggesting the presence of rod input.
- Light sensitization rapidly restores typical L-type cone horizontal cell function.