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THE FLICKER RESPONSE CONTOUR FOR THE ISOPOD ASELLUS
W J Crozier1, E Wolf, G Zerrahn-Wolf
1Biological Laboratories, Harvard University, Cambridge.
The Journal of General Physiology
|October 30, 2009
Summary
The flicker response contour in isopods (Asellus) follows a simple probability integral, unlike arthropods with complex eyes. This finding confirms theories on photoreception and highlights a shared neural organization feature across diverse invertebrates.
Area of Science:
- Comparative physiology
- Neuroscience
- Visual perception
Background:
- Flicker response contours in arthropods often show asymmetrical curves.
- This distortion has been attributed to mechanical factors in photoreception, particularly in species with large, convex eyes.
Purpose of the Study:
- To characterize the flicker response contour of the isopod Asellus.
- To compare the Asellus contour with those of other arthropods and vertebrates.
- To investigate the underlying factors influencing visual system organization.
Main Methods:
- Experimental determination of flicker response contours.
- Analysis of the relationship between flicker fusion frequency (F) and log intensity (log I).
- Comparison of mathematical models describing the flicker response.
Main Results:
- The flicker response contour for Asellus is a simple probability integral, differing from distorted curves in arthropods like Apis and Anax.
- This simple contour supports the hypothesis that mechanical conditions in photoreception cause distortion in other arthropods.
- The relative dispersion of intensity thresholds is remarkably consistent across bee, dragonfly nymph, and isopod visual systems.
Conclusions:
- The simple flicker response contour in Asellus is attributed to its eye structure, lacking the mechanical constraints seen in arthropods with complex eyes.
- The probability integral model provides a superior fit for uncomplicated flicker response contours.
- A conserved neural organization feature, responsible for consistent intensity threshold dispersion, exists in diverse arthropods but contrasts with vertebrate visual system diversity.
