Polarization vision in goldfish: do they startle to polarized light looms?

OTERO CORONEL, SANTIAGO; BERÓN DE ASTRADA, MARTÍN; MEDAN, VIOLETA

Buenos ASires

Congreso; 2nd Congress of the Federation of Latin-American and Caribbean Societies for Neuroscience (FALAN); 2016

Federation of Latin-American and Caribbean Societies for Neuroscience (FALAN)

Aquatic environments are rich in polarized light patterns,creating a background polarization field against whichobjects diffusing or differentially reflecting polarized lightcan be viewed. To animals with a visual system sensitive topolarized light such as goldfish, Carassius auratus, these cuescould provide valuable information about its environmentand be used for navigation and object detection. To testto which extent polarization sensitivity is behaviorallyfunctional for goldfish, we recorded their startle response(C-start) probability in response to an expanding disc(loom) where the background was linearly polarized andthe loom was elliptically polarized. Goldfish startled to apolarized loom although with a smaller probability (25%startled, N=24) and longer latency (mean ± SD: 60±12 msafter the end of loom) than when confronted with a blackover-white control loom (100% startled, 79 ± 33 ms beforethe end of loom, N=14). Different neural processing and/orlower saliency of polarized looms could be responsible forthe lower probability and longer response latency. Usingnon-polarized looms we tested if decreasing the contrastratio (saliency) between the stimulus and the backgroundreduced the response probability and increased latencyof the response. Results show that progressively smallercontrast ratios have a smaller response probability andlonger latency, although it never reaches the valuesobserved with polarized looms.