THE DIFFERING EFFECTS OF DIFFERENT PARTS OF THE VISUAL FIELD UPON THE CHROMATOPHORE RESPONSES OF FISHES

1933 ◽  
Vol 65 (2) ◽  
pp. 266-282 ◽  
Author(s):  
FRANCIS B. SUMNER
Keyword(s):  
Visual Field ◽  
Different Parts

scholarly journals The visual perception of movement by toads

1944 ◽  
Vol 132 (868) ◽  
pp. 291-307 ◽  
Keyword(s):  
Visual Field ◽  
Visual Perception ◽  
Ample Evidence ◽  
Stationary Objects ◽  
Different Parts

The feeding reaction of toads has been shown by experiment to be dependent on the visual perception of movement. The influence of the visual field on the snapping reaction has been investigated with an apparatus which allowed the object, subject and parts of the visual field to be moved independently of each other. Ample evidence for kinematoscopic sensation of movement was found at speeds varying from 27 to 5 pictures per sec. Evidence is brought forward to prove that toads are able to recognize stationary objects and even to discriminate different parts of them.

scholarly journals Spectral tuning by opsin coexpression in retinal regions that view different parts of the visual field

2014 ◽  
Vol 281 (1797) ◽  
pp. 20141980 ◽  
Author(s):  
Brian E. Dalton ◽  
Ellis R. Loew ◽  
Thomas W. Cronin ◽  
Karen L. Carleton
Keyword(s):  
Visual Field ◽  
Visual Pigment ◽  
Cichlid Fish ◽  
Visual Pigments ◽  
Colour Discrimination ◽  
Spectral Tuning ◽  
Trade Off ◽  
Opsin Genes ◽  
First Time ◽  
Different Parts

Vision frequently mediates critical behaviours, and photoreceptors must respond to the light available to accomplish these tasks. Most photoreceptors are thought to contain a single visual pigment, an opsin protein bound to a chromophore, which together determine spectral sensitivity. Mechanisms of spectral tuning include altering the opsin, changing the chromophore and incorporating pre-receptor filtering. A few exceptions to the use of a single visual pigment have been documented in which a single mature photoreceptor coexpresses opsins that form spectrally distinct visual pigments, and in these exceptions the functional significance of coexpression is unclear. Here we document for the first time photoreceptors coexpressing spectrally distinct opsin genes in a manner that tunes sensitivity to the light environment. Photoreceptors of the cichlid fish, Metriaclima zebra , mix different pairs of opsins in retinal regions that view distinct backgrounds. The mixing of visual pigments increases absorbance of the corresponding background, potentially aiding the detection of dark objects. Thus, opsin coexpression may be a novel mechanism of spectral tuning that could be useful for detecting prey, predators and mates. However, our calculations show that coexpression of some opsins can hinder colour discrimination, creating a trade-off between visual functions.

Further Studies of the Sea-Finding Mechanism in Green Turtle Hatchlings

Behaviour ◽  
1974 ◽  
Vol 51 (3-4) ◽  
pp. 195-208 ◽  
Author(s):  
Sara J. Shettleworth ◽  
N. Osovsky
Keyword(s):  
Visual Field ◽  
Green Turtle ◽  
Chelonia Mydas ◽  
The Other ◽  
Green Turtles ◽  
Visual Inputs ◽  
Simultaneous Comparison ◽  
Temporal Field ◽  
Different Parts ◽  
Made In

AbstractFurther studies were made of the simultaneous comparison mechanism used by hatchling green turtles, Chelonia mydas, in sea-finding behaviour. The aim was to learn if visual inputs from different directions, stimulating different parts of the retina, had the same effects on orientation. To do this goggles were designed that permitted occlusion of parts of the visual field. Wearing goggles did not in itself affect orientation. When the nasal visual field for one eye and the temporal field for the other eye were covered, turtles circled consistently in the direction of the eye with the nasal occlusion. The total numbers of circles made in a given time by such turtles were not significantly different from those made by animals with simple unilateral blindfolds. Covering the temporal field of one eye resulted in some, though not all, turtles turning contralateral to that eye, provided the other eye was totally covered. On the whole the data were consistent with the idea that inputs in the nasal field are associated with contralateral turning and those in the temporal field with ipsilateral turning. Some complications to this interpretation are also discussed. However, the results demonstrate unequivocally that inputs from different directions contribute differently to sea-finding orientation of green turtles.

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