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Reduced performance of prey targeting in pit vipers with contralaterally occluded infrared and visual senses.

Chen Q, Deng H, Brauth SE, Ding L, Tang Y - PLoS ONE (2012)

Bottom Line: Both visual and infrared (IR) senses are utilized in prey targeting by pit vipers.Visual and IR inputs project to the contralateral optic tectum where they activate both multimodal and bimodal neurons.Performance was significantly poorer when only a single eye or pit was available.

View Article: PubMed Central - PubMed

Affiliation: Department of Herpetology, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China.

ABSTRACT
Both visual and infrared (IR) senses are utilized in prey targeting by pit vipers. Visual and IR inputs project to the contralateral optic tectum where they activate both multimodal and bimodal neurons. A series of ocular and pit organ occlusion experiments using the short-tailed pit viper (Gloydius brevicaudus) were conducted to investigate the role of visual and IR information during prey targeting. Compared with unoccluded controls, snakes with either both eyes or pit organs occluded performed more poorly in hunting prey although such subjects still captured prey on 75% of trials. Subjects with one eye and one pit occluded on the same side of the face performed as well as those with bilateral occlusion although these subjects showed a significant targeting angle bias toward the unoccluded side. Performance was significantly poorer when only a single eye or pit was available. Interestingly, when one eye and one pit organ were occluded on opposite sides of the face, performance was poorest, the snakes striking prey on no more than half the trials. These results indicate that, visual and infrared information are both effective in prey targeting in this species, although interference between the two modalities occurs if visual and IR information is restricted to opposite sides of the brain.

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Related in: MedlinePlus

Positions of pits and eyes and demonstrate of sensory occlusion.A: Photograph of the head of Gloydius brevicaudus showing the location of the lateral facial pit organ between the ipsilateral eye and nostril. B: Photograph of the rostral view of the head of G. brevicaudus showing both eyes and facial pits. C: A photograph of an experimental subject illustrating left side sensory occlusion (see Materials and Methods for explanation).
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pone-0034989-g004: Positions of pits and eyes and demonstrate of sensory occlusion.A: Photograph of the head of Gloydius brevicaudus showing the location of the lateral facial pit organ between the ipsilateral eye and nostril. B: Photograph of the rostral view of the head of G. brevicaudus showing both eyes and facial pits. C: A photograph of an experimental subject illustrating left side sensory occlusion (see Materials and Methods for explanation).

Mentions: The short-tailed pit viper, Gloydius brevicaudus (Viperidae: Crotalinae; Fig. 4), was selected for study because it is an effective hunter under a variety of conditions including both in light and darkness. Gloydius is a relatively small pit viper, easy to control in the experimental arena, remains tranquil in the absence of stimulation, and displays prey orientation and capture behaviors that can be quantified easily under laboratory conditions. Subjects used in this study were collected from Anhui and Hubei provinces in China. All animal work of this paper has been conducted according to relevant national and international guidelines. All animal care and experimental procedures were approved by the Chengdu Institute of Biology Animal Care and Use Committee. No animal suffered unnecessary pain in experiments. Each snake was kept in a home cage, a plastic terrarium (50×35×20 cm), the floor of which was covered with old newspaper (i.e. lacking the smell of printer’s ink), at temperatures between 24–26°C. Water was available ad libitum. Prior to the experiment, snakes were fed live mice once every two weeks. For the experiments, 10 subjects with reliable propensities to attack prey were selected (total length of 43–55 cm; weight 45.8–96.6 g; male:female = 5∶5), based on prior observations of their successful predatory behavior. Prey consisted of mice (Mus musculus) of both sexes which were used for both normal feeding of the snakes and for the experiments. Suitable mice were chosen according to the body size of each snake (i.e. the width of the head of the mouse was not substantially larger than the size of the head of the snake). The experimental trials were conducted according to the snakes’ normal feeding schedule. In other words, mice used in the targeting trials were part of the normal feeding regimen for the experimental subjects.


Reduced performance of prey targeting in pit vipers with contralaterally occluded infrared and visual senses.

Chen Q, Deng H, Brauth SE, Ding L, Tang Y - PLoS ONE (2012)

Positions of pits and eyes and demonstrate of sensory occlusion.A: Photograph of the head of Gloydius brevicaudus showing the location of the lateral facial pit organ between the ipsilateral eye and nostril. B: Photograph of the rostral view of the head of G. brevicaudus showing both eyes and facial pits. C: A photograph of an experimental subject illustrating left side sensory occlusion (see Materials and Methods for explanation).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351397&req=5

pone-0034989-g004: Positions of pits and eyes and demonstrate of sensory occlusion.A: Photograph of the head of Gloydius brevicaudus showing the location of the lateral facial pit organ between the ipsilateral eye and nostril. B: Photograph of the rostral view of the head of G. brevicaudus showing both eyes and facial pits. C: A photograph of an experimental subject illustrating left side sensory occlusion (see Materials and Methods for explanation).
Mentions: The short-tailed pit viper, Gloydius brevicaudus (Viperidae: Crotalinae; Fig. 4), was selected for study because it is an effective hunter under a variety of conditions including both in light and darkness. Gloydius is a relatively small pit viper, easy to control in the experimental arena, remains tranquil in the absence of stimulation, and displays prey orientation and capture behaviors that can be quantified easily under laboratory conditions. Subjects used in this study were collected from Anhui and Hubei provinces in China. All animal work of this paper has been conducted according to relevant national and international guidelines. All animal care and experimental procedures were approved by the Chengdu Institute of Biology Animal Care and Use Committee. No animal suffered unnecessary pain in experiments. Each snake was kept in a home cage, a plastic terrarium (50×35×20 cm), the floor of which was covered with old newspaper (i.e. lacking the smell of printer’s ink), at temperatures between 24–26°C. Water was available ad libitum. Prior to the experiment, snakes were fed live mice once every two weeks. For the experiments, 10 subjects with reliable propensities to attack prey were selected (total length of 43–55 cm; weight 45.8–96.6 g; male:female = 5∶5), based on prior observations of their successful predatory behavior. Prey consisted of mice (Mus musculus) of both sexes which were used for both normal feeding of the snakes and for the experiments. Suitable mice were chosen according to the body size of each snake (i.e. the width of the head of the mouse was not substantially larger than the size of the head of the snake). The experimental trials were conducted according to the snakes’ normal feeding schedule. In other words, mice used in the targeting trials were part of the normal feeding regimen for the experimental subjects.

Bottom Line: Both visual and infrared (IR) senses are utilized in prey targeting by pit vipers.Visual and IR inputs project to the contralateral optic tectum where they activate both multimodal and bimodal neurons.Performance was significantly poorer when only a single eye or pit was available.

View Article: PubMed Central - PubMed

Affiliation: Department of Herpetology, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China.

ABSTRACT
Both visual and infrared (IR) senses are utilized in prey targeting by pit vipers. Visual and IR inputs project to the contralateral optic tectum where they activate both multimodal and bimodal neurons. A series of ocular and pit organ occlusion experiments using the short-tailed pit viper (Gloydius brevicaudus) were conducted to investigate the role of visual and IR information during prey targeting. Compared with unoccluded controls, snakes with either both eyes or pit organs occluded performed more poorly in hunting prey although such subjects still captured prey on 75% of trials. Subjects with one eye and one pit occluded on the same side of the face performed as well as those with bilateral occlusion although these subjects showed a significant targeting angle bias toward the unoccluded side. Performance was significantly poorer when only a single eye or pit was available. Interestingly, when one eye and one pit organ were occluded on opposite sides of the face, performance was poorest, the snakes striking prey on no more than half the trials. These results indicate that, visual and infrared information are both effective in prey targeting in this species, although interference between the two modalities occurs if visual and IR information is restricted to opposite sides of the brain.

Show MeSH
Related in: MedlinePlus