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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

Schematic diagram of the two imaging sensory circuits.Schematic diagram of the snake brain (anterior is up and posterior is down) illustrating visual (blue) and IR (red) pathways showing convergence of visual (blue) and IR (red) inputs in the contralateral tectum. Abbreviations: LTTD, nucleus of the lateral descending trigeminal tract; RC, nucleus reticularis caloris; TeO, optic tectum. The arrow interconnecting the left and right optic tectums represents the tectal commissure and the filled triangle in the tecta represents the tectal bimodal neuronal population (see text).
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pone-0034989-g003: Schematic diagram of the two imaging sensory circuits.Schematic diagram of the snake brain (anterior is up and posterior is down) illustrating visual (blue) and IR (red) pathways showing convergence of visual (blue) and IR (red) inputs in the contralateral tectum. Abbreviations: LTTD, nucleus of the lateral descending trigeminal tract; RC, nucleus reticularis caloris; TeO, optic tectum. The arrow interconnecting the left and right optic tectums represents the tectal commissure and the filled triangle in the tecta represents the tectal bimodal neuronal population (see text).

Mentions: Neuroanatomical and neurophysiological studies have shown that both visual and IR inputs converge on bimodal neurons in the optic tectum of pit vipers [10], [14], [15], [16] as summarized in Figure 3. These studies show that inputs derived from both sensory modalities form similar spatiotopic maps supporting the idea that direct interactions between them occur at this level of the snake brain [13], [15] consistent with the idea that the two sensory systems can compensate for one another or act synergistically [16]. Convergence of these tectal pathways may explain our observations that prey targeting accuracy for the ipsilateral occluded trials showed no obvious differences with the trials in which either eyes or pits were occluded although the strike angles were biased to the open sensory sides. These results are consistent with anatomical and physiological studies indicating that information from both visual and IR sensors are integrated in the ipsilateral tectum. It is also possible that the integration of visual and IR inputs may occur within the brainstem nucleus isthmi of pit vipers insofar as studies in barn owls indicate that this structure is not only a visual processor, but also codes auditory information in a spatiotopic manner [20]. Additional physiological studies are needed to evaluate the role of the nucleus isthmi in pit vipers.


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)

Schematic diagram of the two imaging sensory circuits.Schematic diagram of the snake brain (anterior is up and posterior is down) illustrating visual (blue) and IR (red) pathways showing convergence of visual (blue) and IR (red) inputs in the contralateral tectum. Abbreviations: LTTD, nucleus of the lateral descending trigeminal tract; RC, nucleus reticularis caloris; TeO, optic tectum. The arrow interconnecting the left and right optic tectums represents the tectal commissure and the filled triangle in the tecta represents the tectal bimodal neuronal population (see text).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0034989-g003: Schematic diagram of the two imaging sensory circuits.Schematic diagram of the snake brain (anterior is up and posterior is down) illustrating visual (blue) and IR (red) pathways showing convergence of visual (blue) and IR (red) inputs in the contralateral tectum. Abbreviations: LTTD, nucleus of the lateral descending trigeminal tract; RC, nucleus reticularis caloris; TeO, optic tectum. The arrow interconnecting the left and right optic tectums represents the tectal commissure and the filled triangle in the tecta represents the tectal bimodal neuronal population (see text).
Mentions: Neuroanatomical and neurophysiological studies have shown that both visual and IR inputs converge on bimodal neurons in the optic tectum of pit vipers [10], [14], [15], [16] as summarized in Figure 3. These studies show that inputs derived from both sensory modalities form similar spatiotopic maps supporting the idea that direct interactions between them occur at this level of the snake brain [13], [15] consistent with the idea that the two sensory systems can compensate for one another or act synergistically [16]. Convergence of these tectal pathways may explain our observations that prey targeting accuracy for the ipsilateral occluded trials showed no obvious differences with the trials in which either eyes or pits were occluded although the strike angles were biased to the open sensory sides. These results are consistent with anatomical and physiological studies indicating that information from both visual and IR sensors are integrated in the ipsilateral tectum. It is also possible that the integration of visual and IR inputs may occur within the brainstem nucleus isthmi of pit vipers insofar as studies in barn owls indicate that this structure is not only a visual processor, but also codes auditory information in a spatiotopic manner [20]. Additional physiological studies are needed to evaluate the role of the nucleus isthmi in pit vipers.

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