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Organotopic organization of the primary Infrared Sensitive Nucleus (LTTD) in the western diamondback rattlesnake ( Crotalus atrox )
Author(s) -
Kohl Tobias,
Bothe Maximilian S.,
Luksch Harald,
Straka Hans,
Westhoff Guido
Publication year - 2014
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23644
Subject(s) - hindbrain , sensory system , anatomy , neuroscience , biology , nucleus , trigeminal nerve , central nervous system , axoplasmic transport , sensory neuron
ABSTRACT Pit vipers (Crotalinae) have a specific sensory system that detects infrared radiation with bilateral pit organs in the upper jaw. Each pit organ consists of a thin membrane, innervated by three trigeminal nerve branches that project to a specific nucleus in the dorsal hindbrain. The known topographic organization of infrared signals in the optic tectum prompted us to test the implementation of spatiotopically aligned sensory maps through hierarchical neuronal levels from the peripheral epithelium to the first central site in the hindbrain, the nucleus of the lateral descending trigeminal tract (LTTD). The spatial organization of the anatomical connections was revealed in a novel in vitro whole‐brain preparation of the western diamondback rattlesnake ( Crotalus atrox ) that allowed specific application of multiple neuronal tracers to identified pit‐organ‐supplying trigeminal nerve branches. After adequate survival times, the entire peripheral and central projections of fibers within the pit membrane and the LTTD became visible. This approach revealed a morphological partition of the pit membrane into three well‐defined sensory areas with largely separated innervations by the three main branches. The peripheral segregation of infrared afferents in the sensory epithelium was matched by a differential termination of the afferents within different areas of the LTTD, with little overlap. This result demonstrates a topographic organizational principle of the snake infrared system that is implemented by maintaining spatially aligned representations of environmental infrared cues on the sensory epithelium through specific neuronal projections at the level of the first central processing stage, comparable to the visual system. J. Comp. Neurol. 522:3943–3959, 2014. © 2014 Wiley Periodicals, Inc.