Evolution of Central Pathways

Carr, Catherine E.

doi:10.1016/b978-0-12-809324-5.24168-0

Cited by 4 publications

(2 citation statements)

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“…Projections from the western rat snake basilar papilla entered the medulla where they bifurcate and terminate in two nonoverlapping nuclei, NA and NM, following the diapsid pattern (Carr, 2020; Walton et al., 2017). These auditory nerve projections were similar to those of lizards, although studies that measured postganglionic nerve fiber diameters from tract tracing material reported larger diameters in alligator lizards and geckos (Szpir et al., 1990; Tang et al., 2012).…”

Section: Discussionmentioning

confidence: 99%

Central projections of auditory nerve fibers in the western rat snake (Pantherophis obsoletus)

Han

Carr

2023

J of Comparative Neurology

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Despite the absence of tympanic middle ears, snakes can hear. They are thought to primarily detect substrate vibration via connections between the lower jaw and the inner ear. We used the western rat snake (Pantherophis obsoletus) to determine how vibration is processed in the brain. We measured vibration‐evoked potential recordings to reveal sensitivity to low‐frequency vibrations. We then used tract tracing combined with immunohistochemistry and Nissl staining to describe the central projections of the papillar branch of the VIIIth nerve. Applications of biotinylated dextran amine to the basilar papilla (homologous to the organ of Corti of mammals) labeled bouton‐like terminals in two first‐order cochlear nuclei, a rostrolateral nucleus angularis (NA) and a caudomedial nucleus magnocellularis (NM). NA formed a distinct dorsal eminence, consisted of heterogenous cell types, and was parvalbumin positive. NM was smaller and poorly separated from the surrounding vestibular nuclei. NM was distinguished by positive calbindin label and included fusiform and round cells. Thus, the atympanate western rat snake shares similar first‐order projections to tympanate reptiles. Auditory pathways may be used for detecting vibration, not only in snakes but also potentially in atympanate early tetrapods.

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Section: Discussionmentioning

confidence: 99%

Central projections of auditory nerve fibers in the western rat snake (Pantherophis obsoletus)

Han

Carr

2023

J of Comparative Neurology

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“…Despite such use, mammalian tympani and middle ears (Fritzsch et al., 2013; Holte, 1996; Thompson et al., 1979; Uchida et al., 2000) and the Drosophila antennal sound receiver (Austin, Thomas et al., 2023; Keder et al., 2020; Sharma et al., 2023) function well into old age. Age‐related structural changes occur in the mechanical components of middle ears (Carr, 2020; Ruah et al., 1991), but, if anything, these appear to be compensatory against any loss of function. The desert locust, however, has an age‐related decrease in tympanal displacement (Austin, Woodrow et al., 2023), which appears to be associated with age‐related sclerotization (hardening) of insect cuticle.…”

Section: Evolutionary Journey Of Hearing Organs Justification For Usi...mentioning

confidence: 99%

What can insects teach us about hearing loss?

Warren,

Eberl

2023

The Journal of Physiology

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Over the last three decades, insects have been utilized to provide a deep and fundamental understanding of many human diseases and disorders. Here, we present arguments for insects as models to understand general principles underlying hearing loss. Despite ∼600 million years since the last common ancestor of vertebrates and invertebrates, we share an overwhelming degree of genetic homology particularly with respect to auditory organ development and maintenance. Despite the anatomical differences between human and insect auditory organs, both share physiological principles of operation. We explain why these observations are expected and highlight areas in hearing loss research in which insects can provide insight. We start by briefly introducing the evolutionary journey of auditory organs, the reasons for using insect auditory organs for hearing loss research, and the tools and approaches available in insects. Then, the first half of the review focuses on auditory development and auditory disorders with a genetic cause. The second half analyses the physiological and genetic consequences of ageing and short‐ and long‐term changes as a result of noise exposure. We finish with complex age and noise interactions in auditory systems. In this review, we present some of the evidence and arguments to support the use of insects to study mechanisms and potential treatments for hearing loss in humans. Obviously, insects cannot fully substitute for all aspects of human auditory function and loss of function, although there are many important questions that can be addressed in an animal model for which there are important ethical, practical and experimental advantages. image

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