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Connectivity and ultrastructure of dopaminergic innervation of the inner ear and auditory efferent system of a vocal fish
Author(s) -
Perelmuter Jonathan T.,
Forlano Paul M.
Publication year - 2017
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.24177
Subject(s) - efferent , saccule , biology , hindbrain , neuroscience , auditory system , cochlear nucleus , superior olivary complex , efferent neuron , vertebrate , anatomy , nucleus , inner ear , central nervous system , biochemistry , gene , afferent
Dopamine (DA) is a conserved modulator of vertebrate neural circuitry, yet our knowledge of its role in peripheral auditory processing is limited to mammals. The present study combines immunohistochemistry, neural tract tracing, and electron microscopy to investigate the origin and synaptic characteristics of DA fibers innervating the inner ear and the hindbrain auditory efferent nucleus in the plainfin midshipman, a vocal fish that relies upon the detection of mate calls for reproductive success. We identify a DA cell group in the diencephalon as a common source for innervation of both the hindbrain auditory efferent nucleus and saccule, the main hearing endorgan of the inner ear. We show that DA terminals in the saccule contain vesicles but transmitter release appears paracrine in nature, due to the apparent lack of synaptic contacts. In contrast, in the hindbrain, DA terminals form traditional synaptic contacts with auditory efferent neuronal cell bodies and dendrites, as well as unlabeled axon terminals, which, in turn, form inhibitory‐like synapses on auditory efferent somata. Our results suggest a distinct functional role for brain‐derived DA in the direct and indirect modulation of the peripheral auditory system of a vocal nonmammalian vertebrate.