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Chapitre D'ouvrage Année : 2017

The Brains of Teleost Fishes

Philippe Vernier

Résumé

Teleost fishes, the largest group of craniates exhibit a tremendous diversity of shape and ways of life. Their brains display accordingly a large array of morphologies and functional differences from one species to another. Nevertheless, teleost brains are built according to the standard Bauplan or morphotype of the vertebrate brain, with well-identified regions homologous to that of the other vertebrates, from the forebrain to the hindbrain. However, the teleost brains also display many peculiarities, with no counterpart in other vertebrates, highlighting the undervalued complexity of these brains. A first major difference is the apparent eversion of the pallial hemispheres of teleosts, at odds with the evagination of the telencephalic hemispheres of the other vertebrate groups. The specific mode of development of the pallium in teleosts makes difficult the recognition of similarities with the pallial organization of other vertebrate group such as the tetrapods, with the notable exception of the hippocampus and pallial amygdalar domain. Similarly, to what extent the subpallial regions of teleost resemble that of the tetrapod basal ganglia await precise developmental, neurochemical and hodological data. Other divisions of the forebrain include the region of the optic recess and hypothalamus, which exhibit many peculiarities as compared to mammals, especially in the periventricular region. Then, basal diencephalon of teleosts is particularized by the presence of the sensory relays of the posterior tuberculum sending projection to the pallium, at odd with the thalamic inputs found in tetrapods. The mesencephalon is devoid of the major dopamine nuclei (substantia nigra and ventral tegmental area) controlling motivated behaviours, executive functions and sensorimotor programming, although such behaviours exist in teleosts as in the other vertebrates. Thus, the teleost brain is by no mean a simplified vertebrate brain, but the reflect of a huge diversity of functions and adaptations that develop over more than 300 millions years of evolution.
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Dates et versions

hal-04249292 , version 1 (19-10-2023)

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Philippe Vernier. The Brains of Teleost Fishes. Evolution of Nervous Systems (2nd edition), 1, Elsevier, pp.59-75, 2017, ⟨10.1016/B978-0-12-804042-3.00004-X⟩. ⟨hal-04249292⟩
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