Abstract
The sense of taste, although a relatively undistinguished sensory modality in most mammals, is a highly developed sense in many fishes, e.g., catfish, gadids, and carps including goldfish. In these species, the amount of neural tissue devoted to this modality may approach 20% of the entire brain mass, reflecting an enormous number of taste buds scattered across the external surface of the animal as well as within the oral cavity. The primary sensory nuclei for taste form a longitudinal column of nuclei along the dorsomedial surface of the medulla. Within this column of gustatory nuclei, the sensory system is represented as a fine-grain somatotopic map, with external body parts being represented rostrally within the column, and oropharyngeal surfaces being represented caudally. Goldfish have a specialization of the oral cavity, the palatal organ, which enables them to sort food particles from particulate substrate material such as gravel. The palatal organ taste information reaches the large, vagal lobe with a complex laminar and columnar organization. This lobe also supports a radially-organized reflex system which activates the musculature of the palatal organ to effect the sorting operation. The stereotyped, laminated structure of this system in goldfish has facilitated studies of the circuitry and neurotransmitter systems underlying the goldfish’s ability to sort food from stones.
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Acknowledgments
The author thanks the many collaborators and colleagues whose studies contributed to understanding the vagal lobe. Several of the summary diagrams in this work were adapted from work of Takanori Ikenaga. The experiments described herein comply with the “Principles of animal care”, publication No. 86-23, revised 1985 of the National Institute of Health, and were approved by the University of Colorado Health Sciences Center Institutional of Animal Care and Use Committee.
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Finger, T.E. Sorting food from stones: the vagal taste system in Goldfish, Carassius auratus . J Comp Physiol A 194, 135–143 (2008). https://doi.org/10.1007/s00359-007-0276-0
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DOI: https://doi.org/10.1007/s00359-007-0276-0