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Reticulospinal and Vestibulospinal Neurons in the Young Larva of a Teleost Fish, Brachydanio rerio

1982; Elsevier BV; Linguagem: Inglês

10.1016/s0079-6123(08)64122-9

1875-7855

Charles B. Kimmel,

Physiological and biochemical adaptations

This chapter discusses reticulospinal and vestibulospinal neurons in the young larva of a teleost fish, Brachydanio rerio. The neurons are located in the reticular formation and vestibular nuclei and appear to represent the entire projection from the brain to the deeper levels of the cord. The number of cells in this population is small, their arrangement in the brain is stereotyped, and some of them can be individually recognized in the sense of identified neurons characteristic of many invertebrate species. The M-neuron in the brain receives synaptic input from the periphery and perhaps from long ascending and descending central axons. The M-cell projects to interneurons and spinal motoneurons. Comparisons between the other zebrafish reticulospinal cells and those in the distantly related lamprey reveal many morphological similarities. This suggests that the system as a whole is conservative and phylogenetically ancient. The functional roles of the other neurons that project to the cord have not been studied. Occasionally, in normal fish and more frequently in fish where the M-cells have been experimentally deleted, large startle responses are observed that are not initiated by the M-cell.