Cerebellar efferent neurons in teleost fish

Abstract

In tetrapods, cerebellar efferent systems are mainly mediated via the cerebellar nuclei. In teleosts, the cerebellum lacks cerebellar nuclei. Instead, the cerebellar efferent neurons, termed eurydendroid cells, are arrayed within and below the ganglionic layer. Tracer injections outside of the cerebellum, which retrogradely label eurydendroid cells demonstrate that most eurydendroid cells possess two or more primary dendrites which extend broadly into the molecular layer. Some eurydendroid cells mostly situated in caudal portions of the cerebellum have only one primary dendrite. The eurydendroid cells receive inputs from the Purkinje cells and parallel fibers, but apparently do not receive inputs from the climbing fibers. Eurydendroid cells of the corpus cerebelli and medial valvula project to many brain regions, from the diencephalon to the caudal medulla. A few eurydendroid cells in the valvula project directly to the telencephalon. About half of the eurydendroid cells are aspartate immunopositive. Anti-GABA and anti-zebrin II antibodies that are known as markers for the Purkinje cells in mammals also recognize the Purkinje cells in the teleost cerebellum, but do not recognize the eurydendroid cells. These results suggest that the eurydendroid cells receive GABAergic inputs from the Purkinje cells. This relationship between the eurydendroid and Purkinje cells is similar to that between the cerebellar nuclei and Purkinje cells in mammals. The eurydendroid cells of teleost have both dissimilar as well as similar features compared to neurons of the cerebellar nuclei in tetrapods.

Participation of Neurochemical Signaling in Adult Neurogenesis and Differentiation

“…Detection of nNOS in eurydendroid cells of masu salmon cerebellum confirms received our earlier data on histological labelling of NADPH-d in the neurons of this type of fish [46]. According to Ikenaga with co-authors [47], most of the eurydendroid cells in fish are aspartat-ergic and receive GABA-ergic impulses from the Purkinje cells. According to our data, the population of eurydendroid cells of masu salmon in cerebellum contains GABA-ergic and PA-ergic cells.…”

Development of the cerebellum and cerebellar neural circuits

“…In the granule cell layer, synaptic interactions occur among mossy fibers, granule cells, and Golgi interneurons in the cerebellar glomeruli. Eurydendroid cells are located in the vicinity of the Purkinje cell layer, contact Purkinje cell axons, and send their axons through the granule cell layer to different areas outside the cerebellum in teleost (Murakami and Morita, 1987;Folgueira et al, 2006;Ikenaga et al, 2006).…”

Neuromodulation of early electrosensory processing in gymnotiform weakly electric fish

“…These cerebellar eurydendroid cells are thought to perform functions similar to those of deep cerebellar nuclei neurons in tetrapods (Finger, 1978;Ikenaga et al, 2006). A recent in situ hybridization study (Toscano-Márquez et al, 2013) showed that M3 is the only muscarinic receptor present in the ELL and that its mRNA is homogenously distributed across pyramidal cells in all three tuberous ELL segments (Fig.2A) et al, 2013).…”