Descending pathways to the spinal cord in teleosts in comparison with mammals, with special attention to rubrospinal pathways

Abstract

In this article we review descending neural pathways to the spinal cord in teleosts, compared with mammals. Descending pathways to the spinal cord are crucial in controlling various behaviors in vertebrates. The major difference between teleosts and mammals is the lack of corticospinal (or palliospinal) tracts. Other descending pathways, which originate from the brain stem, are basically identical in teleosts and mammals. This suggests the presence of common systems in the spinal motor control by higher order centers. The homologue of nucleus ruber remained unclear in teleosts until recently, and this review pays special attention to the rubrospinal tract.

Primitive Reflexes in Very Low Birth Weight Infants Later Diagnosed with Autism Spectrum Disorder

“…Why did infants with than without ASD show more abnormalities in primitive reflexes? Primitive reflexes are considered to be mediated by the brainstem, and gait and movement develop thorough bidirectional connections among the cerebrum, cerebellum and midbrain [21,22].…”

Corticospinal vs Rubrospinal Revisited: An Evolutionary Perspective for Sensorimotor Integration

“…Thus, it seems that the presence of RN is a first trial of evolution for the control of appendages for locomotion in water, at least in rays and lungfishes. On the other hand, in other vertebrates with undulating movements, such as lampreys (Pombal and Megías, 2011) and sharks (Smeets and Timerick, 1981), the RN has not been found, nor has its function in teleosts (Yamamoto et al, 2017). Likewise, this nucleus has not been found in some limbless tetrapods, such as caecilian (Ichthyophis kohtaoensis) (Naujoks-Manteuffel et al, 1988) and snakes (Python reticulatus) (Ten Donkelaar, 1976).…”

“…Thus, the RN sends axons to the ventrolateral region of the spinal cord (Figure 1). However, its role in fine motor control remains to be studied (Yamamoto et al, 2017). The drawings show a dorsal view of the brain of representative species of each group, as well as a transverse section of the spinal cord.…”

Transgenic tools targeting striatal and pallidal subpopulations revealed evolutionary conservation and specialization of the cortico-basal ganglia circuit in zebrafish

“…Lastly, we searched for a motor output pathway from the pallium. Although teleosts are thought to lack a direct projection from the pallium to the spinal cord (Yamamoto et al, 2017), it is still possible that there are functional counterparts of the mammalian corticospinal tract, which mediate motor commands from the pallium to the downstream motor circuits. In teleosts, the optic tectum, which is homologous to the mammalian superior colliculus, is known to control body movements (Helmbrecht et al, 2018; Isa et al, 2021).…”