The observation of distinct locomotor behaviour presented by the different zebrafish embryos is consistent with the findings of previous studies. From 17 hpf, zebrafish embryos demonstrate spontaneous tail coiling by contracting the sides of its tail, a form of specialised locomotor behaviour activity (Brustein et al., 2003). Spontaneous tail coiling is not myogenic but arises from the innervation of functional motorneurons, which are situated in the spinal cord, and the frequency of the activity is most enhanced in 19 hpf embryos (Saint-Amant and Drapeau, 1998). Supraspinal input is not depended upon and neurotransmitters such as glutamate and glycine do not regulate this form of locomotor behaviour (Saint-Amant and Drapeau, 2001 cited in Downes and Granato, 2005).
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This is due to the development of a set of specific neurons in each segment of the spinal cord (Brustein et al., 2003). In spontaneous tail coiling, each segment of the spinal cord is innervated by three primary motorneurons and they are known by their longitudinal position (Westerfield et al., 1986). The innervation of locomotor behaviour is also regulated by interneurons (Brustein et al., 2003). The axon of the interneurons will either ascend or descend along the spinal cord and as development progresses different types of interneurons such as commissural longitudinal ascending and ventral medial interneurons will arise (Hale et al., 2011). The depolarisation of these neurons occur periodically, which gives rise to the spontaneous tail coiling behaviour (Saint-Amant and Drapeau, 2000). The slow depolarisation arises early on in development from between 17 and 20 hours post fertilisation to produce action potentials for the initiation of activity (Brustein et al.,
This is due to the development of a set of specific neurons in each segment of the spinal cord (Brustein et al., 2003). In spontaneous tail coiling, each segment of the spinal cord is innervated by three primary motorneurons and they are known by their longitudinal position (Westerfield et al., 1986). The innervation of locomotor behaviour is also regulated by interneurons (Brustein et al., 2003). The axon of the interneurons will either ascend or descend along the spinal cord and as development progresses different types of interneurons such as commissural longitudinal ascending and ventral medial interneurons will arise (Hale et al., 2011). The depolarisation of these neurons occur periodically, which gives rise to the spontaneous tail coiling behaviour (Saint-Amant and Drapeau, 2000). The slow depolarisation arises early on in development from between 17 and 20 hours post fertilisation to produce action potentials for the initiation of activity (Brustein et al.,