دانلود رایگان مقاله سانترال Griseum، یک همولوگ پریاکوئداکتال خاکستری در مارماهی

Abstract

Fear, a response to threatening stimuli and important for survival, is a behavior found throughout the animal kingdom. One critical structure involved in the expression of fear-related behavior is the periaqueductal gray (PAG) in mammals, and in the zebrafish, the griseum centrale. Here, we show in the lamprey, belonging to the oldest now living group of vertebrates, that a bilateral periventricular nucleus in the ventral mesencephalon has a similar location to that of the PAG and griseum centrale. It targets the pretectum and the substantia nigra pars compacta (SNc), expresses the dopamine D1 and D2 receptors and receives input from the pallium (cortex in mammals), hypothalamus, the raphe area and SNc. These are all hallmarks of the mammalian PAG. In addition, like in the zebrafish, there is an input from the interpeduncular nucleus. Our results thus suggest that a structure homologous to the PAG/griseum centrale was present very early in vertebrate evolution.

6. Conclusion

Fear-related behavior is common to all animals including humans and is vital for survival. This suggests that there is a common basic circuitry for fear-related responses. One structure that plays a pivotal role in this behavior is the mammalian PAG and the zebrafish GC. Here, we identify a structure in the lamprey that with respect to location, connectivity (Fig. 4) and expression of dopamine receptors is homologous to the PAG/GC. We thus show that also the lamprey GC is conserved as are other forebrain structures including the habenulae, basal ganglia and the pallial projection pattern (Stephenson-Jones et al., 2011, 2012; Ocana et al., 2015; Grillner and Robertson, 2016).