Q Is the tubular-dorsal nervous system of chordates associated to radial or lateral symmetry? How does that explain the complexity level of the nervous system reached by the vertebrate evolutionary branch?
The tubular and dorsal nervous system of chordates is related to the cephalization in these animals and to bilateral symmetry.
The presence of neural integrating centers with concentration of neurons in the brains and the spinal cord (CNS referred as central nervous system) allowed the increase of the interaction complexity between these environment and the animals. Receptor (afferent conduction) and efferent (motor, behavioral and regulatory reactions) functions come out more sophisticated in chordates due to the presence of more well-developed neural networks.