Sex is a primary reward and it is the basis of pair-bond formation in voles. The striatum is part of the neuronal circuitry underlying a remarkable pair-bond formation in which both partners remain monogamous. It is important to note that the role of the striatum extends beyond that of movement and reward.
in human nervous system: The spinal cord. Associated with local regions of the spinal cord and imposing on it an external segmentation are 31 pairs of spinal nerves, each of which receives and furnishes one dorsal and one ventral root.
Depending on definition in humans there are twelve or thirteen cranial nerves pairs, which are assigned Roman numerals IâXII, sometimes also including cranial nerve zero. The numbering of the spinal nerves is based on the order in which they emerge from the brain, front to back (brainstem).nd, as noted, earlier there is reason to consider both the olfactory (I) and Optic (II) nerves to be brain tracts, rather than cranial nerves. Further, the very small terminal nerve (nerve N or O) exists in humans but may not be functional.