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.
There are 31 pair of spinal nerves & each has a dorsal root and a ventral root. The dorsal root is sensory (all neurons conduct impulses into the spinal cord) while the ventral root is motor (all neurons conduct impulses out of the spinal cord). The dorsal root has a ganglion that contains the cell bodies of the sensory neurons that pass through the dorsal root.