Final answer:
The route of the Dorsal Root Ganglion Pathway begins with neurons at the dorsal root that enter the spinal cord and ascend within the dorsal column system, decussating and synapsing at the thalamus, and eventually reaching the cerebral cortex.
Step-by-step explanation:
The pathway of the dorsal root ganglion to the brain starts when a sensory neuron’s axon enters the dorsal root and then joins the dorsal column white matter in the spinal cord. These axons are arranged in the dorsal column such that those from the lower body are medially placed, and the axons from the higher body levels are placed laterally. This system consists of two major tracts: the fasciculus gracilis, carrying sensory inputs from the lower body, and the fasciculus cuneatus, carrying inputs from the upper body and arms.
This dorsal column system involves three successive neuron types. The first neuron is located at the dorsal root ganglion, the second neuron is found within the spinal cord and their axons decussate, meaning they cross to the opposite side before ascending. They project to the thalamus in the brain. Here, they synapse with the third neuron type in their pathway which then projects to the cerebral cortex, ending specifically in the postcentral gyrus.