Sensory Pathways 1 Sensations are carried by various sensory pathways to the brain. These pathways consist of a series of three neurons. First-order neurons are located in the periphery. They synapse with a second-order neuron in the spinal cord or brain. These, in tum, synapse with a third-order neuron in the thalamus. Third order neurons carry information to the primary sensory cortex. .