Final answer:
The 3rd-order neuron of the spinothalamic tract does indeed travel to the primary somatosensory cortex, specifically to the postcentral gyrus, making the statement true.
Step-by-step explanation:
The statement that the 3rd-order neuron of the spinothalamic tract travels to the primary somatosensory cortex (postcentral gyrus) is True.
The spinothalamic tract is responsible for transmitting pain and temperature sensations. This sensory pathway involves three neurons: the first neuron resides in the dorsal root ganglion, the second neuron is in the spinal cord, and after decussation, its axon ascends to the thalamus where it synapses with the third neuron.
The third neuron then projects from the thalamus to the primary somatosensory cortex, located in the postcentral gyrus, where the conscious perception of the stimulus occurs.