Answer
The fibers of the lateral spinothalamic tract decussate, but they eventually reach the somatosensory cortex by way of the thalamus.. These fibers carry impulses related to pain and temperature(heat/cold) from one side of the body to the contralateral somatosensory cortex for interpretration.
If a noxious stimulus is applied to the left leg of a subject, but in this subject the right lateral spino-thalamic tract has been severed anterior to the point of decussation, the pain stimulus would fail to reach the somatosensory cortex.
Consequence. The victim would experience no pain.
Work Step by Step
The lateral spinothalamic carries pain and temperature stimuli to the somatosensory cortex for interperpration. Because the fibers in this tract decussate,, beyond the pont of decussation stimuli from the left leg , for example, are taken to the cortex by the right component of this lateral spinothalamic tract. Therefore, if in a subject, the right component of the spinothalamic tract above the point of decussation is severed , a wound inflicted on this subject's left leg would not be experienced as painful.
