At what levels of the nervous system are all types of somatic sensory information represented on the contralateral side: the spinal cord, the medulla, the pons, the midbrain, the thalamus, the cortex?
Information from the dorsal columns crosses at the level of the medulla after synapsing in the dorsal column nuclei, so dorsal column information is contralateral as it courses through the medial lemniscus to synapse in the thalamus and then in the cortex. The trigeminal touch pathway crosses at the level of the pons to synapse contralaterally in the VP nucleus of the thalamus. Information in the spinothalamic tract crosses early, at the level of the spinal cord, so all its information is contralateral by the time the afferents reach their targets in the thalamus. As a result, all types of somatic sensory information are represented on the contralateral side at the level of the thalamus