Final answer:
The ascending tract carries somatosensory information from peripheral receptors to the cerebral cortex through various pathways such as the spinal cord and trigeminal system, using the dorsal column-medial lemniscus system and the spinothalamic tract. These involve three successive neurons and all sensory systems except olfactory pass through the thalamus on the way to the cortex. The correct answer is option B.
Step-by-step explanation:
The ascending tract refers to the somatosensory pathways through which sensory information is relayed from the peripheral nerves to the cerebral cortex. Specifically, tactile and various other sensations are detected by receptors located in the skin, muscles, tendons, and joints and transmitted to the brain. Below the neck, these stimuli follow pathways up the spinal cord, whereas stimuli from the head and neck utilize the trigeminal system.
In the case of signals from the upper limb and other body regions below the head, somatosensory information is commonly conveyed via two main pathways: the dorsal column-medial lemniscus system and the spinothalamic tract, each made up of three successive neurons.
For the head and face, the trigeminal pathway, which also consists of three successive neurons, carries information to the brain via different nuclei in brainstem regions such as the pons, medulla, and midbrain.
All these sensory inputs, except for olfactory signals, synapse in the thalamus before reaching the cerebral cortex – the site of conscious perception of sensory information.