Final answer:
Damage to the thalamus can result in a variety of sensory deficits, while damage to the SI cortex specifically affects touch and proprioception. In a thoracic spinal cord hemisection, such as from an accident, expect motor function loss in one leg, with loss of fine touch ipsilaterally and preservation of pain sensation contralaterally. A stroke in the temporal lobe can lead to impairments in hearing, language, and memory.
Step-by-step explanation:
Symptoms of Lesion in Thalamus or SI Cortex
Lesions in the thalamus or the primary somatosensory cortex (SI Cortex) can result in notable neurological and sensory deficits. The thalamus acts as a relay station for most sensory information on its way to the cortex. Damage to the thalamus can thus lead to a wide range of symptoms, such as sensory loss, pain, paresthesia, and sometimes changes in consciousness. If the SI cortex is affected, deficits in fine touch, proprioception, and two-point discrimination can be observed. These areas of the brain are critical for the processing of sensory information and enabling conscious perception of stimuli.
In cases of a thoracic spinal cord hemisection (such as might occur following a motorcycle accident), one might expect a loss of motor function in one leg. On the side of the injury leading to paralysis (ipsilateral), a patient may experience loss of fine touch and proprioception due to damage in the dorsal column-medial lemniscus pathway, which carries these sensations and ascends on the same side as the source. Pain and temperature sensations, carried by the spinothalamic tract, would still be perceived because these fibers decussate immediately upon entering the spinal cord and ascend on the opposite side (contralateral) from their source.
Lastly, damage to the temporal lobe due to a stroke can result in deficits related to hearing, language comprehension, and memory formation. Each region of the cerebral cortex is associated with specialized functions, and the temporal lobe is no exception.