This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Ablation of the 'somatosensory area I' of the cerebral coex leads to : 
Select and explain. 
A. Total loss of pain sensation, B. Total loss of touch sensation, C. Loss of tactile localization but not of two point discrimination, D. Loss of tactile localization and two point discrimination
D: Loss of tactile localization and two point discrimination
Answer: D: Loss of tactile localization and two point discrimination 
Explanation: D i.e. Loss of tactile localization & two point discrimination Functions & Lesions Somatosensory area I (SI) Primary somatosensory area (SI) is Brodmann's area 1, 2, 3 situated in postcentral gyrus. Ablation of SI would lead to coical pattern of sensory loss. Lesion in this area produce contralateral impairment of: - TouchQ - Sterognosis - Pressure - Barognosis - Proprioception - Cutaneographia - Two point discrimationQ Spinal cord lesion Brainstem lesion Thalamic lesion Coical lesion Five patterns are seen depending Loss of pain & temperature Hemisensory loss of Patients is able to recognize all upon whether there is: on ipsitateral face and all modalitiesQ sensation but localizes them - Complete transaction opposite side of bodyQ. poorly - Hemisection (Lateral medullary - Loss of two point - Central cord section syndrome)Q discriminationQ - Posterior column section sensation) - Sensory inattention