Which of the following manifestation occur secondary to ablation of the 'somatosensory area I' of the cerebral coex?
Widespread bilateral excision of somatosensory area I result in person being unable to localize discretely the different sensations in the different pas of the body. Somatosensory area 1 is located in the posterior bank of the central sulcus and on the crown of postcentral sulcus. This area corresponds to Brodmann's area 3a, 3b, 1 and 2. Neurons in area 1 and 3b are responsive to cutaneous inputs both rapidly and slowly adapting. Area 2 and 3a respond to deep stimuli, with area 3a responsive to muscle afferents and area 2 to joints. Area 3b is critical for the performance of tactile discrimination based on shape or texture of a stimulus. Inactivation of this area leads to lack of appreciation of the quality or existence of tactile stimuli. Lesion of area 1 disrupt performance based on texture but leaves intact performance based on stimulus size, whereas lesion in area 2 produces opposite effect. Ref: Guyton and Hall - Textbook of Medical Physiology, 10th Edition, Page 546; Ganong's Review of Medical Physiology, 22nd Edition, Pages 139-40; Fundamental Neuroscience, Volume 1 By Larry R. Squire, 2nd Edition, Page 689
Total loss of pain sensation
Total loss of touch sensation
Loss of tactile localization but not of two point discrimination
Loss of tactile localization and two point Discrimination