Ion Channel Proteins
Primary Somatosensory Cortex
- The primary somatosensory cortex (SI) is located just posterior to the central sulcus in the postcentral gyrus of the parietal lobe (Broadmann areas 3, 1, and 2).
- Using tactile stimuli from the skin, the somatosensory cortex produces sensations of touch, pressure, pain, temperature, and proprioception (or the somesthetic sensations), which it then localizes to specific body regions.
- This area also assesses the size, shape, and texture of objects based on their feel and helps judge body position (proprioception) using sensory input from the joints, muscles, and skin.
- Similar to the motor cortex, the primary somatosensory cortex is somatotopically organizated (or functionally organized by body region).
- The medial and superior portions of the cortex image sensations from the genitals, feet, legs, hips, trunk, head and arm regions.
- The lateral portions of the cortex image sensations from the hands, face, teeth, tongue, pharynx and intraabdominal regions.
- Each somatosensory cortex receives sensory input from the opposite side of the body.
- Neurons that carry information about touch cross over in medulla oblongata portion of the brain stem.
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- Neurons that carry information about temperature and pain cross over in the spinal cord, near their point of entry.
- If this area is damaged, an individual may ignore certain body regions (or neglect syndrome) or not be able to recognize objects from their feel (or agnosia).