Ion Channel Proteins
Primary Somatosensory Cortex
The primary somatosensory cortex (SI) of the brain 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 organized (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).