What Is the Somatosensory Cortex?
The somatosensory cortex is an area of the brain which processes input from the various systems in the body which are sensitive to touch. People often think of touch as a single sense, but in fact several different sensory experiences are involved in touch, including specific sensitivity to pain, sensitivity to temperature, and the body's proprioception system which monitors the body's place in space. The somatosensory system as a whole is extremely refined and highly sensitive, allowing people to detect and interpret a wide variety of sensations.
Across the body, a network of nerve cells react when they experience sensations related to physical perception. Specialized cells react specifically to pain, while others fire in response to passing breezes, pressure, and a wide variety of other sensations such as the heat of the sun or the chill which emanates from an open refrigerator. Impulses travel along these nerves through the somatosensory system to reach the thalamus of the brain, which passes the information on to the somatosensory cortex.
The somatosensory cortex is located within the postcentral gyrus, a structure around the middle of the cerebral cortex. Different areas of the somatosensory cortex correspond to input from different groups of nerve cells; the largest areas correspond to areas such as the face, which are highly sensitive. Researchers have identified the precise regions where sensations are interpreted, and have come up with representative human figures which show proportionally how much of the brain is dedicated to sensation from various areas of the body.
The technical term for such a a figure is a homunculus, or “little man.” People may refer to a sensory homunculus in particular to make it clear that they are referring to a visual representation of the somatosensory cortex. The head of the figure is distorted because so much of the somatosensory cortex is dedicated to sensations from the head, while the limbs are relatively small, as they have fewer sensory cells.
When part of the somatosensory system becomes impaired, people can experience loss of sensation. Impairments can happen at any level along the way, from damage to the sensory neurons in the skin to an injury to the brain which interferes with the function of the somatosensory cortex. When neurological problems which interfere with sensation are identified, a neurologist can conduct tests to determine the source of the problem so that treatment recommendations can be made to the patient.
Written by S.E. Smith
