Cortical homunculus

Basic Definition
Specifically: A physical representation of the primary sensorimotor cortex, i.e., the portion of the human brain directly responsible for the movement and exchange of sense and motor information (namely touch: sensitivity, cold, heat, pain etc.) of the rest of the body.

The resulting image is a grotesquely disfigured human with diproportionately huge hands, lips, and face in comparison to the rest of the body. Because of the fine motor skills and sense nerves found in these particular parts of the body they are represented as being larger on the homunculus. A part of the body with fewer sensory and/or motor connections to the brain is represented to appear smaller.

The Cortical Homunculus is a visual representation of the concept of "the body within the brain" that one's hand or face exists as much as a series of nerve structures or a "neuron concept" as it does a physical form. This concept relates to many neuro-biological phenomena including "phantom limb".

Images (external and probably copyrighted)

 * Sensorimotor Cortex, a diagram of the body mapped onto the brain
 * Sensory homunculus, a 3D model of the male human body with size proportional to sensory cortial area

See Also: Homunculus