The cortical homunculus is a visual representation of how the brain truly views the human body. More specifically, it depicts the differences in the brain’s dedication to individual areas of the body.
There are two types of cortical homunculi – the motor homunculus and the sensory homunculus. The motor homunculus model is based on the information exchange between the body and the part of the brain responsible for motor function – the primary motor cortex. As the name suggests, the motor homunculus is a proportionate representation of the brain’s dedication to the parts of the body responsible for motor functionality. In other words, the more brain power involved in the planning, execution and control of a body part’s movements, the larger the body part is on the clay figure, thus giving a simple, yet accurate visual representation of the brain’s dedication to different areas of motor function.
Similarly, the sensory homunculus model is a visual representation of the brain’s dedication to the sensing of information of each body part. Again, this directly translates; the larger the brain’s efforts in sending/receiving sensory information to each body part, the larger the body part is on the figure. The part of the brain that is responsible for this sensory exchange is the primary somatosensory cortex, and with the visual aid of the sensory homunculus, we can gain a better insight into the relationship between this cortex and the different areas of the human body in relation to sensing.
Both the motor and sensory areas of the brain value the hands above all else. The hands help to navigate our way through this world in what seems like an automatic function. Little do we ever stop to think that as we type, lift or even gesture, that our brain is concurrently dedicating so much to these functions, let alone the idea that it’s focusing more on the hands than anything else. On the other end of the scale, the brain is giving perhaps the least amount of dedication to areas such as the limbs. The limbs work only to move our hands and feet into place, so while they do require attention, they don’t necessarily need the same amount of dedication as the eyes, mouth or hands.
This concept was developed by Wilder Penfield in the 1930’s. Penfield performed surgeries on patients with epilepsy and often made use of his valuable time with the live brain by mapping the specific areas of the brain as related to parts of the body. This resulted in the first, more primal cortical homunculus, which shows (in the diagram below), which areas of the brain coincide with specific parts of the body.
While incredibly creepy, the cortical homunculi provide for a more mindful experience. As you read this, pay attention to your body – which areas are most utilised? It’s an awakening experience to acknowledge how powerful the human brain is, rather than to simply function automatically through every single process without ever giving it a deeper thought. The human brain is truly an astonishing masterpiece that we often take for granted; stay mindful.