THINKER'S ALMANAC - January 26

If we draw a picture of the human body based on how the human brain sees it, why is it a distorted figure that looks very little like a typical human?

 

Subject:  Cortical homunculus - The brain’s map of the body  

Event:  Birthday of neuroscientist Wilder Graves Penfield, 1891  

 

Imagine what your body would look like if each of its parts were in proportion to how much of your brain was dedicated to sensing with them or to how much of your brain was dedicated to moving with them. How much larger, for example, would your nose be in comparison to your foot?

Because of the work of the neuroscientist Wilder Penfield -- who was born on this day in Spokane, Washington, in 1891 -- we have an accurate picture of how the human brain sees its body.  

Penfield’s cartoon depiction of the human brain is called the cortical homunculus, or “cortex man.”  This cartoon presents a distorted image of the human body based on how much of the brain is dedicated to the motor or sensory functions of different body parts.  Because, for example, a large portion of the brain is dedicated to sensing with and controlling the movement of the fingers and the lips -- as opposed to say the arms or the legs -- these features are drawn to appear much larger than they appear on an actual human (1).

Recall, Retrieve, Recite, Ruminate, Reflect, Reason:  What is the cortical homunculus?

Challenge - My Eyes have Seen the Glory of the Homunculus:  After a meal, you might have heard someone use the expression, “My eyes were bigger than my stomach.”  In this context, it is obviously meant in a figurative rather than literal sense.  However, with knowledge of the cortical homunculus, you might argue that the expression is literally true.  Explain.

Sources:

1-PBS. “Wilder Penfield 1891 - 1976.”