Why the homunculus is wrong. You’ve probably heard of or seen the homunculus (Latin for “little human”) before.  If not, he’s a representation of how much brain is devoted to sensation for the parts of the body or how “sensitive” each area is to touch (basically boiling down to the number of receptors there).  There is also a motor homunculus that doesn’t look too much different about which parts of the body have large parts of the brain devoted to motor movement.  For instance, the hands which have a lot of fine touch receptors and dexterity are represented largely in the brain, as compared to the trunk, which has less proprioception (touch reception) and less movement. The homunculus is wrong because our brain is plastic.  The amount of touch devoted to each area can change over time and from person to person.  For instance, violinists, who have to be able to move fingers on their left hand with a lot of dexterity and feel the strings of the violin well will have a lot more brain power devoted to those fingers than to their palm or other areas of the body- or non-violin players.  Additionally, we know that people who have lost limbs have those areas of the brain redistributed so that those that used to pick up or send signals to the part of the body that was lost will now do something else (there have been cases of late amputations where the person can feel their thumb on their cheek and the like- the brain didn’t do as great a job rewiring as it should have).  The brain is constantly changing and making itself more efficient!  The homunculus is a clever idea, but it doesn’t represent accurately the differences over time and between individuals.  [Image Source]

Why the homunculus is wrong.

You’ve probably heard of or seen the homunculus (Latin for “little human”) before.  If not, he’s a representation of how much brain is devoted to sensation for the parts of the body or how “sensitive” each area is to touch (basically boiling down to the number of receptors there).  There is also a motor homunculus that doesn’t look too much different about which parts of the body have large parts of the brain devoted to motor movement.  For instance, the hands which have a lot of fine touch receptors and dexterity are represented largely in the brain, as compared to the trunk, which has less proprioception (touch reception) and less movement.

The homunculus is wrong because our brain is plastic.  The amount of touch devoted to each area can change over time and from person to person.  For instance, violinists, who have to be able to move fingers on their left hand with a lot of dexterity and feel the strings of the violin well will have a lot more brain power devoted to those fingers than to their palm or other areas of the body- or non-violin players.  Additionally, we know that people who have lost limbs have those areas of the brain redistributed so that those that used to pick up or send signals to the part of the body that was lost will now do something else (there have been cases of late amputations where the person can feel their thumb on their cheek and the like- the brain didn’t do as great a job rewiring as it should have).  The brain is constantly changing and making itself more efficient!  The homunculus is a clever idea, but it doesn’t represent accurately the differences over time and between individuals. 

[Image Source]