- As established, the M1 is responsible for different parts of the body 
- However, an important distinction to make is whether the M1 is responsible for muscle contraction or directional movement of different body parts
- The M1 is ultimately responsible for both 

Breakdown of M1: Muscle Contraction vs. Movement

- As show below, different regions of the body will take up dispropriate amounts of space in the M1
- Another way of visualizing this phenomena is through the "motor homunculus" which shows a figure's body parts enlarged to various degrees, based on the space it takes up in the motor cortex 
- However, this has been described as "oversimplifying"  the organization of the M1, which can be increasingly complex

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- Region of the brain involved in the initiation of movement 
- Specific regions of the motor cortex are associated with the movement of individual body parts/muscles ("maps" of M1 exhibit this concept)
- The M1 exhibits "learning" when movement is habituated

Primary Motor Cortex (M1)

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

Size Breakdown of M1

- As an organism continues to repeat the same movement over and over (such as grasping an object, or being able to point at an object) it will take less "effort" for the brain to initiate this movement
- This makes the organism more efficient in its ability to complete certain tasks
- This is evidence of an organism's ability to learn

Learning and the M1

Primary Motor Cortex Library 

- Recent studies have looked at the cell types that constitute the M1, and have utilized a cell population known as cortico-motoneuronal cells (CM) to differentiate between different regions of the M1 (described as "old" vs "new")

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