- 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

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")

Subdivisions of M1

- 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

Smith College

- Our motor cortices help to facilitate the movements of our body in different ways
- There are two motor cortices: 
- Primary Motor Cortex (referred to as M1) 
- Nonprimary motor cortex (which contains the premotor cortex and the supplementary motor area), is anterior to M1 

Motor Cortices

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

Behavioral Neuroscience 8th Edition

Primary Motor Cortex (M1)

- Contributes to movement by "communicating" (sending messages) to brain stem and spinal cord, and by regulating M1
- Contains the supplementary motor area (SMA) and the premotor cortex

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