Brainstem · Structure
Midbrain
Reflex eyes, ears, and the dopamine source.
The midbrain handles fast orienting reflexes — snapping your eyes toward a movement — and contains the substantia nigra, the brain's main supply of dopamine for movement.
What it does
- Reflexive eye and head orienting
- Auditory startle responses
- Producing dopamine for motor control
In the real world
Parkinson's disease
Parkinson's begins with the loss of substantia nigra dopamine neurons. Levodopa therapy and stem-cell transplants both target this tiny patch of midbrain.