Efference Copy and Sensory Reafference

Cerebellum and Information Processing

• The cerebellum receives a massive amount of sensory information (40 times more than it sends out).
• There are two main types of input:
  • Efference copy: A copy of the motor command sent from the cerebral cortex to the muscles. This tells the cerebellum what movement was intended.
    • The cerebellum receives efference copy from both the cerebral cortex and the motor neurons themselves.
  • Sensory reafference: Sensory information received from the body after a movement is made. This tells the cerebellum what movement actually happened.

Cerebellar Learning

• The cerebellum compares efference copy with sensory reafference.
• If the intended movement (efference copy) and the actual movement (sensory reafference) don’t match, the cerebellum makes adjustments.
• This is a form of associative learning, where the cerebellum learns to associate specific sensory feedback with specific parts of a movement.

Example: Serving a Tennis Ball

• As you serve a tennis ball, the cerebellum anticipates the sensory feedback you should feel at each stage of the movement.
• If you botch a serve, it’s because the sensory feedback you receive deviates from what the cerebellum expected.
• This feedback helps the cerebellum refine your movements for future attempts.

Overall

• The cerebellum plays a crucial role in motor control by using sensory information to ensure smooth and coordinated movements.
• The lecture will explore specific examples of cerebellar learning in the next segments.