PARKINSONS DISEASE & THE MOTOR SYSTEM
The Spinal Cord
- It takes imputs from the brain stem, cerebellum, and basal ganglia.
- It also sends information back to thalamus and cerebellum.
- Mediates complex reflexes.
- It contains its own motor programmes.
- Locomotion it is acyclic process. Walking, swimming, and flying use a repeating cycle. Switch
between gaits.
- Spinal cord has central pattern generator (CPG).
- Uses sensory feedback (locomotion).
- Spinal cord connects to the musculature via motor neurone. They exit from the ventral horn.
o Alpha motor neurones (large) – to muscle fibres.
o Gamma motor neurones (small) - to spindles,
o Beta motor neurons- to fibres and spindles.
Muscle Contraction
Release of Ach.
Activation of nAChRs.
Action potential in muscle fibre.
Co-contraction coupling via Ca2+ entry.
Sliding filaments cause contraction.
There are 3 different types of muscle fibres. They have different degrees of
summation and recruited in order.
Slow muscle fibres- weaker response.
Fast but slowly relaxing fibres
Fast and fast relaxing muscle fibres.
When you slowly increase the force of contraction of a muscle, slow muscle fibres will become active
first.
Spindles and Tendons
o These organs provide feedback.
o Muscle spindles detect stretch.
o Gamma fibres adjust length sensitivity.
o Golgi tendon organ (GTO) detects tension.
o Proprioception feedback.
o Muscle spindles and Golgi tendon organs are a form of sensation called proprioception. The muscle
spindles detect stretch whereas the GTO detect tension. The role of the gamma motor neurones is to
adjust the sensitivity of the muscle spindles by taking up the slack caused by contraction of the power-
generating muscle fibres which is caused by activity in the alpha motor neurones.
Spinal Cord Contribution to Locomotion
Stetch in phase increases output.
Stretch out of phase decreases output.
Spinal interneurons identified by transcriptomics. You can identify clearly
subtypes of interneurons.
Brust generators initiate movement.
Reciprocal connections.
Local reflexes modulate CPGs.
The Spinal Cord
- It takes imputs from the brain stem, cerebellum, and basal ganglia.
- It also sends information back to thalamus and cerebellum.
- Mediates complex reflexes.
- It contains its own motor programmes.
- Locomotion it is acyclic process. Walking, swimming, and flying use a repeating cycle. Switch
between gaits.
- Spinal cord has central pattern generator (CPG).
- Uses sensory feedback (locomotion).
- Spinal cord connects to the musculature via motor neurone. They exit from the ventral horn.
o Alpha motor neurones (large) – to muscle fibres.
o Gamma motor neurones (small) - to spindles,
o Beta motor neurons- to fibres and spindles.
Muscle Contraction
Release of Ach.
Activation of nAChRs.
Action potential in muscle fibre.
Co-contraction coupling via Ca2+ entry.
Sliding filaments cause contraction.
There are 3 different types of muscle fibres. They have different degrees of
summation and recruited in order.
Slow muscle fibres- weaker response.
Fast but slowly relaxing fibres
Fast and fast relaxing muscle fibres.
When you slowly increase the force of contraction of a muscle, slow muscle fibres will become active
first.
Spindles and Tendons
o These organs provide feedback.
o Muscle spindles detect stretch.
o Gamma fibres adjust length sensitivity.
o Golgi tendon organ (GTO) detects tension.
o Proprioception feedback.
o Muscle spindles and Golgi tendon organs are a form of sensation called proprioception. The muscle
spindles detect stretch whereas the GTO detect tension. The role of the gamma motor neurones is to
adjust the sensitivity of the muscle spindles by taking up the slack caused by contraction of the power-
generating muscle fibres which is caused by activity in the alpha motor neurones.
Spinal Cord Contribution to Locomotion
Stetch in phase increases output.
Stretch out of phase decreases output.
Spinal interneurons identified by transcriptomics. You can identify clearly
subtypes of interneurons.
Brust generators initiate movement.
Reciprocal connections.
Local reflexes modulate CPGs.
