motor control for SCI

Requirements for bipedal locomotion

1. Ability for reciprocal LE movement

2. Postural control

3. Initiation

4. Adaptability

.problems with only focusing on compensations

• Lack of weight bearing

Lack of weight-bearing

• Immobility

• Osteoporosis, pulmonary, skin complications reconditioning, obesity

• When chair → scoliosis

Lesion models

• Spinal preparation

• Decerebate prepration

• Decorticate preparation

Spinal preparation

Below medulla

Decerebrate

Below red nucleus above medulla

Decorticate preparation

Above red nucleus

What does spinal cord have basic circuitry for?

• Alternate activation of flexors and extensors within a limb: thymine activity

• reciprocal limb movements

Hypotheses about alternating activity

1. Reflexes: sensory input is mandatory

2. Motor program where sensory input is not mandatory but modulatory

What can pattern generate without?

1. Supraspinal input

2. Somatosensory input

What does spinal card have

Central pattern generators

• intrinsic capability for alternating flexion-extension actions of extreme NES

CPG for reciprocal movement

• Generators on both sides

• When is active, the other is turned off

Major components of locomotor CPG

1. rhythm-generating network

2. Networks responsible for flexor-extensor alternation

3. Network securing left-right alternation

Additional info about locomotor GPG

• Have intrinsic excitability once stimulated but may had to be initiated first

• Modulated by sensory input

Prophospinal interneurons

• Communicate into over short and long distances within spinal cord

• Coordinate different parts of the body by linking motor circuits that control muscles across the body

Short networks

Connect adjacent lumbar segments

Long network

Connect cervical and lumbar enlargements

Hip flexor stretch

Ia fibers

• control the transition from stance to swing

What info do you get from hip extensors

Ib afferents from GTOs prolong stance duration and delay swing

• keep extensors active in terminal stance

Supraspinal inputs

• Corticospinal pathways

• other descending inputs

• propriospinal neurons and pathways

Supraspinal control

• Initiation of walking

• online adjustments to errors during walking

• visual guidance/ obstacle avoidance I visual cortex via motor cortex

Regulation of IN

• Sensing input helpful for timing and amplitude of stepping movements

• descending pathways are necessary for initiation and adaptive control of stepping movements

Basal ganglion’s function in locomotion

Action selection: selects locomotor activity dependent un the goal

MLR and reticulospinal neurons function in locomotion

intitate locomotion by activating spinal CPG

Spinal CPG and networks function in locomotion

Generate rhythm and pattern of locomotor behavior

Muscle and skin affronts function in locomotion

Modulate ongoing locomotor activity

Cerebella motor circuits function in locomotion

Adapt locomotor commands to external perturbations

• coordinate locomotion with other activities

Motor cortex, pre motor cortex function in locomotion

Active during skilled locomotor behaviors