Functional hierarchy of the motor system (and motor control) Flashcards
What are the 3 stages in motor control?
Strategy
Tactics
Execution
Describe “strategy”.
The way by which a movement is designed to reach a specific goal
Which parts of the brain are involved in strategy of motor control?
Neo-associative cortex
Basal ganglion
Describe “tactics”.
The sequence of spatio-temporal muscle contractions to achieve a goal smoothly and accurately
Which parts of the brain are involved in tactics?
Motor cortex
Cerebellum
Describe “execution”.
Activation of motor neuron and interneuron pools to generate a goal-directed movement
What do the lateral pathways of the spinal cord do?
Controls voluntary and distal movements
What are the tracts of the lateral pathway?
Rubrospinal
Corticospinal
What do the ventromedial pathways of the spinal cord do?
Control posture and locomotion
What part if the brain controls the ventromedial pathways?
Brainstem
What part of the brain controls the lateral pathways?
Under direct cortical control
What are the tracts of the ventromedial pathways?
Tectospinal
Vestibulospinal
Pontine reticulospinal
Medullary reticulospinal
What effects would a lesion of just the corticospinal tract have?
Loss of fine movements in arms and hands
Can no longer move shoulders, elbows, wrists or fingers independently
Function restored after a few months as rubrospinal tract takes over
What effects would lesion affecting both the corticospinal and rubrospinal tracts have?
Loss of fine movements in arms and hands
Can no longer move shoulders, elbows, wrists or fingers independently
Where do the ventromedial pathways innervate?
Trunk and antigravity muscles in limbs
Where are decisions on motor control taken?
Prefrontal and parietal cortex?
Describe how we “plan and prepare” for movement.
Decision making neurons in the pre-motor area fire 1 second before movement occurs
They fire when a movement is imagined
“Mirror neurons” fire when others perform an action
This allows us to understand and rehearse a movement
How do we stabilise movement?
Change in body position initiates rapid compensatory feedback messages from brainstem vestibular nuclei to motor neurones which then corrects postural instability
Brainstem reticular formation nuclei also initiate feedforward anticipatory adjustments
What is the corpus striatum?
A nucleus in the subcortical basal ganglia of the forebrain
What are the 2 principal nuclei of the corpus striatum?
Caudate and putamen
What does the caudate nucleus do?
Receives input before limb/trunk movement
Plays vital role in storing and processing memories
What causes Parkinson’s disease?
Degeneration of neurones in substantia nigra
What is the effect of Parkinson’s disease?
Hyperkinesia
What causes Huntington’s disease?
Profound loss of caudate, putamen and globus pallidus
How may Huntington’s disease present?
Mood swings Clumsy/jerky movement Problems swallowing Difficulty concentrating Memory lapses
