Lecture 15- Control of Movement Flashcards
What are the four basic neural systems invovled in controlling movement?
- Local spinal cord and brainstem circuits
- Descending systems
- Cerebellum
- Basal nuclei
Where do motor neurons have their cell body?
Ventral horn of spinal cord
What do motor neurons form?
The final common pathway between the brain and muscle
Where do acetylcholine receptors sit in terms of the nerve terminal and what does this mean in terms of their pattern?
- Sit directly beneath nerve terminal
- Means that receptor locations correspond closely with nerve terminal branches
Describe the circuit formed with local motor neurons?
- Lower motor neurons in brainstem and spinal cord send axons out of CNS to make direct excitatory contact with skeletal muscle fibres to cause movement
- Sensory and local neurons provide input to lower motor neurons (feedback)
What are central pattern generators?
-Networks of neurons in spinal cord capable of driving rhythmic,
stereotyped behaviours (eg walking, breathing) without input from higher centers
- This activity may be initiated & modulated by input from higher centers (if required: override mechanism)
-Alternating rhythmic activity typically arises out of bursting activity of
neurons, and reciprocal inhibition (coupled to action of other muscles that need to be inhibited e.g. flexion in one and extension in other)
True a false a large amount of the brain is invovled in the planning + performing of movements…
True!
This means damage to many different parts of the brain can result in a decrease in motor function
What parts of the brain are invovled in planning movement (the sequence)?
- Decision made in frontal lobes
- The premotor cortex coordinates with the basal nuclei and cerebellum (providing sensory info) to send signal to primary motor cortex
- Primary motor cortex then feeds onto lower motor neurons to cause action/ activity
What are the two ways in which the basal nuclei can adjust patterns of movement?
- Alter the sensitivity of pyramidal cells to adjust the output along the corticospinal tract
- They change the excitatory or inhibitory output of medial and lateral pathways
How does the cerebellum work to alter motor activity?
-Monitors balance and equilibrium and adjust upper motor neurons activity
-Helps plan, execute and learn motor programs
-Integrates sensory info with planned events
-Organises timing of muscle contractions
-Compares planned movement with actual result, modifies ongoing
activity to make movements smooth and accurate
What areas of the cortex are primarily invovled in producing movement?
- Pre-central gyrus= primary motor cortex
- SMA= supplementary motor area
What do we mean when we say somatotopic organization of primary motor cortex?
- There is a ‘map’ in the cortex with each area connecting to a specific body part
- Area devoted to muscles in each region related to level of fine control & movement complexity (i.e not to muscle size)
Because of somatotopic organization what is the result of damage to a particular muscle area?
- Damage to the corresponding cortex region
- Remember outputs are crossed so damage to cortex on the left side will cause damage to body areas in the right side of body
How is somatotopic organization plastic?
-Area may change as a function of its use e.g. if your a pianist area associated with fine movement in fingers may expand
List the two descending pathways…
- Corticospinal tract
- Brain stem pathways
