Control of movement Flashcards
What are cognitive inputs?
These are there to understand what we want to do (relation to emotional and psychological).
What is proprioception?
This is sensory info that tells us where our limbs are in space.
What is the point of sensory (proprioceptive) feedback?
Make sure the movements we are making are appropriate.
Which propriceptors send info through the spinocerebellar pathway?
Muscle spindles (muscle length) and Golgi tendon organs (tension in muscles).
These dont reach the cortex (unconscious).
Which proprioceptors send info though the dorsal column pathway?
Pacinian corpuscle (pressure and vibration), Ruffini endings (tension stretch), kinaesthetic receptors (limb position and change).
These reach the cortex.
Does the spinocerebellar pathway decussate?
No.
What is proprioceptive deafferentation?
Loss of proprioception, can’t travel/ gain the afferent sensory info to the CNS (have to use sight to use limbs).
What is the purpose of the somatosensory cortex?
Early cognition.
Purpose of primary motor cortex?
Initiation of motor control.
Purpose of pre- motor cortex?
Developed patterns of movement.
Purpose of basal ganglia?
Scaling and action selection.
Purpose of cerebellum?
Refinement of motor control.
Purpose of brain stem nuclei?
refinement of motor control.
Purpose of spinal cord?
Spinal reflex loops (require proprioceptive info).
Where is the vestibular system?
Part of the inner ear.
How can the vestibular system sense the acceleration of movement?
Embedded in the bone of head so going to move when the head moves (can measure movements of the head).
Ball bearing and box model?
When the box is shaken with the ball bearing inside, the ball bearing moves a different way to the box as it has inertia so tries to stay still.
What are the features of the vestibule system?
-Vestibular nerve
-Scarpas ganglion
-Semi- circular canals
-Otolith organs (utricle and saccule).
What is scarpas ganglion?
Series of nerve cell bodies receiving from canals and otolith and passing to the nerve and brain.
How do otolith organs function as accelerometers?
The hair cells are embedded in support cells. These hair cells have stereo cilia that are embedded in a gel that have otoliths. These otoliths have inertia and so when movement occurs, they move the opposite way.
Which way do stereo cilia move to be negatively charged?
Stereocilia move away from the kinocilium (hyper polarise).
Which way do stereo cilia move to be positively charged?
Stereocilia move towards the kinocilium (depolarise).
What is the purpose of ampullae?
The cilia is inside the endolymph (fluid), when shaken, cilia moves and deflects the hair cells.
What are the 4 main targets of the vestibular nuclei?
-Eye muscles (where they move in comparison to head)
-Cerebellum (perfect/ smooth movements- embed info about how body needs to react).
-extensor LMNs (balance and posture)
-Cervical spinal cord (adjustment of head and awareness of how to control muscles of the neck).
What are problems due to vestibular apparatus damage?
-Dizziness (Deterioration of input)
-balance disorders
-lack of coordination (no input to cerebellum
-bouncing vision (no input to oculomotor nuclei).
What is the dorsal visual stream?
stream of info from occipital lobe to sensory associative areas.
What is the ventral visual stream?
Stream of info from the insula and temporal lobe memory areas (not as important effect on motor control- do I recall or remember this?)
What happens if you have loss of visual sense?
-loss of a major proprioceptive sense
-reliance on other proprioceptive modalities
-much more severe difficulties if other senses impaired.
Role of basal ganglia and cerebellum in the control of movement model?
These monitor what’s happening and adjust motor programmes (no control of interneurons- just interact in 2 way feedback to monitor).
What is the purpose of the basal ganglia?
-Scaling (how big the movements are)
-Action selection (selecting appropriate actions to situation.
They also inhibit inappropriate movement (receive info from all sensory and motor and feedback to motor area)
What is the amygdala?
Relation to emotional understanding of threats.
What is the direct pathway for basal ganglia?
Pathway where the desired behaviours are passed back to the cortex (promoted)
What is the indirect pathway for the basal ganglia?
Pathway that inhibits undesired pathways (decides that programme is inappropriate).
What is the function of the substantia nigra?
Facilitates direct pathway and inhibits inappropriate motor commands (overall facilitation of movement).
What NT does the substantia nigra produce?
Dopamine.
What happens if dopamine stops being produced from the substantia nigra?
Scaling of movement is affected (difficult to initiate movements of the body- Parkinsons).
What is L-DOPA?
This can be given as medication and it is converted to dopamine in the brain- needed to make scaling more appropriate (after taking, walk better and swing arms etc).
How do basal ganglia influence motor activity?
-Action selection (facilitate/ suppress movement)
-Establish background patterns of movement
-Control and adjust posture
-Regulate scale/ intensity of motor output.
What is the function of the cerebellum?
This receives both sensory and motor and has a regulatory role (not directly contacting the LMNs).
What are the functional divisions of cerebellum?
-Vestibulocerebellum (from vestibular nuclei- balance)
-Spinocerebellum (posture, muscle tone, input from proprioceptors and output to motor centres in brain stem)
-Corticocerebellum (coordination and motor learning, input from motor cortex and output to motor cortex via thalamus).
What impact does the cerebellum have on motor control?
Compares what we want to do vs what we actually do (proprioceptors tell us where arm actually is and cerebellum can readjust until the goal is achieved).
What happens is there are cerebellar lesions?
-problems with balance and posture
-ataxia
-asynergia
-dysmetria
-scanning speech
-decomposition of movement
What is ataxia?
Abnormal or uncoordinated movements
What is asynergia?
Difficulty creating fluid motions
What is dysmetria?
Undershoot or overshoot- can’t judge scale of movements.
