Motor Control Flashcards
what is motor control
the ability to regulate or direct mechanisms essential to movement
what are you looking for when it comes to motor control?
- coordination of movements
- accuracy
- speed
- stability
- selectiveness
- smoothness of movements
What does motor control rely on?
Complex and coordinated interactions between various parts of the central nervous system
Are the three stages of motor control
Perception
Cognition
Action
Describe the perception stage of motor control
Sensing, perceiving, interpreting
Describe the cognition stage of motor control
Conceptualisation, strategy planning
Describe the action stage of motor control
Activation and execution
What do nociceptors detect?
pain
What do thermoreceptors detect?
Temperature changes
What do proprioceptors detect?
Movement
What is the job of receptors?
To detect information, which is then transmitted to the spinal cord via sensory nerves (afferent nerves)
What do muscle spindles detect?
Changes in muscle length
What do Golgi tendon organs detect
Tension in the muscle
What do both muscle spindles and Golgi tendon organ stimulate?
To reflex arc
what does the vestibular apparatus detect
- montion
- spatial orientation
- Head position
Where is auditory information sent?
Temporal lobe
Where is vision information sent
Occipital lobe
What is the somatosensory system?
Conscious perception of touch, pressure, pain, temperature, position, movement, and vibration
Describe the stretch reflex
- relies on muscle spindle information
- is triggered when a muscle is lengthened
- it is designed to prevent overstretching of the muscle by causing reflex contraction of the length and muscle
how does stretch reflex occur
- in the spinal cord, the sensory impulses directly excite a single motor and you’re on leading to the agonist muscle
- the sensory impulses also stimulates an inhibitory association neuron in the spinal cord. This neuron inhibits the mating neuron, leading to the antagonist.
- reciprocal innovation results when the stretching muscle in the opposing muscle relaxes
Describe the tendon reflex
- relies on Golgi tendon organ information
- is triggered when tension is building up.
- this is designed to prevent hearing of a muscle by causing a reflex relaxation of the muscle
Explain how the tendon reflex works
- receptors respond to muscle tension via the Golgi tendon organ
- increased tension stimulates receptors which increases nerve impulses to the spinal cord
- this causes the muscle to relax by decreasing the nerve impulses to the spinal cord, so inhibits the agonist and activates the antagonist
How is sensory information, processed and refined before sending to the motor cortex and muscles
Done through the cortical association area:
- sensory processing in the thalamus
- basal ganglia
- Cerebellum
What happens once a movement is planned
It is supplied as a signal in a feedforward manner to be executed
What happens once a movement has started
Receptors can provide feedback about the movement and allow for signals to be altered and refine the movement
Which part of the brain plays an important role in relaying sensory information to the cerebral cortex
The thalamus
Where is sensory information organised
In the sensory homunculus
What are the different roots of the basal ganglia?
Direct pathway (excitatory)
Indirect pathway (inhibits, unwanted movement)
What is the basal ganglia influenced by?
Dopamine
What is the basal ganglia involved in?
- planning and control of complex motor behaviour
- initiating movement through outputs to supplementary motor areas
- prevents unwanted movements
Why does death of dopamine containing cells in the brain cause Parkinson’s disease symptoms?
There’s not enough dopamine to regulate the direct and indirect pathways which causes an unbalanced
Why is the cerebellum described as having an “auto pilot function”
Cerebellum continually compares the higher brains intention with the bodies performance and send out messages to initiate the appropriate corrective measures, e.g. take longer step to avoid tripping
What does the cerebellum control?
- balance
- coordination
- correction of movement
- comparator
What symptoms might you observe in someone with cerebellar damage?
- balance problems
- gait disorders
- difficulties in coordination resulting in ataxia
- uncoordinated movements
- imbalance
- speech problems(dysarthria),
- visual problems (nystagmus)
- vertigo as a part of the vestibulocerebellar system.
What is the role of the premotor cortex?
Assist with proximal, preparation and control of distal movements (e.g.shoulder movement for reaching to grasp objects)
What is the role of the supplementary cortex?
- coordinates bilateral movements e.g. clasping hands
- assist in assembly of central motor programs
What is the role of the motor cortex?
- it’s interacts with sensory processing areas, basal ganglia, and cerebellum, to identify where we want to move, to plan the movement and execute our actions
- it initiates movements on contralateral
What symptoms you observe in someone with motor cortex damage?
- Weakness or paralysis
- Impaired coordination
- Spasticity
- Loss of voluntary movement control
- exaggerated or diminished reflex responses.
What are spinal tracts
Your pathways within the spinal cord that carry information to, and from the brain/body
What is an ascending spinal tract?
Sensory pathways that carry somatic sensory information up to the brain
What is a descending spinal tract?
Motor pathways that send information from the brain to the spinal cord
What are the three conscious ascending spinal tracts
- fasciculus cuneatus (supplies proprioception and vibration info to lower limbs)
- gascuculus gracilis (supplies proprioception and vibration info to upper limbs)
- spinothalamic tract (pain, temperature, pressure info)
What is the unconscious ascending spinal tract?
Spinalcerebellar
What are the pyramidal descending spinal tracts?
pyramidal tract: in cerebral cortex - conscious control of movement
- corticospinal: fine, skilled, consious movement (helps produce output via motor cortex)
- corticobulbar: movements of the face
describe the extrapyramidal descending spinal tracts
extrapyramidal (in brainstem - unconscious control of movement)
- vestibulo spinal: increase extensor tone, inhibits flexor tone
- rubrospinal - decreases extensor tone, inhibits flexor tone
- recticulo spinal: regulation of vuluntary movement
- tectospinal - postural adjustments to visual stimuli
How are motor programs learned and refined?
Repetitive use
Explain how most programs are learned and refined
- ongoing movement is detected by proprioceptors muscles and joints and feedback control allows corrections to be made whenever of the outcome does not match the goal
- overtime this feedback will influence feedforward signals designed by the cortex
What are features of the early cognitive phase of motor learning?
- trial and error
- repetition
- performance-based focus
- person needs to work out what’s relevant and organise a movement pattern that leads to successful task completion
- multiple regions involved: cerebellum, visual and pre-frontal cortices
- extrinsic feedback – hands-on, verbal, visual
What are the features of the autonomous phase of motor learning?
- automatic
- Motor programs are stored
- Cognitive demand decreases
- effortless
- primarily motor cortex
- intrinsic feedback
What are the features of the associative phase of mator learning?
- Learning how to perform a skill, refining and adapting
- intrinsic feedback
- more outcome based
Define Neuroplasticity
The ability of the brain and nervous system to change structurally and functionally as a result of input from the environment.
RELEARNING
How does Neuroplasticity occur?
Neurons in the brain sprout and form synapses.
A
s the brain processes, sensory information frequently use synapses are strengthened, while unused synapses are weakned
What is synaptogenesis?
The formation of synapses
What are the principles of Neuroplasticity?
- Use it or lose it: you’re all connections lose strength when they are not being used
- Use it and improve it.: neural pathways grow stronger than more they are used
- Specific: your brain forms a specific circuitry response to specific activities
- Salience Matters: brain exercises must be meaningful to you in order to yield lasting change
- Transference: working to improve one skill may transfer its benefits to enhancing others
- Interference: neuroplastic changes that result from maintaining a bad habit can interfere with learning and adopting a new good habit
- Time matters: it takes avrying amounts of time for the brain to change depending on how complex or foreign the new behaviour or skill is to you
- Age matters: younger brains are more plastic but neurogenesis and plasticity continue at any age and phase of life
- Repitition matters: consistency is the key to building new synapses and solidifying new skills
- Intensity matters: neuroplstic changes result from incremental progressive challenges to elicit a positive growth response
what are some key principles on how we can influence motor learning
- increase feedback
- proprioceptive input
- facilitation
- normal movement
- repitition and practice
- whole and part task practice
consider the individual, task and environment - keep it functional
how is motor movements controlled
- cerebrum and basal ganglia are essential for successful motor performance
- they project directly into upper motor neurons
- these upper motor neurons then project to lower motor neurons which then stimulate muscle activity
- continual sesnory feedback is provided to inform the brain about the bodies position and movement
where are upper motor neurons located
cerebral cortex and brainstem
what are upper motor neurons
first order neurons which are responsible for carrying the electrical impulses that initiate and modulate movement.
what do upper motor neurons synapse directly onto
lower mototr neurons
what are lower motor neurons
transmit impulses via spinal peripheral nerves or cranial nerves to skeletal muscles
what are the 3 types of lower motor neuron and what target do they innervate
- branchial - cranial nerves
- visceral - autonomic nervous system (smooth muscle and glands)
- somatic - skeletal muscle
what do upper motor neurons excite
alpha and gamma motor neurons
what are the negative problems of upper motor neurons
lack of excitation means less stimulus to the lower motor neurons and therefore less/ no activity
leads to:
- weakness
- sensory loss
- hypotonia
- fatigue
what are the positive probelms of nupper motor neurons
excition with reduced inhibition
so
- inscreased tone
- hyperreflexia
what is spasticity
abnormally high muscle tone, which often affects antagonistic muscle groups
what is spasticity dependent on
amplitude and velocity
speed and force
how is spasticity best assessed
using rapid movements of the relevant joint to effect muscles involved.
when a threshold velocity, angle, or amplitude is reached then a sudden increase in tone can be detected as a characteristic ‘catch’
how is spasticity shown in upper limbs
affects flexors
how is spasticity shown in the lower limbs
affects extensors
what are common adult spasticities in the upper limb
flexed elbow
clenched fist
flexed wrist
what are common adult spasticities in the lower limb
equinivarus foot
plantar flexed foot or ankle
flexed toes
define rigidity
where the increased tone remains constant throught the range of moevement
how can rigidity be detected
can be detectable with very slow movements
in what muscles is rigidity present
equally present in flexor and anxtensor muscles so has a ‘uniform quality’ in all directions so is often refered to lead-pipe rigidity
why can there be cogwheeling type of rigidity
rigidity frequently rises in diseases of the basal ganglia so a tremor can coexist
