Week Ten - Motor Systems Flashcards
How does the motor system work?
High level association areas (determine plans, goals of particular movement) interact with lower levels in the system that executes the motor commands and tell us whether the desired movement was achieved.
What are the 3 governing principles of the motor system?
1) Hierarchical and parallel organisation
2) Sensory input guides output (eg using info from receptors in muscles)
3) Nature and locus of control change with learning (thing can typically require conscious management become automatic as we learn)
What are the 2 major subcortical structures of the Motor System?
Basal Ganglia
Cerebellum
How do muscles work?
In agonistic pairs - they act under tension
What is the combination of an alpha motor neuron and muscle fibres referred to as?
Motor units
Muscles that we really need fine control over have?
Few muscle fibres in the muscle unit
Muscles that we don’t have fine control over have?
Many muscle fibres
Can you grade the amount of force that comes from a motor unit?
NO. they are either all or nothing
What are the 2 types of sensory receptor organs within the tendons and muscles?
Golgi Tendon Organs
Muscle Spindles
What are Golgi Tendon Organs?
They are embedded in tendons which connect muscle to the bone.
They deterch muscle tension
What are Muscle Spindles?
They are embedded in muscle tissue and detect changes in muscle length. They have their own muscle control system
Simple reflexes are controlled by?
Circuits in the spinal cord
A withdrawal reflex is not what?
Monosynaptic (does not provide direct communication between sensory and motor neurons innervating the muscle)
Explain the response of the body during a stretch flex
This is monosynaptic (direct communication between sensory and motor neurons innervating the muscle does occur)
How is the basal ganglia involved in motor control?
Once behaviours move away from higher order processing (become more automatic) it transfers to the BG
3 divisions in the Cerebellum?
Neocerebellum (outer layers & motor planning)
Spinocerebellum
Vestibulocerebellum (balance)
What happens if damage to the Cerebellum?
Problems adapting to novel situations. Movements can be too large or small and balance problems
Secondary motor areas (area 6) roles?
Takes signals from higher areas
Involved in the planning of movements and coordinating more complex ones
What is not required for action?
Sensory feedback (monkey experiment)
What is enpoint control?
The idea that movements are planned based on the final goal of the movement (not planning how to get there)
What do motor movements code for?
1) movement direction
2) muscle activity
What does a population vector provide?
Provides cortical representation of a movement
How can population vectors be used to control things in the human world?
Can control prosthetic limbs through brain activation patterns
Can control computer games
The basal ganglia is important for?
Movement and mediating response competition
Explain the Direct and Indirect pathways into the BG?
Direct: The accelerator. Inhibits the BG, thus there is less output onto the thalamus and greater drive to the Cortex.
Indirect: Applies the breaks. Excites the BG, thus BG has a greater inhibitory output onto the thalamus and less cortical drive
What happens if the direct and indirect pathways of the BG aren’t in balance?
Parkinson’s disease
Huntington’s disease
can be out of balance in both ways
BG problems affect what?
Amplitude control
Makes switching between tasks difficult
Dopamine and its role in learning motor skills?
Destroyed dopaminergic neurons in rats inhibited them from learning (they were not able to learn)
Once a dopamine injection, they were able to learn.
Suggesting dopamine is required for learning rather than consolidation
TMS and its effect on learning
TMS can be used to increase/decrease brain region activity
Motor cortex depressed through TMS - you do not get as much learning
What does movement adaptation require?
The same goals but different motor commands
Why does movement adaptation occur?
Due to error signals that are created through forward models (networks in the brain the predict the sensory consequences of a movement)
