PSY2061 Lecture Notes - Lecture 6: Dystonia, Pharmacotherapy, Premotor Cortex
5 Jun 2018
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PSY2061 – Lecture – Week 6 – The Control of Action
• movement is the only way we interact in our world and with others in our
world
• fundamentals
•
o at birth we have a limited behavioural repertoire - innate motor
programs
o during first 15 years of life our motor system develops through
o
▪ maturation of neuronal circuitry
▪ observation
▪ learning through different motor activities
o in addition to basic motor skills we also develop skilled motor
coordination
o neural subtracted expressed genetically, characteristic of our
species
• concept - movement control poses and faces a degrees of freedom
problem
•
o how is coordinated and controllable movement possible -
complexity
o what aspects of movement control are delegated by an executive
the brain?
o does delegation simply the control problem”?
o is all movement controlled?
o does does movement coordination also adhere to principles of self
organisation?
o
▪ not examinable
• movement control is exerted at separate and distinct levels - components
of the motor system
•
o muscles and motoneurons
o
▪ movement is the change in joint angle
▪ effected by a change in a state of muscle
▪ motor neurons cell bodies located along spinal cord and in
brain stem
▪
▪ axon to one muscle - innervates a number of muscle
fibres
▪ single motor neuron + muscle fibres = motor unit
▪ Motor neurones activated by
▪
▪ sensory afferent neurons - muscle spindels detect
lengthening of spinal cord - communicate this
change of state in the muscle
▪ interneurons - can change the way a motor neuron
(MN) functions
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▪ descending tracts from forebrain and brainstem
▪ alpha motoneurons (AMN)
▪
▪ originate spinal cord, exit via ventral root, terminate
in muscle
▪ action potential - acetylcholine - lead to muscle
contraction
o spinal cord
o
▪ mns innervate skeletal muscle
▪ first and final point for sensorimotor integration
▪ interneurons
▪ termination of descending pathways
▪
▪ direct/indirect synapses
▪ coordination of basic motor patterns
▪ central pattern generators
▪
▪ interneurons activate and inhibit specific
groups of mis in certain sequences
▪ protective reflexes, walking
o brainstem - medulla and midbrain
o
▪ swallowing, chewing, breathing, saccadic eye movements
o cortex
o
▪ primary motor cortex
▪ premotor cortex
▪ frontal eye fields
▪ parietal and prefrontal cortex are important for motor
control
▪
▪ apraxia
▪ loss of the ability to execute or carry out learned
purposeful movement
▪ common after damage to left hemisphere
▪ higher order motor deficits
▪
▪ presents bilaterally
▪ motor processes in tact
▪ common
▪ common classification
▪
▪ ideomotor apraxia
▪
▪ rough versions of desired action
▪ problem executing
▪ ideational apraxia
▪
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▪ can’t determine which actions are
necessary or their order
o supplementary motor complex
o
▪ role in planning, preparing and initiating movement
▪ important for sequencing
o basal ganglia
o
▪ receives inputs from cortex
▪ sends output to cortex
▪ no direct sensory inputs
▪ no direct output to spinal cord
▪ critical for movement control
▪
▪ initiation, selection and inhibition
o cerebellum
o
▪ inputs from cortex, brain stem and spinal cord
▪ pulpits to spinal cord motor cortex and oculomotor nuclei
▪ integration
▪ comparator
▪ well learned automatic movements
o primary motor cortex (m1)
o
▪ conscious, voluntary movement
▪ early stage learning
▪ distal - contralateral
▪ proximal muscle - bilateral control
• a minimum model for sensorimotor integration
•
o sensory receptor
o afferent pathway
o synapse onto alpha mn
o neuromuscular junction
• sensorimotor integration in the spinal cord - stretch reflects
•
o ef tendon tap
o autogenic
o monosynaptic
o muscle spindle - sensitive to the length of the muscle - increase in
firing of Ia afferent receptors - make monosynaptic connections
that report back to the same muscle - autogenic reflex - goes back
to the same place it came from
• components of the motor system
• brain stem
•
o physiological monitoring
o
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find more resources at oneclass.com
