PHYS20008 Lecture Notes - Lecture 9: Alpha Motor Neuron, Golgi Tendon Organ, Cerebral Cortex
10 May 2018
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Lecture 9
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- Reflex takes no planning, simplest, no requirement of cerebral cortex in order to
function properly, most bumps straight into spinal cord or brainstem at most and then
back out, reflex pathway is very simple and basic
- Voluntary: involves a lot more planning, time to think about what we are going to do,
executing a particular movement, involves cerebral cortex because involves thinking
about and strategising about the movement before execution, like playing piano
- Rhythmic: a series of motions that are integrated by rhythm generators within spinal
cord and brainstem that are executed automatically, input from cerebral cortex is
required for two aspects of that movement, walking (only think about start and stop,
everything in between is subconsciously processed by rhythm generators, don’t think
about walking)
- Voluntary movement: three phases: planning (about to execute sth), initiation (brain
puts together what needs to be executed and what do we need to do in terms of
motor control in order to execute that maneuver), execution (things are sent out to
alpha motor neurons and muscles are manipulated in such a way to execute that
particular movement)
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- Voluntary: need to recruit the cortex
- Idea feeds into cortical association areas → communicates with motor cortex
- Basal nuclei/ganglia: involves things responsible for movement, closely tied in with
thalamus (communicating with all the sensory info into us, need to be aware of
environment around us before executing movement), responsible for emotion and
reward behaviour, people with depression and anxiety (part of basal ganglia called
striatum → (normal) lights up because of positive words, reward center, dies down if
negative words; (depression) striatum lights up with negative words, dies down with
positive words), substantia nigra related to Parkinson’s disease (excess dopamine,
big problem with initiation of rhythmic movement, hard to start and stop walking)
- Initiation happens in motor cortex: sends signals down to alpha motor neurons →
initiate movement in muscle
- Cerebellum: maintain balance, involved in learnt behaviours and fine motor control
(e.g. writing, playing piano)
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find more resources at oneclass.com
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- Initiate a movement that disturbs posture → reflex that helps you maintain postural
changes despite what you’re doing to keep balance, upright etc; eye movement
tracking around etc don’t recruit cortex, simple action-reaction, a lot processed in
spinal cord as high up to brainstem involving cerebellum → delivered through
thalamus and onto cortex
find more resources at oneclass.com
find more resources at oneclass.com
