Higher motor control Flashcards
what have synapses in the brainstem and are involved in motor neuron diseases?
brainstem motor nuclei
what higher motor control area issues commands based on integration of sensory inputs via upper motor neurons?
the motor cortex
how is motor information relayed from higher motor cortex to motor neurons?
sensory info via upper motor neurons
copy sent to BASAL GANGLIA and CEREBELLUM which both feedback to cortex via the thalamus
command that reaches lower motor neurons is continually modulated by basal ganglia and cerebellum
what is the main role of the motor cortex?
regulates activity in spinal cord circuits
what issues happen as a result to damage to motor cortex?
poor coordination
weakness of movement
upper motor neuron syndrome
what to do =
basal ganglia
how to do it =
cerebellum
group of nuclei connected in a circuit that links back to the motor cortex =
basal ganglia
where do the nuclei of the basal ganglia lie?
deep within cerebral hemispheres
the basal ganglia receives _______ input from many areas of the cortex from the chemical ______
excitatory, glutamate
is the output from the basal ganglia > thalamus > motor cortex, mainly inhibitory or excitatory?
inhibitory
GABA > sends loads of inhibition to cortex to turn down different signals
basal ganglia is widely studied in motor control but not fully understood. what is thought to be its overall function?
selection device that switches between selected commands.
we need to move and have coordinated motor activity > need to do 1 command at a time
basal ganglia revolves competition between commands
inhibits behaviour output to prevent motor cortex from activating different activity that is not needed at the time
what is the selection problem?
multiple command systems all distributed across brain in command all the time
what are 3 features of command systems in the brain?
spatially distributed
processing in parallel
all act through final common motor path
how does the basal ganglia overcome the selection problem if it can’t do more than 1 thing well at a time?
allows you to do what you NEED to do from a survival perspective
how does the basal ganglia disinhibit the motor cortex?
burst of excitation in striatum > sends inhibition to global pallidus > allows thalamus and cortex to be temporarily disinhibited > increases excitation in lower motor neurons
what chemical produces the transient burst of excitation that causes disinhibition?
dopamine
brain area that allows motor control to be performed accurately =
cerebellum
how is the cerebellum like a computer?
lots of sensory info coming into it and it feeds back into motor cortex
what is similar about the basal ganglia and cerebellum in terms of projection?
there is no direct projection to lower motor neurons, instead modulates activity of upper motor neurons
contains around half total number of CNS neurons and projects to almost all upper motor neurons =
cerebellum
damage to the cerebellum results in poor control and coordination of movement called?
ataxia
what parts of CNS input into the cerebellum?
spinal cord
cerebral cortex
PONS
vestibular system
what parts output from cerebellum?
THALAMUS > motor cortex
what information inputs into the cerebellum from the spinal cord?
proprioceptive info about limb position and movement (muscle spindles, other mechanoreceptors)
what information inputs into cerebellum from the vestibular system?
rotational and acceleratory head movement
