Higher motor control

Question 1

what have synapses in the brainstem and are involved in motor neuron diseases?

Answer 1

brainstem motor nuclei

Question 2

what higher motor control area issues commands based on integration of sensory inputs via upper motor neurons?

Answer 2

the motor cortex

Question 3

how is motor information relayed from higher motor cortex to motor neurons?

Answer 3

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

Question 4

what is the main role of the motor cortex?

Answer 4

regulates activity in spinal cord circuits

Question 5

what issues happen as a result to damage to motor cortex?

Answer 5

poor coordination
weakness of movement
upper motor neuron syndrome

Question 6

what to do =

Answer 6

basal ganglia

Question 7

how to do it =

Answer 7

cerebellum

Question 8

group of nuclei connected in a circuit that links back to the motor cortex =

Answer 8

basal ganglia

Question 9

where do the nuclei of the basal ganglia lie?

Answer 9

deep within cerebral hemispheres

Question 10

the basal ganglia receives _______ input from many areas of the cortex from the chemical ______

Answer 10

excitatory, glutamate

Question 11

is the output from the basal ganglia > thalamus > motor cortex, mainly inhibitory or excitatory?

Answer 11

inhibitory

GABA > sends loads of inhibition to cortex to turn down different signals

Question 12

basal ganglia is widely studied in motor control but not fully understood. what is thought to be its overall function?

Answer 12

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

Question 13

what is the selection problem?

Answer 13

multiple command systems all distributed across brain in command all the time

Question 14

what are 3 features of command systems in the brain?

Answer 14

spatially distributed
processing in parallel
all act through final common motor path

Question 15

how does the basal ganglia overcome the selection problem if it can’t do more than 1 thing well at a time?

Answer 15

allows you to do what you NEED to do from a survival perspective

Question 16

how does the basal ganglia disinhibit the motor cortex?

Answer 16

burst of excitation in striatum > sends inhibition to global pallidus > allows thalamus and cortex to be temporarily disinhibited > increases excitation in lower motor neurons

Question 17

what chemical produces the transient burst of excitation that causes disinhibition?

Answer 17

dopamine

Question 18

brain area that allows motor control to be performed accurately =

Answer 18

cerebellum

Question 19

how is the cerebellum like a computer?

Answer 19

lots of sensory info coming into it and it feeds back into motor cortex

Question 20

what is similar about the basal ganglia and cerebellum in terms of projection?

Answer 20

there is no direct projection to lower motor neurons, instead modulates activity of upper motor neurons

Question 21

contains around half total number of CNS neurons and projects to almost all upper motor neurons =

Answer 21

cerebellum

Question 22

damage to the cerebellum results in poor control and coordination of movement called?

Answer 22

ataxia

Question 23

what parts of CNS input into the cerebellum?

Answer 23

spinal cord
cerebral cortex
PONS
vestibular system

Question 24

what parts output from cerebellum?

Answer 24

THALAMUS > motor cortex

Question 25

what information inputs into the cerebellum from the spinal cord?

Answer 25

proprioceptive info about limb position and movement (muscle spindles, other mechanoreceptors)

Question 26

what information inputs into cerebellum from the vestibular system?

Answer 26

rotational and acceleratory head movement