Motor Modulation: Basal Ganglia & Cerebrebellum

Question 1

how does the basal ganglia and the cerebellum modulate motor movement?

Answer 1

Performing only ‘wanted’ movements, and no
‘unwanted’ movements
■ Motor ‘learning’ – improving movements with
practice
○ Coordinating timing between muscle groups to
produce fluid movements

Question 2

the basal ganglia is :

Answer 2

-a group of nuclei which initiate a collection of relevant movements for a given task
-inhibit competing movements for that task

Question 3

what is a motor program?

Answer 3

simple movement sequences are stored in our brains
BG accesses these stored memories and activates one and inactivates the other

Question 4

does the basal ganglia initiate movement?

Answer 4

no it acts more like a funnel or filter for movement

Question 5

what is the funnel/filter feature of the BG??

Answer 5

○ Funnel – receive information from many cortical areas, process it and output it to a few select structures
○ Filter – only movements appropriate to the task at hand are ‘selected

Question 6

BG neurons fire _____ a movement happens

Answer 6

before (planning)

Question 7

if you have a lesion of the BG what effect will the patient have?

Answer 7

disturbances in initiating movement

Question 8

other than the BG what else fires during the planning phase of movement?

Answer 8

premotor cortex and supplementary motor area

Question 9

at rest BG neurons _____ _____ the thalamus

Answer 9

tonically inhibit

Question 10

when movement is needed what happens?

Answer 10

the inhibition is transiently relieved

Question 11

BG acts on what?

Answer 11

thalamic nuclei

Question 12

what is the direct BG pathway?

Answer 12

go signal
DISINHIBITS stimulating wanted movements

Question 13

what is the indirect pathway?

Answer 13

stop signal
REINFORCES the inhibition stopping unwanted movement

Question 14

can the indirect and direct pathway ever work together?

Answer 14

yes often they work together to ensure intended movements are made

Question 15

what are the brain nuclei of the BG?

Answer 15

caudate, putamen, globus pallidus and subthalamic nucleus

Question 16

what brain stem nuclei are involved with the BG?

Answer 16

substantia nigra

Question 17

what are the input nuclei?

Answer 17

caudate and putamen (aka striatum)

Question 18

what is the cuadate?

Answer 18

C shaped nucleus that curves into multiple cerebral lobes

Question 19

what is the main input nucleus for motor movement?

Answer 19

putamen

Question 20

what is the most lateral aspect of the bg?

Answer 20

putamen (adjacent to the lateral fissure and insula)

Question 21

what is the main output for the BG?

Answer 21

globus pallidus

Question 22

The globus pallidus has two segments:

Answer 22

internal and external segment

Question 23

what does the internal segment of the GP do?

Answer 23

OUTPUTS motor info to direct and indirect pathways

Question 24

what does the external segment do?

Answer 24

modulatory projections to the subthalamic nucleus – indirect pathway

Question 25

the internal segment of the GP has high ___ activity, which has what effect?

Answer 25

high levels of tonic inhibitory activity acting to inhibit the thalamus in a resting state

Question 26

what is a modulatory nuclei?

Answer 26

only communicates with other nuclei in the BG GP, Stn, SsN

Question 27

At rest for the direct pathway, the ability of the thalamus to excite the cortex (and therefore initiate a motor program) is inhibited due to ________________

Answer 27

the tonic action of the GPi

Question 28

for the direct pathway For a motor program to be activated, activity of the ______ must be ______

Answer 28

GPi must be transiently inhibited

Question 29

the direct pathway ______

Answer 29

DISinhibits (allows)

Question 30

go over the flowcharts

Answer 30

direct/indirect

Question 31

At rest, striatal neurons are ________ and need to be __________

Answer 31

hyperpolarized, and need multiple excitatory inputs to reach firing threshold

Question 32

what causes Parkinson's?

Answer 32

associated with degeneration of dopaminergic neurons in the SN neurodegeneration of neurons in the direct pathway causing loss of stimulation of the striatum LOSS OF GO SINGAL

Question 33

what is the cardinal signs of Parkinson's?

Answer 33

TRAP tremor, rigidity, akinesia, postural change

Question 34

Cortical neurons excite the:

Answer 34

striatum

Question 35

Striatum inhibits ______________

Answer 35

Globus Pallidus internal segment

Question 36

Thalamus (now released from GPi inhibition) can _____ and _______

Answer 36

can fire and excite the motor cortex

Question 37

Which nuclei of the Basal Ganglia receive direct cortical input? A. Globus pallidus internal and external segments B. Caudate and putamen C. Substantia nigra and subthalamic nucleus

Answer 37

B. Caudate and putamen

Question 38

Within the direct pathway, the globus pallidus internal segment provides ______ input to the ________ A. Excitatory; thalamus B. Inhibitory; thalamus C. Excitatory; striatum D. Inhibitory; striatum

Answer 38

B. Inhibitory; thalamus

Question 39

Indirect pathway reinforces _____________________

Answer 39

inhibitory drive to the thalamus, repressing movement – especially targeted at unwanted movement (e.g. competing motor programs)

Question 40

One way to increase inhibitory drive to the thalamus is to provide ___________________

Answer 40

greater stimulus to the GPi, strengthening its signal

Question 41

the circuitry is set up such that the _________________ is tonically inhibiting the STN

Answer 41

globus pallidus external segment (GPe)

Question 42

Neurons of the striatum can inhibit the ______ to release the STN and allow it to fire

Answer 42

GPe

Question 43

in the indirect path Cortical neurons excite the _________

Answer 43

striatum

Question 44

in the indirect path Striatum inhibits _______________ (which now cannot inhibit subthalamic nucleus)

Answer 44

Globus Pallidus external

Question 45

what cases huntingtins disease?

Answer 45

degeneration of neurons in the striatum resulting in unwanted movements like chorea and rigidity

Question 46

what mnemonic is used for huntingtins?

Answer 46

CAGE

Question 47

Indirect pathway can be modulated by neurons of the _______________, which provide an inhibitory signal

Answer 47

substantia nigra

Question 48

Striatal neurons associated with direct pathway have _______ receptors that _________ in response to dopamine

Answer 48

D1 dopamine receptors, which depolarize a cell in response to dopamine

Question 49

Striatal neurons associated with indirect pathway have __________ receptors that _______ in response to dopamine

Answer 49

D2 dopamine receptors, which hyperpolarize a cell in response to dopamine

Question 50

________ can both excite the direct pathway and inhibit the indirect pathway

Answer 50

substantia nigra

Question 51

what is the function of the cerebellum?

Answer 51

Coordinates timing between different muscle groups to produce fluid movement -motor learning (improvement with practice) -feedforward (calculating others trajectories to avoid hitting into people in a crowded path)

Question 52

what happens if cerebellum becomes damaged?

Answer 52

loss of coordination... ATAXIA (lack of coordination between antagonist and agonist muscles, abnormal movement/trajectory)

Question 53

what is the cerebellums role in movement?

Answer 53

modifies commands it gets from the cortices to make the movement more accurate

Question 54

when does motor learning and error prediction tweaks occur?

Answer 54

Planning phase of movement (makes it more efficient)

Question 55

when does error correction occur?

Answer 55

executing movement phase

Question 56

what are the lobes of the cerebellum?

Answer 56

anterior, posterior and flocculonodular

Question 57

where is cerebellar grey matter located?

Answer 57

--external surface folds called folia --deep nuclei (dentate, emboliform, globose, fastigial)

Question 58

what is found on the inferior and superior cerebellar peduncles?

Answer 58

incoming and outgoing fibers

Question 59

what is found in the middle cerebellar peduncles?

Answer 59

incoming fibers only

Question 60

what makes up the cerebellar blood supply?

Answer 60

-superior cerebellar artery -anterior inferior cerebellar artery -posterior inferior cerebellar artery

Question 61

deep cerebellar nuclei are _____ structures of the cerebellum

Answer 61

output

Question 62

what occurs at the spinocerebellum?

Answer 62

error correction (detects difference between motor plan and execution and reduces difference)

Question 63

where does the spinocerebellum receive projections?

Answer 63

proprioceptors (muscle spindles and golgi tendon organs) inferior olive

Question 64

what does the paravermis and vermis control?

Answer 64

vermis: central body movement coordination paravermis: distal muscles

Question 65

what effect can happen from midline cerebellar damage?

Answer 65

loos of coordination of proximal muscles, affecting balance, posture and gait (truck ataxia and wide unsteady gait)

Question 66

what happens with lateral damage to the cerebellum?

Answer 66

movement deficits in IPSILATERAL extremity -loss of coordination- joints moving separately instead of smooth -inaccuracy in range and direction of movement -trouble with patterned movement

Question 67

what does the vestibulocerebellum do?

Answer 67

-corrections to stability and balance, both continuous and anticipatory -contributes to vestibular ocular reflex and smooth pursuit of eyes

Question 68

where does the vestibulocerebellum receive projections?

Answer 68

vestibular nuclei and vestibular ganglia -inferior olivary nucleus

Question 69

what is the output for the vestibulocerebellum?

Answer 69

vestibular nuclei reticular formation (bypasses DCN)

Question 70

what happens with floccular lobe syndrome?

Answer 70

truncal ataxia, nystagmus

Question 71

where does the cerebrocerebellum receive projections?

Answer 71

base of pons inferior olivary nucleus

Question 71

what is the function of the cerebrocerebellum?

Answer 71

motor learning, adapting motor programs to make future movements more accurate especially in distal extremities

Question 72

whee does the cerebrocerebellum output?

Answer 72

UMN of lateral movement path via VL of thalamus

Question 73

how does the cerebellum error correct?

Answer 73

deep cerebellar nuclei (excitatory) purkinje fibers (modulatory inhibition)

Question 74

what are the layers of cell interaction in the cerebellar cortex?

Answer 74

incoming mossy fibers granular cells purkinji cells

Question 75

155