basal ganglia

Question 1

what structures are involved in the neural control of movement?

Answer 1

brainstem and spinal cord
descending pathways
cerebellum
basal ganglia

Question 2

what is the function of the cerebellum?

Answer 2

sensory motor coordination of ongoing movement

Question 3

what is the function of the motor cortex?

Answer 3

planning, initiating and directing voluntary movement

Question 4

what is the function of the brainstem centres?

Answer 4

basic movements and postural control

Question 5

what are the basal ganglia?

Answer 5

caudate
putamen
globus pallidus

Question 6

what are the parts of the caudate?

Answer 6

globular head
tapering body
down curving tail

Question 7

where are the basal ganglia found?

Answer 7

cerebral cortex

Question 8

where is the caudate found?

Answer 8

from the frontal cortex to the temporal cortex

Question 9

what is the putamen attached to?

Answer 9

caudate head

Question 10

what are the parts of the globus pallidus?

Answer 10

internal and external segments

Question 11

what does the internal segment of the globus pallidus do?

Answer 11

sends output to the thalamus

Question 12

what does the external segment of the globus pallidus do?

Answer 12

relays info between the other basal ganglia nuclei and GPi

Question 13

what is the corpus striatum?

Answer 13

caudate

putamen

Question 14

what is the lentiform nucleus?

Answer 14

caudate

globus pallidus

Question 15

what is the internal capsule and what does it do?

Answer 15

white matter structure (myelinated fibres) – separates lentiform nucleus from caudate and thalamus

Question 16

what are the functions of the basal ganglia?

Answer 16

1. Movement – initiation, maintenance, inhibiting antagonistic movements and switching (stopping/starting movement)
2. Processing info – emotion, motivation and cognition

Question 17

what is the blood supply to the caudate?

Answer 17

middle cerebral

anterior cerebral

Question 18

what is the blood supply to the putamen?

Answer 18

middle cerebral

anterior cerebral

Question 19

what is the blood supply to the globus pallidus?

Answer 19

middle cerebral

anterior choroidal

Question 20

what is the blood supply to the internal capsule?

Answer 20

middle cerebral
anterior cerebral
anterior choroidal

Question 21

what gives input into the basal ganglia?

Answer 21

cerebral cortex

substantia nigra pars compacta

Question 22

what is the corticostriatal pathway?

Answer 22

pathway from cerebral cortex to the basal ganglia

Question 23

what is the nigrostriatal pathway?

Answer 23

pathway from the substantia nigra pars compacta

Question 24

what is the main neuron type in the corpus striatum?

Answer 24

medium spiny neurons

Question 25

what gives input into the corpus striatum and what type of input is it?

Answer 25

1. Cortical neurons (glutamatergic) 2. Substantia nigra pars compacta neurons (dopaminergic) 3. Local circuit neurons in corpus striatum (GABAergic inhibitory input)

Question 26

where do medium spiny neurons converge?

Answer 26

on GP and SNPR

Question 27

what is the corpus striatum output zone?

Answer 27

globus pallidus and substantia nigra pars reticulata

Question 28

what are the projections from the output zone to?

Answer 28

- subthalamic nucleus - VA/VL thalamic nuclear complex - superior colliculus

Question 29

where are the subthalamic nuclei?

Answer 29

under the thalamus

Question 30

what is the input into the subthalamic nuclei?

Answer 30

cerebral cortex and GPe

Question 31

what is the output from the subthalamic nuclei?

Answer 31

GPi and SNPR

Question 32

what is the input into the VA/VL thalamic nuclear complex?

Answer 32

GPi

Question 33

where does the VA/VL complex project to?

Answer 33

motor areas of the cerebral cortex

Question 34

what is the function of the superior colliculus?

Answer 34

controls eye movements

Question 35

what is disinhibition?

Answer 35

inhibition of inhibition | excitation by double inhibition

Question 36

what is the effect of the GP on the VA/VL complex at rest?

Answer 36

tonically inhibits it

Question 37

what is the function of the direct pathway?

Answer 37

allows basal ganglia to initiate movement

Question 38

what neurons do the corpus striatum and the GP mainly contain?

Answer 38

contain mainly inhibitory GABAergic neurons

Question 39

explain the direct pathway

Answer 39

* Activation of corpus striatum causes inhibition of GPi * GPi is tonically inhibiting the VA/VL complex of the thalamus * So, inhibition of GPi stops inhibition of the VA/VL thalamus complex * Motor cortex can be activated  initiation of movement

Question 40

what is the function of the indirect pathway?

Answer 40

• Antagonises direct pathway – stops movement initiation and terminates movements

Question 41

describe how the indirect pathway occurs

Answer 41

• A subset of nuclei in the corpus striatum receive inhibitory SNPC (D2) • Striatum then inhibits the GPe via inhibitory GABA neurons o GPe tonically inhibits the subthalamic nucleus • Activated subthalamic nucleus activates the GPi • GPi continues to inhibit VA/VL complex  cant transmit to the frontal cortex

Question 42

what part of the globus pallidus feeds into the subthalamic nucleus?

Answer 42

external segment

Question 43

during repetitive movements, are the direct and indirect pathways active or inactive?

Answer 43

``` direct = inactive indirect = active ```

Question 44

when is the direct pathway active?

Answer 44

when you want to change your motor program

Question 45

what receptors are expressed by the corpus striatum?

Answer 45

D1 or D2 dopamine receptors

Question 46

which pathway uses D1 receptor-expressing neurons?

Answer 46

direct

Question 47

which is stimulated by dopamine and what effect does it have - D1 or D2?

Answer 47

D1 | activates motor programme change

Question 48

which is inhibited by dopamine and what effect does it have - D1 or D2?

Answer 48

D2 | blocks motor programme change

Question 49

which pathway uses D2 receptor expressing neurons?

Answer 49

indirect

Question 50

what type of movement disorder is parkinsons?

Answer 50

hypokinetic

Question 51

what is parkinson's disease characterised by?

Answer 51

o Resting tremor o Slowness of movement (bradykinesia) o Muscular rigidity o Minimal facial expressions

Question 52

what causes parkinsons?

Answer 52

Caused by loss of dopaminergic neurons in SNPC which project to and innervate the corpus striatum

Question 53

what % of dopamine neurons have to degenerate before clinical symptoms show?

Answer 53

80%

Question 54

what change occurs to the parkinsons pathways?

Answer 54

Shift to indirect pathway – inhibition of the thalamus  decreased excitation of frontal cortex  decrease in movement

Question 55

how do you treat early parkinson's with cardinal symptoms but no medication related complications?

Answer 55

Levodopa Dopamine agonists MAO-B inhibitors

Question 56

how do you treat PD with motor and non-motor complications, medication side-effects and unrelieved symptoms?

Answer 56

COMT inhibitors Apomorphine Amantadine

Question 57

what type of movement disorder is huntington's?

Answer 57

hyperkinetic movement disorder

Question 58

how is huntington's inherited?

Answer 58

autosomal dominant

Question 59

which gene is affected in huntington's?

Answer 59

huntingtin gene

Question 60

what is huntington's characterised by?

Answer 60

o Mood alterations (e.g. depression) o Personality alterations (e.g. irritability, impulsive or eccentric behaviour) o Defects in memory and attention o Involuntary movements (hallmark of the disease)

Question 61

what is the hallmark of huntington's?

Answer 61

involuntary movements

Question 62

what causes the defects in motor function of huntington's?

Answer 62

due to the loss of GABAergic neurons in the corpus striatum, which project to and innervate the globus pallidus

Question 63

which pathway is the balance shifted to in huntington's?

Answer 63

direct pathway

Question 64

what is chorea?

Answer 64

rapid, involuntary, jerky-type movements

Question 65

what is athetosis?

Answer 65

slow, involuntary, smooth, writhing-type

Question 66

what is ballismus?

Answer 66

rapid, involuntary, wild flinging-type movements