Basal Ganglia

Question 1

Basal Ganglia- movement

Answer 1

Regulate intensity of slow or stereotypes movements
Inhibit antagonistic + unnecessary movements
Switch motor programmes (stop or start)

Question 2

Neural structures in basal ganglia

Answer 2

Caudate nucleus
Putamen
Globus pallidus

Question 3

Caudate nucleus

Answer 3

C shaped nuclei in frontal lobe

Head region curves + extends to form elongated body, tapering at tail and ending in temporal lobe

Question 4

Putamen

Answer 4

Large, rounded nuclei located in forebrain

Connected to caudate nucleus at head region of caudate

Question 5

Globus pallidus

Answer 5

Pale body
Internal segment (GPi) --> output to thalamus
External segment (GPe) --> relays info between other basal ganglia nuclei + internal globus pallidus

Question 6

Internal capsule

Answer 6

White matter structure

Separates lentiform nucleus + caudate nucleus

Question 7

Caudate nucleus blood supply

Answer 7

Middle cerebral artery (body)

Anterior cerebral artery (anterior)

Question 8

Putamen blood supply

Answer 8

Middle cerebral artery

Anterior cerebral artery (anterior)

Question 9

Globus pallidus

Answer 9

Middle cerebral artery

Anterior choroidal

Question 10

Internal capsule

Answer 10

MCA (middle)
ACA (anterior limb)
Anterior choroidal (posterior limb)

Question 11

Neuronal projections into basal ganglia are from

Answer 11

Cerebral cortex

Substantia nigra pars compacta

Question 12

Cerebral cortex projections

Answer 12

Almost all project directly to caudate + putamen
Majority from frontal + parietal
–> projections referred to as corticostriatal pathway

Question 13

Substantia nigra pars compacta projections

Answer 13

Located in midbrain
Dopaminergic input to caudate nucleus + putamen
–> progressions referred to as nigrostriatal pathway

Question 14

Input zone of basal ganglia

Answer 14

Corpus striatum- caudate nucleus + putamen

Question 15

Corpus striatum neurones

Answer 15

75% medium spiny neurones

Question 16

Inputs to medium spiny neurones

Answer 16

Cortical neurones (glutamatergic)
Substantia nigra pars compacta neurones (dopaminergic)
Local circuit neurones within corpus striatum (GABAergic)

Question 17

Axons arising from medium spiny neurones converge on

Answer 17

Neurones in globus pallidus + substantia nigra pars reticulata

Question 18

Medium spiny neurones input

Answer 18

Cortical + Substantia nigra pars compacta + Corpus striatum –> medium spiny neurones –> globus pallidus + substantia nigra pars reticulata

Question 19

Output zone of basal ganglia

Answer 19

Globus pallidus

Substantia nigra pars reticulata

Question 20

Output zone projections

Answer 20

Subthalamic nucleus
VA/VL thalamic nuclear complex
Superior colliculus –> eye movements

Question 21

Subthalamic nucleus

Answer 21

Small paired nuclei below thalamus
Input from cerebral cortex + GPe
Projects to GPi and substantia nigra pars compacta

Question 22

VA/VL thalamus complex

Answer 22

Input from GPi

Projects to motor areas of cerebral cortex

Question 23

Direct pathway

Answer 23

Means for Basal ganglia to facilitate initiation of volitional movement

Question 24

Direct pathway MOA

Answer 24

Excitatory glutamate axons project from sensory + association cortices to caudate + putamen
–> project to GPi (inhibitory)
GPi projects to motor thalamus (inhibitory)
–> disinhibition as two negatives in a row
This then projects to motor thalamus + back to supplementary motor cortex

Question 25

indirect pathway

Answer 25

Antagonise activity of direct pathway | Stops movement

Question 26

Indirect pathway MOA

Answer 26

Output from caudate + putamen goes to GPe and subthalamic This then goes to GPi Subthalamic excitatory input to GPi tonic inhibitory action increases inhibition to motor thalamus --> motor cortex output from motor thalamus remains fixed

Question 27

Rest or doing repetitive movement

Answer 27

Direct pathway inactive | Indirect pathway active

Question 28

Change in movement

Answer 28

Direct pathway active | Indirect pathway inactive

Question 29

D1 receptor

Answer 29

Increases cAMP Increases sensitivity in corpus striatum neurones to glutamate Projects to GPi directly via direct pathway Activated by dopamine

Question 30

D2 receptor

Answer 30

Decreases cAMP | Depressed by dopamine

Question 31

Direct pathway receptor

Answer 31

D1

Question 32

Indirect pathway receptor

Answer 32

D2

Question 33

Parkinson's

Answer 33

Hypokinetic | Over 80% of dopaminergic neurones have to degenerate before clinical signs of disease manifest themselves

Question 34

Early PD

Answer 34

Levodopa Dopamine agonist MAO-B inhibitors

Question 35

PD with motor + non-motor complications

Answer 35

COMT inhibitors Apomorphine Amantidine

Question 36

Advanced PD

Answer 36

DBS

Question 37

Huntingtons

Answer 37

Hyperkinetic Autosomal dominant Involuntary movements Loss of GABAergic neurones in corpus striatum

Question 38

Chorea

Answer 38

Rapid, involuntary, jerky-type movements

Question 39

Athetosis

Answer 39

Slow, involuntary, smooth, writhing type movements

Question 40

Ballismus

Answer 40

Rapid, involuntary, wild flinging-type movements

Question 41

Huntingtons management

Answer 41

Amantidine- dystonia, apathy Benzodiazepine- anxiety Haloperidol- psychosis Olanzapine- weight loss