Basal Ganglia and Dopamine

Question 1

does the basal ganglia directly synapse with LMNs?

Answer 1

no

Question 2

what are the 5 nuclei of the basal ganglia?

Answer 2

1. Caudate
2. Putamen
3. Globus pallidus (internal/external)
4. substantia nigra
5. sub thalamic nucleus

Question 3

what pathway is the globus pallidus external?

Answer 3

indirect pathway

Question 4

what pathway is the globus pallidus internal?

Answer 4

direct pathway

Question 5

what structures forms the striatum?

Answer 5

caudate and putamen

Question 6

what are the 2 parts of the substantia nigra?

Answer 6

substantia nigra pars compacta
substantia nigra pars reticulata

Question 7

where do major inputs to the basal ganglia come from?

Answer 7

cerebral cortex

Question 8

where do almost all inputs synapse with in the basal ganglia?

Answer 8

the striatum

Question 9

where in the basal ganglia are most major outputs coming from?

Answer 9

globus pallidus internal
substantia nigra pars reticulata

Question 10

are the main output pathways from the basal ganglia excitatory or inhibitory?

Answer 10

inhibitory (GABAergic)

Question 11

where are the main targets for major outputs?

Answer 11

thalamus
reticular formation
superior colliculus

Question 12

what is inhibition?

Answer 12

When a neuron inhibits another neuron meaning it cannot be excited by a different neuron

Question 13

what is disinhibition?

Answer 13

when a neuron inhibits another neauron meaning that neuron cannot inhibit the next neuron so that neuron then gets excited (disinhibition=excitation)

Question 14

what is another name for the hyperdirect pathway?

Answer 14

stop pathway

Question 15

what is the function of the hyperdirect pathway?

Answer 15

it supresses ongoing movement

Question 16

what is another name for the direct pathway?

Answer 16

go pathway

Question 17

what is the function of the direct pathway?

Answer 17

initiation of movemnt

Question 18

what is another name for the indirect pathway?

Answer 18

no-go pathway

Question 19

what is the indirect pathway?

Answer 19

supression of unwanted competing movements

Question 20

what gets inhibited in the hyperdirect pathway?

Answer 20

the internal globus pallidus inhibits the thalamus

Question 21

what gets inhibited in the direct pathway?

Answer 21

the thalamus is less inhibited (disinhibited) therefore movement is initiated

Question 22

what gets inhibited in the indirect pathway?

Answer 22

the subthalamic nucleus stimulates the internal globus pallidus which inhibits the thalamus

Question 23

what is the function of the substantia nigra pars compacta?

Answer 23

It modulates activity of both the
direct and indirect pathways
through dopamine release
(dopaminergic pathway

Question 24

what is the function of the D1 receptors in the striatum?

Answer 24

Makes the direct pathway more active
(less inhibition to the thalamus)

Question 25

what is the function of the D2 receptors in the striatum?

Answer 25

Makes the indirect pathway less active (less inhibition to the thalamus)

Question 26

what is the net effect of the D1 and D2 receptors?

Answer 26

less inhibition of the thalamus

Question 27

what does it mean that the effects of dopamine are transient?

Answer 27

the increased excitation to the cortex in the direct and indirect pathway occurs in concert with selection of a movement

Question 28

what does the basal ganglia form a motor loop with?

Answer 28

the motor cortex in the same cerebral hemisphere

Question 29

what is the function of the prefrontal loop?

Answer 29

Initiation and termination of cognitive processes

Question 30

what is the function of the limbic loop?

Answer 30

Regulates emotional and motivated behaviour Transitions from one mood state to another

Question 31

what is an example of a hyperkinetic disorder?

Answer 31

Huntington's disease Hemiballismus

Question 32

what is an example of a hypokinetic disorder?

Answer 32

Parkinson's Disease

Question 33

what is a hyperkinetic disorder?

Answer 33

insufficient inhibition of the thalamus

Question 34

what is a hypokinetic disorder?

Answer 34

excessive inhibition of the thalamus

Question 35

where do clinical signs of a lesion to the basal ganglia typically present?

Answer 35

impairments on the contralateral side of the body

Question 36

what causes Huntington's disease?

Answer 36

Selective atrophy of the caudate and putamen

Question 37

what pathway is affected first in Huntington's disease?

Answer 37

indirect pathway

Question 38

what happens to the pathways in Huntington's disease?

Answer 38

the indirect pathway is underactive so eventually the direct pathway becomes overactive

Question 39

since both the direct and indirect pathways are affected in Huntington's what does this result in?

Answer 39

less tonic inhibition of the thalamus

Question 40

what brain structure has a lesion leading to hemiballismus?

Answer 40

subthalamic nucleus

Question 41

what is a symptom of hemiballismus?

Answer 41

involuntary flinging of the limbs

Question 42

which side of the body is affected by hemiballismus?

Answer 42

the side contralateral to the damage

Question 43

what is the cause of Parkinson's?

Answer 43

Progressive degeneration of dopaminergic neurons in Substantia nigra pars compacta

Question 44

what are the symptoms of Parkinson's?

Answer 44

T- Tremor R- rigidity A-akinesia P- postural instability

Question 45

what pathways are affected in parkinson's disease?

Answer 45

both direct and indirect

Question 46

what occurs in the D1 pathway with parkinson's?

Answer 46

there is less D1 facilitation increased inhibition to the thalamus leading to decreased movement

Question 47

what occurs in the D2 pathway with Parkinson's?

Answer 47

less D2 facilitation excessive inhibition of the thalamus

Question 48

what is the net effect of dopamine loss?

Answer 48

inhibition of the thalamus

Question 49

what is Parkinson's disease treatment?

Answer 49

a supplement/replace dopamine called L-dopa which is a dopamine precursor

Question 50

what can't cross the blood-brain barrier?

Answer 50

dopamine

Question 51

what are dyskinesias?

Answer 51

involuntary movements

Question 52

what is 'wearing off'?

Answer 52

predictable decline in function

Question 53

what are on-off fluctuations

Answer 53

Unpredictable changes in motor function

Question 54

what does deep brain stimulation to treat parkinsons's target?

Answer 54

Globus Pallidus internal segment Subthalamic nuclei