Basal Ganglia

Question 1

What are the 3 roles of the basal ganglia in movement?

Answer 1

1) Normal initiation of movement
2) Control of movement
3) Cessation of movement

Question 2

The basal ganglia gives output to the cerebral cortex via what structure?

Answer 2

Thalamus

Question 3

In what 2 opposing ways can the basal ganglia influence the cerebral cortex?

Answer 3

1) Excite the cerebral cortex

2) Dampen the cerebral cortex

Question 4

Lesions of the basal ganglia lead to what symptoms?

Answer 4

Dyskinesia

Question 5

What 5 structures make up the basal ganglia?

Answer 5

1) Caudate nucleus
2) Putamen
3) Globus pallidus
4) Amygdala
5) Claustrum

Question 6

What 2 structures make up the lentiform nucleus?

Answer 6

Globus pallidus and putamen

Question 7

What are the 2 subdivisions of the corpus striatum?

Answer 7

Neostriatum (striatum) and paleostriatum

Question 8

What 2 structures make up the striatum?

Answer 8

Caudate nucleus and the putamen

Question 9

What structure makes up the paleostriatum?

Answer 9

Globus pallidus

Question 10

What 3 structures make up the corpus striatum?

Answer 10

1) Globus pallidus
2) Putamen
3) Caudate nucleus

Question 11

Where is the amygdala located?

Answer 11

Front of the temporal lobe

Question 12

Where is the external capsule located?

Answer 12

Lateral to the putamen

Question 13

Where is the claustrum located?

Answer 13

Slither of grey matter lateral to the external capsule

Question 14

The basal ganglia develops from what kind of grey matter?

Answer 14

Telencephalic grey matter

Question 15

What 2 structures act functionally with the basal ganglia?

Answer 15

1) Subthalamus

2) Substantia nigra

Question 16

What 2 parts can the globus pallidus be subdivided into?

Answer 16

Globus pallidus interna and externa

Question 17

What 2 parts can the substantia nigra be subdivided into?

Answer 17

Pars compacta

Pars reticulata

Question 18

What is significant about the cells of the pars compacta?

Answer 18

Contain melanin

Question 19

The pars reticulate acts functionally with what part of the basal ganglia?

Answer 19

The globus pallidus interna

Question 20

In addition to its roles in movement, the basal ganglia is involved in what 2 other functions?

Answer 20

1) emotion

2) cognitive processes

Question 21

Neurons originating in the cerebral cortex act on what part of the basal ganglia, are they inhibitory or excitatory?

Answer 21

Cerebral cortex acts on the striatum (caudate nucleus and putamen)
Neurons are excitatory

Question 22

Neurons originating in the striatum act on what 2 structures, are they inhibitory and excitatory?

Answer 22

Striatum acts on globus pallidus interna and substantia nigra pars reticulate
Neurons are inhibitory

Question 23

Neurons originating in the globus pallidus interna and substantia nigra act on what structure, are they inhibitory or excitatory?

Answer 23

Globus pallidus interna and substantia nigra pars reticulata act on the thalamus
neurons are inhibitory

Question 24

Are the connections between the thalamus and cerebral cortex in the basal ganglia circuit, excitatory or inhibitory?

Answer 24

Excitatory

Question 25

Neurones from the thalamus in the basal ganglia circuit tend to project to which area of the cortex?

Answer 25

Premotor and supplementary motor areas

Question 26

After input from the basal ganglia, the motor cortex influences LMNs in which 2 ways?

Answer 26

1) Directly via the corticospinal pathway

2) Indirectly via connections to the brainstem centers from which UMNs arise (ie. reticulospinal pathway)

Question 27

In what 2 ways do the basal ganglia influence movements by which 2 pathways?

Answer 27

1) Direct pathway - facilitate behaviour and movements that are required and appropriate
2) Indirect pathway - inhibit unwanted behaviour and movements

Question 28

The direct pathway of the basal ganglia involves what 4 structures, what is the net result?

Answer 28

1) Cortex
2) Striatum
3) Globus palidus interna and substanita nigra pars reticulata
4) Thalamus
Net result is excitation of the cortex via the thalamus

Question 29

The indirect pathway of the basal ganglia involves what 6 structures, what is the net result?

Answer 29

1) Cortex
2) Striatum
3) Globus pallidus externa
4) Subthalamic nucleus
5) Globus pallidus interna and substantia nigra pars reticulata
6) Thalamus
Net result is lack of stimulation of cortex via inhibition of the thalamus

Question 30

Using flexing fingers as an examples, depict the role of the direct and indirect pathway?

Answer 30

Direct pathway causes you to contract flexors

Indirect pathway causes you to relax extensors

Question 31

What is the main functions of the substantia nigra pars compacta?

Answer 31

To initiate movement

Question 32

What substance is released by the substantia nigra pars compacta?

Answer 32

Dopamine

Question 33

What are the 4 main effects of basal ganglia damage?

Answer 33

1) Disordered movement (not paralysis) on the contralateral side
2) Slow movement (hypokinesia) - cant initiate movement
3) Rigidity
4) Tremor

Question 34

What effect does the substantia nigra have on the direct and indirect pathways of the basal ganglia?

Answer 34

Excites the direct pathway

Inhibits the indirect pathway (removing the inhibition, therefore excites)

Question 35

Via what kind of dopamine receptors does the substantia nigra act on the direct pathway?

Answer 35

D1 (excitatory)

Question 36

Via what kind of dopamine receptors does the substantia nigra pars compacta act on the indirect pathway?

Answer 36

D2 (inhibitory)

Question 37

Is Parkinsons disease a hypo or hyperkinetic disorder?

Answer 37

Hypokinetic disorder

Question 38

How does parkinsons disease affect the basal ganglia pathway?

Answer 38

Have loss of dopaminergic neurones from the SN pars compacta thus cannot excite the direct pathway or inhibit the inhibitory pathway so cannot initiate movement

Question 39

Parkinsons disease is said to affect what input of the basal ganglia?

Answer 39

The nigrostriatal input

Question 40

What is chorea?

Answer 40

Unwanted movements

Question 41

Is Huntingtons, a hypo or hyperkinetic disease?

Answer 41

Hyperkinetic

Question 42

What 2 degenerative changes can lead to a hyperkinetic disease such as Huntingtons?

Answer 42

1) Degeneration of subthalamic nucleus (excitatory to the globus pallidus)
2) Degeneration of inhibitory fibres from the striatum to globus pallidus in the indirect pathway

Question 43

Do hyperkinetic disorders tend to affect the indirect or direct pathway of the basal ganglia?

Answer 43

Indirect