L14 - Basal Ganglia

Question 1

what is the function of the basal ganglia?

Answer 1

initiation, control and cessation of movement (motor response) 1. Excite cerebral cortex: facilitate wanted movement 2. Dampen cerebral cortex: inhibition unwanted movement

Question 2

a lesion of the basal ganglia results in what condition?

Answer 2

Dyskinesia abnormal, involuntary movements

Question 3

which nuclei make up the basal ganglia?

Answer 3

caudate nucleus putamen globus pallidus substantia nigra subthalamic nuclues

Question 4

what is the embryological origin of the corpus striatum?

Answer 4

telencephallic

Question 5

what is the embryological origin of the caudate nucleus?

Answer 5

telencephallic

Question 6

what is the embryological origin of the globus pallidus?

Answer 6

telencephallic

Question 7

what makes up the corpus striatum?

Answer 7

neostriatum: - caudate nucleus - putamen paleostriatum: - globus pallidus

Question 8

what is the embryological origin of the substantia nigra?

Answer 8

mesencephalic

Question 9

what is the embryological origin of the subthalamic nucleus?

Answer 9

diencephalic

Question 10

what are the 4 divisions of the diencephalon?

Answer 10

• thalamus - epithalamus - hypothalamus - subthalamus

Question 11

why does the substantia nigra have a black appearance?

Answer 11

holds melanin

Question 12

briefly describe the circuitry pathway of the basal ganglia-cortex?

Answer 12

cortex -> input nuclei (caudate and putamen = striatum) -> output nuclei (GPi and Sar) -> Thalamus -> cortex

Question 13

which are the receiving areas for afferent connections of the basal ganglia?

Answer 13

Striatum (caudate and putamen)

Question 14

what are corticostriatal fibres?

Answer 14

afferent fibres from the cortex - contain information about intended movement - excitatory

Question 15

what are striatonigral fibres?

Answer 15

afferent fibres from the substantia nigra - release dopamine (effect is inhibitory or excretory depending on the type of receptor)

Question 16

which type of fibres within the basal ganglia release dopamine? what affect does dopamine have?

Answer 16

striatonigral fibres (effect is inhibitory or excretory depending on the type of receptor)

Question 17

which structures are the “output nuclei” of the basal ganglia?

Answer 17

GPi + SNr These areas send efferent fibres to supply the thalamus

Question 18

what are Pallidothalamic fibres?

Answer 18

• inhibitory - inhibit thalamus

Question 19

what are Thalamocortical fibres?

Answer 19

• excitatory - facilitate movement

Question 20

with reference to the default pathway, the thalamus is under chronic inhibition by which fibres?

Answer 20

Pallidothalamic fibres

Question 21

with reference to the basal ganglia, what is the function of the direct pathway?

Answer 21

– facilitate a specific movement programme • Neurons from the striatum that project to the GPi directly.

Question 22

with reference to the basal ganglia, what is the function of the indirect pathway?

Answer 22

– inhibit a specific movement programme, to allow direct pathway’s programme. • Neurons from the striatum that project to GPe. From the GPe, neurons project strongly to the subthalamic nucleus which later projects back to GPi

Question 23

with reference to the basal ganglia, would flexing your arm be a result of the direct or indirect pathway?

Answer 23

direct

Question 24

with reference to the basal ganglia, would relaxing the extensors in your hand be a result of the direct or indirect pathway?

Answer 24

indirect

Question 25

with reference to the basal ganglia, which pathway leads to excitation of the cortex from the thalamus?

Answer 25

direct pathway

Question 26

with reference to the basal ganglia, which pathway leads to inhibition of the cortex from the thalamus?

Answer 26

indirect pathway

Question 27

what is the Role of the substantia nigra pars compacta?

Answer 27

• release dopamine - initiates movement - excites direct pathway (inhibitors indirect pathway)

Question 28

what would the consequences be if the if the substantia nigra is diminished/lesioned?

Answer 28

Can not INITIATE MOVEMENT

Question 29

which receptor does dopamine bind to to have an inhibitory effect?

Answer 29

D2 receptor

Question 30

which receptor does dopamine bind to to have an excitatory effect?

Answer 30

D1 receptor

Question 31

degenerative changes that affect basal ganglia circuitry leads to what kind of disorders?

Answer 31

hyperkinetic disorders – unwanted movements occur - Hemiballismus - Chorea (Huntington’s disease)

Question 32

Degeneration of inhibitory fibres form striatum to globus pallidus results in which disorder?

Answer 32

Chorea (Huntington’s disease)

Question 33

Degeneration of subthalamic nucleus (excitatory to globus pallidus) results in which disorder?

Answer 33

Hemiballismus

Question 34

describe the afferent connections of the basal ganglia

Answer 34

Question 35

describe the efferent connections of the basal ganglia

Answer 35

Question 36

describe the indirect/direct connections of the basal ganglia

Answer 36