L2.3 Motor Control by Basal Ganglia and Cerebellum

Question 1

List the constituent parts of the basal ganglia

Answer 1

Question 2

Answer 2

Nucleus accumbens

Question 3

What are the general roles of the basal ganglia?

Answer 3

1. Provide a feedback mechanism to the cerebral cortex for initiation and control of motor responses
2. Acts as a gate that enables the execution of automatic programs in the hierarchy
3. Switches activation of one part of the cortex on and another off
4. Helps program automatic response sequences
5. Reduces muscle tone

Question 4

What specific part of the basal ganglia inhibits output from the thalamus?

Answer 4

The globus pallidus internus

Question 5

What is disinhibition?

Answer 5

Inhibiting inhibition

Question 6

Answer 6

Question 7

When the striate is mentioned, what does it generally mean?

Answer 7

Caudate nucleus and putamen combined

Question 8

The direct pathway through the basal ganglia will ____ movement/excitatory output from the thalamus

Answer 8

The direct pathway through the basal ganglia will decrease movement/excitatory output from the thalamus

Question 9

The indirect pathway through the basal ganglia will ____ movement/excitatory output from the thalamus

Answer 9

The indirect pathway through the basal ganglia will increase movement/excitatory output from the thalamus

Question 10

In a reasonably basic manner, describe how the direct pathway of the basal ganglia can promote excitatory movement output of the thalamus (4)

Answer 10

1. The cortex decides that a certain movement that is being stimulated by the thalamus needs to be promoted, so excitatory input is sent to the striatum
2. Upon being excited by this input, the striatum (caudate nucleus or putamen) sends inhibitory output to the globus pallidus internus and the reticular part of the substantia nigra
3. Normally, the globus pallidus internus inhibits the thalamus, however, upon receiving the inhibitory input, the globus pallidus internus inhibition of the thalamus is inhibited (disinhibition)
4. The thalamus can now send increased amounts of excitatory output to the cortex

Question 11

In a reasonably basic manner, describe how the indirect pathway of the basal ganglia can inhibit excitatory movement output of the thalamus (4)

Warning: dis complicated

Answer 11

1. Excitatory cortical output is sent into the putamen
2. This causes the putamen to send inhibitory output to the globus pallidus externus
3. The globus pallidus externus normally sends inhibitory signals to the subthalamus, so its inhibition triggers disinhibition of the subthalamus
4. The subthalamus normally promotes the activity of the globus pallidus internus, so the inhibition of the globus pallidus externus disinhibits the subthalamus, which in turn will increase the subthalamus’s promotion of the activity of the glubs pallidus internus
5. Globus pallidus internus inhibits the thalamus, so increased GPI activity thanks to the subthalamus stimulation will increase inhibition of the thalamus and thus decreases the thalamus’s excitatory output (therefore reducing movement)

Question 12

What would the loss of subthalamic projections to the globus pallidus internus ultimately do?

Answer 12

The loss of subthalamic projections to the globus pallidus internus would decrease excitation of the GPI.

The GPI inhibits the thalamus, so a decrease in the excitation of the GPI would disinhibit the thalamus, resulting in increased thalamus activation of the cortex and increase involuntary movement

Question 13

How does dopamine increase movement with regard to the basal ganglia?

Answer with reference to the direct and indirect pathways

Answer 13

Question 14

What would happen with the direct and indirect basal ganglia pathway if there was a decrease in the release of dopamine like happens in the case of Parkinson’s Disease

Answer 14

Question 15

List whether the superior, middle, and inferior cerebellum peduncles have mainly afferent or efferent fibres in them

Answer 15

Superior: mainly efferent (sending the message up high to the cortex)

Middle (Largest): Receiving information, so afferent

Inferior: Receiving information, so afferent

Question 16

Answer 16

Question 17

What are the folia of the cerebellum?

Answer 17

The term used instead of gyri

Tight, mini convolutions.

Question 18

What are the names of the nuclei residing in the white matter deep to the cortex in the cerebellum of the brain?

Answer 18

Question 19

The dentate nuclei relate to _______ output

Answer 19

cerebrocerebellum output

Question 20

Which cerebellar nuclei relates to cerebrocerebellar output?

Answer 20

The dentate nuclei

Question 21

Which cerebellar nuclei relates to the lateral aspect of spinocerebellum input?

Answer 21

Interposed Nuclei

Question 22

Which cerebellar nuclei pertains to the vermis?

Answer 22

Fastigial nuclei

Question 23

The cerebellar interposed nuclei relate to?

Answer 23

The lateral aspect of spinocerebellum input

Question 24

The cerebellar fastigial nuclei pertain to?

Answer 24

the vermis

Question 25

Answer 25

Flocculonodular lobe

Question 26

Answer 26

Question 27

What are the functions of the cerebellum and where is its output directed?

Answer 27

1. Error corrections * Integrates executive commands with sensory feedback for moment to moment adjustments 2. Facilitates learning when errors are numerous - "whoah, that was shit, need to make sure we learn how to do better next time" 3. Output directed to UMN not LMN - aware of output and therefore can learn from it 4. An organ of agility * Can coordinate multijointed movements, often in a precise sequence 5. Cognitive processes of Problem solving (e.g. problem-solving that requires coordination of multi located sequential nuclei) - ***Controls who goes next***

Question 28

Answer 28

Question 29

Answer 29

Question 30

Summary of cerebellar functions (not a test card, but a prompt card)

Answer 30

Question 31

List 4 cerebellar dysfunctions

Answer 31

Question 32

What is the lenticular nucleus comprised of?

Answer 32

Part of the basal ganglia Includes: - Putamen Globus Pallidus internus Globus Pallidus externus

Question 33

What is the neostria pathway?

Answer 33

The pathway between the cortex and the putamen

Question 34

What is the nigrostriatal pathway?

Answer 34

The pathway that connects the Substantia Nigra pars compacta (SNc) to the putamen and caudate nucleus

Question 35

What is the corticostriatal pathway?

Answer 35

Contains neurons that project from nearly all regions of the cerebral cortex to the striatum. The corticostriatal pathway is the primary input pathway for the basal ganglia.

Question 36

Answer 36

Question 37

Answer 37