Basal Ganglia 32

Question 0

Other functions of basal ganglia (not including primary function) - 5

Answer 0

Procedural learning
Routine behaviours or habits
Eye movements
Cognition and emotion
Action selection from several possible choices

Question 1

Primary function of the basal ganglia?

Answer 1

Likely to control and regulate activities of the motor and Premotor cortical areas so that the voluntary movements can be performed smoothly
(Acts as gating tool - selects movement for us)

Question 2

Def. Ganglia (with respect to basal ganglia)

Answer 2

Collection of cell bodies

- generally refers to outside of the CNS but with basal ganglia is primarily found within CNS

Question 3

Basal ganglia is made up of multiple nuclei deep within the cortex. What are they?

Answer 3

Striatum (caudate nucleus and putamen)
Globus Pallidus (external and internal pallidum)
Subthalamic nucleus
Substantia nigra (pars reticula, compacta)

Listed from top down

Question 4

What two structures make up the Striatum?

Answer 4

Caudate nucleus and putamen

- similar function, separated by the internal capsule

Question 5

Features of the Globus Pallidus? (Internal and external pallidum)

Answer 5

• the breaks on motor movements

- always firing, even at rest – inhibits thalamus

Question 6

Feature of the Subthalamic nucleus ?

Answer 6

Important nucleus in the indirect pathway

Question 7

Substantia nigra 2 parts and importance

Answer 7

Pars reticulata - major output before brain
Pars compacta - releases dopamine

-line runs down middle of the Substantia nigra separating the two parts

Question 8

The main recipient of afferent input at the basal ganglia?

Answer 8

The striatum

Question 9

The striatum receive afferent input from 3 places?

Answer 9

Cerebral cortex - excitatory
Thalamus - excitatory
Substantia nigra - both excitatory and inhibitory depending on the receptor

Question 10

The major output structures (efferent connections) of the basal ganglia are? Where does the output go and what affect does it have?

Answer 10

Globus Pallidus (internus) 
Substantia nigra (pars reticulata)

Project primarily to the thalamus
Both inhibitory

Question 11

3 types of internal connections between nuclei of the basal ganglia?

Answer 11

Direct
Indirect
Nigrostriatal

Question 12

What is the importance of multiple pathways of the interconnections between nuclei of the basal ganglia?

Answer 12

To coordinate agonist and antagonist muscles

Question 13

Where do the direct and indirect pathways of the basal ganglia begin?

Answer 13

Both begin at the striatum (caudate & putamen)

Question 14

Features of the direct pathway of the basal ganglia?

Answer 14

• 2 synapses: double inhibitory ( double negative = positive)
• overall excitatory
• excites the M1
• facilitates movement

Question 15

Features of the indirect pathway of the basal ganglia?

Answer 15

3 synapses: triple inhibitory
Overall inhibitory
Inhibits the M1
Inhibits movement

Question 16

Purpose of the Nigrostriatal pathway in the basal ganglia?

Answer 16

Modulates the directs and indirect pathways

Dopaminergic projections from the Substantia nigra (pars compacta) releases dopamine to the striatum

• direct pathway has d1 dopamine receptors (depolarize)
• indirect pathways has d2 receptors (hyper polarize)

Question 17

What does the Nigrostriatal pathway ultimately do?

Answer 17

Has dual affect

• excites the direct pathway
• inhibits the indirect pathway

End result EXCITATORY

Question 18

Diseases that can result from impaired function of the basal ganglia?

Answer 18

Parkinson’s

Huntington’s disease

Question 19

Basal ganglia does NOT initiate movement on its own, but does what instead?

Answer 19

Acts to “gate/select the correct execution” of automatic programs in the motor output hierarchy

Question 20

Treatments for Parkinson’s disease? (3)

Answer 20

• L-Dopa: converted into dopamine after injected, restores normal levels. Effects wear off over time
• Pallidotomy: destroys Globus Pallidus (inhibitor)
• Deep brain stimulation: pacemaker implanted under skin, electrical impulses to brain

Question 21

What is Parkinson’s disease? Cause? Symptoms?

Answer 21

Neuro degenerative disease
Generally genetic for early onset but not all have genetic origin (idiopathic)
Due to loss of Dopaminergenic neurons in Substantia nigra
- rigidity, resting tremor, poor movement initiation, stooped posture, mvt slowness

Question 22

What is Huntington’s disease? Cause? Symptoms?

Answer 22

Progressive brain disorder caused by “defective gene” (GENETIC)

• selective loss of neurons in “indirect pathway” leading to “too much” excitation (high dopamine levels)
• choreiform movements (brief involuntary non specific and non patterned)
• involuntary continuous movements, decline in thinking/reasoning skills

Question 23

Is there a cure for huntingtons disease?

Answer 23

No

• no way to delay onset or slow down disease
• treatments aim to relieve symptoms (chorea and psychiatric problems)