Basal Ganglia

Question 1

The basal ganglia is important _______ and __________ voluntary motor functions.

Answer 1

initiating and stopping

Question 2

What are two major disorders caused by diseases of the basal ganglia? What are examples of each?

Answer 2

Hypokinetic Disorders (eg., Parkinson’s disease)

• bradykinesia (akinesia)
• rigidity

Hyperkinetic Disorders (eg., Huntington’s chorea)

• dyskinesia (dystonia)
• hypotonia

Question 3

When the cholinergic system within the basal ganglia have too much relative to dopamine, you lose dopamine in the basal ganglia. Losing dopamine means the cholinergic system has too much relative activity. This is represented in a ___________disorder

Answer 3

hypokinetic

Question 4

If the dopaminergic system is overly active compared to the cholinergic system. This is represented in a _________ disorder

Answer 4

hyperkinetic

Question 5

Drugs that block the _________ system were a major way to treat Parkinson’s disease

Answer 5

cholinergic

Question 6

Basal ganglia is part of the deep nuclei of the cerebral cortex. It is embedded in the __________ (white/gray) matter

Answer 6

white

Question 7

_________ +__________= striatum

Answer 7

Caudate; putamen

Question 8

Label

Answer 8

Question 9

Label

Answer 9

Question 10

What are the two parts of the substantia nigra? Which neurotransmitters are located in each part?

Answer 10

Sunstantia nigra compacta- Dopamine

Substantia nigra reticulata- GABA

Question 11

Crus cerebri is the massive fiber tract going form the cortex to the ________ and __________.

Answer 11

pons and spinal cord

Question 12

With a ___________ stain you can see the two parts of the substantia nigra

Answer 12

Nissl

Question 13

Label

Answer 13

Question 14

The inputs and outputs of the of the basal ganlia go through different nuclei. What are they?

Answer 14

Inputs

• Caudate
• Putamen

Outputs

• Substantia nigra
• Globus pallidas, internal segment

Question 15

What three structures does the striatum receive input from?

Answer 15

• Essentially all areas o the cortex
  
  • Glutaminergic
  • Excitatory
• Substantia nigra
  
  • Dopaminergic
• Thalamus, interlaminar nuclei

Question 16

The putamen and the caudate both make up the striatum but they receive inputs from different areas. How do they differ?

Answer 16

Putamen

• Motor cortex
• Premotor cortex
• Somatosensory cortex

Caudate

• Frontal eye fields
• Associational cortex
  
  • Between the motor and sensory areas

Question 17

Medium spiny neurons make up 90% of _________cells. Whata re some characteristics of these neurons?

Answer 17

striatal

Medium spiny neurons

• GABA-nergic (inhibitory)
• projection cells
• low spontaneous activity

*Needs input

Question 18

What to structures receive striatum output?

Answer 18

• Internal segment of the globus pallidus
• Pars reticulata of the substantia nigra

Question 19

Like the striatum, the internal capsule (IC) divides the output of the basal ganglia into 2 nuclei:

Answer 19

Like the striatum, the internal capsule (IC) divides the output of the basal ganglia into 2 nuclei:

Question 20

Large ________neurons make up the globus pallidus and substantia nigra, pars reticularis. What are the characteristics of these neurons? What is the significance of this?

Answer 20

aspiny

Characteristics

1. have a relatively high rate of spontaneous activity
2. are GABA-nergic (ie., inhibitory)
3. are projection neurons

*This is why the thalamus is tonically inhibitted

Question 21

Remember globus pallidus projects to ____________neurons, because of the high level of activity there is a lot of GABA release, leading to tonic inhibition of thalamic neuron. This quiets the thalamic neuron

Answer 21

thalamocortical

Question 22

A pulse of corticostriatal input results in:

Answer 22

1) striatal excitation
2) pallidal inhibition
3) thalamic disinhibition

Question 23

In Huntington’s disease, the ________degenerates as evident by enlargement of the __________.

Answer 23

striatum; lateral ventricle

NOTE: The caudate nucleus is extremely vulnerable

Question 24

Chorea

Answer 24

Chorea describes individual, brief, purposeless, nonrepetitive jerks of muscles

•Rhythmic, slow moving

*More centered to the caudate

Question 25

Athetosis

Answer 25

Slow, writhing, continuous, wormlike movements of the distal extremities. Difficult to differentiate from chorea

Question 26

Athetosis is thought to be involved in degeneration of the \_\_\_\_\_\_\_\_\_\_\_.

Answer 26

Putamen

Question 27

Hemiballism usually occurs when?

Answer 27

After a cerebral vascular incident \***occurs on the opposite side of the lesion**

Question 28

Vascular lesions of the ___________ are thought to produce hemiballism

Answer 28

subthalamus

Question 29

Which pathway is the subthalamus apart of?

Answer 29

The indirect pathway

Question 30

Globus pallidus externis synapse in the \_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 30

subthalamus \*Globus pallidus has large aspiny neurons that are GABAnergic, which leads to inhibition of the subthalamus

Question 31

Subthalamus is excitatory and projects to the ___________ and \_\_\_\_\_\_\_\_\_\_.

Answer 31

globus pallidus internis and substantia nigra

Question 32

Rest tremor

Answer 32

Tremor ameliorated with purposeful movement

Question 34

Dopamine from the substantia nigra pars ___________ modulates the neural activity in the striatum.

Answer 34

compacta (SNc)

Question 35

The dopaminergic input into the ‘direct’ pathway is mediated by ________ receptors and is \_\_\_\_\_\_\_\_\_\_\_. The dopaminergic input into the ‘indirect’ pathway is mediated by ______ receptors and is \_\_\_\_\_\_\_\_\_\_\_.

Answer 35

D1; excitatory D2; inhibitory

Question 36

The presence of D2 agonist will result in \_\_\_\_\_\_\_\_\_\_

Answer 36

Hyperkinesia

Question 37

The presence of D1 antagonist will result in \_\_\_\_\_\_\_\_\_\_

Answer 37

Hypokinesia

Question 38

What are the three major symptoms of parkinson's disease?

Answer 38

* Resting tremor * Rigidity * Bradykinesia, which progresses to akinesia

Question 39

What are the 4 basic strategies for treating Parkinson's disease?

Answer 39

* **L-dopa** (replacement) therapy * **stereotaxic lesions** of the internal segment of the globus pallidus (GPi, pallidotomy) * **deep brain stimulation** of GPi or subthalamus (in clinical trial stage) * **brain transplant** (no comment)

Question 40

Does L-Dopa stop the disease process?

Answer 40

**No!** **\***It only works as long as you still have neurons

Question 41

Using stereotaxic coordinates, an electrode can be position in the \_\_\_\_\_\_\_\_\_\_which then can be electrolytically lesioned.

Answer 41

globus pallidus