74 - Basal Ganglia Function

Question 1

Akinesia

Answer 1

Complete or partial loss of muscle movement

Difficulty in initiating movement is sometimes called akinesia, sometimes called bradykinesia.

Question 2

Chorea

Answer 2

Dance-like, involuntary, rapid movements. Can be associated with Huntington disease, rheumatic fever, systemic lupus erythematosus, and other conditions

Brief, sudden, random, twitch-like movements of limbs or facial muscles. They resemble fragments of normal voluntary movement.

Question 3

Bradykinesia

Answer 3

Slowness in the execution of movement

Difficulty in initiating movement is sometimes called akinesia, sometimes called bradykinesia.

Question 4

Athetosis

Answer 4

Slow, twisting, writhing movements, with larger amplitude than chorea, commonly involving the hands

Question 5

Hemiballismus

Answer 5

Jerking and twitching movements of one side of the body (involuntary violent flinging or jerking of a limb or limbs in an uncoordinated manner caused by a lesion of the contralateral subthalamus)

Can also be ballismus

Question 6

Dyskinesia

Answer 6

Defect in voluntary movement.

Question 7

Freezing of gait

Answer 7

Freezing of gait (Frozen gait syndrome) can occur in patients with Parkinson’s disease. (This symptom can also be associated with primary progressive frozen gait, a disease with many names.) Parkinson’s Disease patients with this symptom can suddenly be unable to start walking or just stop moving forward while walking. First appears as hesitation in starting to walk or turn. There has been considerable research to develop better rehabilitation treatments. Various sensory cuing methods (auditory, visual) have proved useful.

Question 8

Festinating gait

Answer 8

Abnormal gait, small shuffling steps and the absence of arm swing that normally accompanies walking. As disease progresses the patient tends to walk faster to prevent a fall due to flexed posture which alters their center of gravity. (festinating gait)

A cardinal symptom of Parkinson’s disease

Question 9

What structures comprise the basal ganglia?

Answer 9

1 - Caudate
2 - Putamen
3 - Globus pallidus (internal and external segments - GPi and GPe)
4 - Subthalamic nucleus
5 - Substantia nigra (pars reticulata and pars compacta (the pigmented part))

Question 10

What is an alternate set of terms to describe the basal ganglia?

Answer 10

• Corpus striatum
• Neostriatum
• Paleostriatum

Question 11

Corpus striatum

Answer 11

Neostriatum + paleostriatum

Question 12

Neostriatum

Answer 12

Neostriatum = striatum = putamen + caudate nucleus

Question 13

Paleostriatum

Answer 13

Paleostriatum = pallidum = globus pallidus

Question 14

Which neurotransmitters are important in the nigrostriatal pathway?

Answer 14

SNc projection to striatum (caudate and putamen) releases dopamine

• Several different subtypes of dopamine receptors
• Dopamine can have excitatory or inhibitory effects depending on receptor type.

Question 15

Which neurotransmitters are important in the corticostriate pathway?

Answer 15

Corticostriate projections are excitatory and release glutamate onto medium spiny neurons in striatum

Question 16

Which neurotransmitters are important in pathway from the striatum to the GPe and GPi

Answer 16

Striatum = putamen + caudate
GPe = globus pallidus external
GPe = globus pallidus internal

Medium spiny neurons of striatum are projection neurons to GP. They always release GABA, an inhibitory transmitter.

Question 17

Is GABA usually excitatory or inhibitory?

Answer 17

Inhibitory

Question 18

Is glutamate usually excitatory or inhibitory?

Answer 18

Excitatory

Question 19

What are the cardinal symptoms of Parkinson’s disease?

Answer 19

1 - A rhythmic tremor at rest (4-to-6 Hz tremor)
2 - Increased muscle tone or rigidity - often cogwheel like characteristics
3 - Slowness in the execution of movement (bradykinesia)
4 - Severe slowness of movement can evolve into lack of movement (akinesia). Patient may lack normal facial movements (masked facies). Difficulty in initiating movement is sometimes called akinesia, sometimes called bradykinesia.

Question 20

What are other symptoms seen in Parkinson’s?

Answer 20

• Flexed posture and Postural reflex impairment
• Abnormal gait, small shuffling steps and the absence of arm swing that normally accompanies walking. As disease progresses the patient tends to walk faster to prevent a fall due to flexed posture which alters their center of gravity. (festinating gait)
• Reduced blinking
• Micrographia, small handwriting
• Loss of automaticity of movement: Patient has to exert more voluntary control of previously automatic and well –learned movements.
• Freezing of gait

Question 21

Which neurotransmitter system is most damaged in Parkinson’s disease? Which parts of the basal ganglia does this include?

Answer 21

The degeneration of dopaminergic projection to striatum from substantia nigra is most severely damaged

Question 22

What are the symptoms of Huntington’s disease?

Answer 22

• Chorea - a type of involuntary movement
• Dementia
• Voluntary movements slower than normal

Question 23

Lesions in which location will cause hemiballismus?

Answer 23

Hemiballismus on one side of body is often associated with a lesion in the contralateral subthalamic nucleus.

Question 24

What are the four loops of the basal ganglia?

Answer 24

1 - Body movement loop
2 - Oculomotor loop
3 - Prefrontal loop
4 - Limbic loop

Question 25

Which cortical areas are involved in the body movement loop?

Answer 25

• starts in the motor areas of the cortex: primary motor, premotor and supplementary motor

Question 26

What is the general function of the body movement loop?

Answer 26

• might selectively activate some movements and suppress others
• might be particularly concerned with internally generated movements

Question 27

Which cortical areas are involved in the oculomotor loop

Answer 27

starts in the frontal eye field and supplementary eye field

Question 28

What is the general fucntion of the oculomotor loop?

Answer 28

involved in the control of saccadic eye movements

Question 29

Which cortical areas are involved in the prefrontal loop?

Answer 29

starts in the dorsolateral prefrontal cortex

Question 30

What is the general function of the oculomotor loop?

Answer 30

may regulate the initiation and termination of cognitive processes such as planning, attention and working memory

Question 31

Which cortical areas are involved in the limbic loop?

Answer 31

• starts in the anterior cingulate and orbital frontal cortex
• includes the ventral striatum. Part of the ventral striatum ( the nucleus accumbens) is involved in the addiction to drugs of abuse.

Question 32

What is the general function of the limbic loop?

Answer 32

• may regulate emotional behavior and motivation

- Tourette syndrome is associated with abnormalities in the cortico-striatal-thalamic-cortico pathway /limbic loop