Term
| What is the primary function of the cerebellum? |
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Definition
| To produce coordination of movements |
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Term
| Will lesions in the cerebeullum produce sensory defecits or muscle weekness? |
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Definition
| No, they produce disturbances in coordination of movement, muscle tone, and/or posture |
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Term
| What are the three lobes of the cerebellum? |
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Definition
1. Anterior lobe, separated by primary fissure from
2. Posterior lobe, separated by posterolateral fissure from
3. Flocculonodular lobe |
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Term
| What are the 3 major mediolateral regions of the cerebellum? |
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Definition
1. Vestibulocerebellum (flocculonodular lobe and adjacent
vermis)
2. Spinocerebellum (most of vermis and paravermal zone)
3. Cerebrocerebellum (hemispheric or lateral zone) |
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Term
| What are the three cerebellar deep nuclei? |
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Definition
1. Fastigial nucleus
2. Interposed nuclei
3. Dentate nucleus |
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Term
| What are the functions of the vestibulocerebellum? |
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Definition
1. Input/output of vestibular structures
2. Relations of body and head in space, equilibrium, balance
3. Posture/muscle tone via brainstem medial pathways |
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Term
| What are the functions of the spinocerebellum? |
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Definition
Receives input from and sends output to muscles; influences axial and girdle muscles, and proximal limb muscles
2. Controls ongoing movements |
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Term
| What are the functions of the cerebrocerebellum? |
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Definition
1. Input from and output to cerebral cortex
2. Mainly involved in planning, initiation, and timing of movements,
particularly skilled movements. Involves hand and forearm mainly. |
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Term
| Would a cerebellar lesion affect contralateral or ipsilateral muscles? |
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Definition
| Cerebellar lesions affect muscles on ipsilateral side, except for midline lesions which can affect axial muscles on both sides. |
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Term
| Define asynergia/dyssynergia |
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Definition
|
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Term
|
Definition
| Inaccurate range and direction of movement. Movements overshoot (hypermetria) (mainly) or undershoot (hypometria) their target. |
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Term
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Definition
| Wide stance and unsteady walking in gait, if regions of cerebellum regulating lower limbs is affected. Resembles drunkenness. A truncal ataxia (unsteady lurching gait) is due to vestibulocerebellar damage. |
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Term
| Define dysdiadochokinesia |
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Definition
Cannot perform rapid alternating movements
(such as the ASL sign for "cook" :) ) |
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Term
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Definition
| Oscillations as limb moves toward target |
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Term
|
Definition
| Lose facilitation from deep nuclei. |
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Term
|
Definition
| Hallucination of movement |
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Term
|
Definition
| Scanning speech; mechanical aspects of speech are abnormal |
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Term
| What are the "classic" basal ganglia |
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Definition
| Caudate nucleus, putamen, and globus pallidus |
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Term
| What are the functions of basal ganglia |
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Definition
A. Initiation of movement
B. Permissive effect on movement
C. Control gross movements
D. Adjust body position appropriately for a given task; adjust motor set |
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Term
| Describe the direct pathway in the basal ganglia |
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Definition
1. Putamen → Globus pallidus (medial) → Thalamus
2. Disinhibits thalamus, thereby increasing thalamocortical activity
(red arrow=inhibits) |
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Term
| Describe the indirect pathway in the basal ganglia |
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Definition
1. Putamen → Globus pallidus (lateral) → Subthalamic nucleus → Globus pallidus (medial) → Thalamus
2. Inhibits thalamus, thereby decreasing thalamocortical activity
(red arrow=inhibits, green=excites) |
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Term
| Define hypokinetic disorder |
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Definition
Reduced movements which are characterized as akinesia (problem with initiation of movement) and bradykinesia (reduction in speed and amplitude of movements). The hypokinetic movements are superimposed on muscular rigidity.
Activity in the thalamocortical projection is reduced. |
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Term
| What causes Parkinson's disease? |
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Definition
| A loss of dopaminergic neurons in the nigrostriatal pathway. Cell bodies in the substantia nigra die. As a result, their axons projecting to the neostriatum also die, which produces a severe reduction in dopamine content in the neostriatum. |
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Term
| What are symptoms of Parkinson's disease? |
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Definition
1. Resting tremor: Alternating contractions of antagonistic muscles, at a frequency of 3-6 Hz.
2. Plastic, or lead-pipe, rigidity; cogwheel rigidity
3. Bradykinesia and akinesia |
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Term
| How can Parkinson's disease be treated pharmacologically? |
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Definition
| Since the cause is the loss of dopaminergic neurons, treatment is designed to replace the dopamine; administer L-DOPA. Note that this will only work if there are enough axon terminals still alive in the neostriatum. |
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Term
| Define hyperkinetic disorder |
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Definition
Hyperkinetic disorders produce dyskinesias (increased movements). Movements are rapid and uncontrollable. These uncontrollable movements are superimposed on the desired movements. Dyskinesias are generally superimposed on reduced muscular tone.
Activity in the thalamocortical projection is enhanced |
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Term
| What are examples of hyperkinetic movements? |
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Definition
a. Chorea (dance-like movements)
b. Athetosis
c. Ballism
d. Tics (Tourette's syndrome) |
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Term
| What causes Huntington's disease? |
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Definition
| Death of cell bodies of the output neurons of caudate and putamen: those neurons projecting to globus pallidus. |
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Term
| What are symptoms of Huntington's disease? |
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Definition
1. Chorea
2. Dementia
3. Inherited (dominant), adult onset |
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Term
| How is Huntington's disese treated? |
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Definition
| Dopamine receptor antagonists reduce abnormal movements, and dopamine agonists enhance movements. |
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Term
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Definition
| Death of cell bodies in the subthalamic nucleus. This leads to a reduction of excitatory drive to the medial globus pallidus, which thereby reduces the inhibitory drive on thalamus. Thus, the thalamocortical projection is enhanced; this enhancement seems to explain the increased movements. |
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