Motor Systems: Cerebellum Flashcards Preview

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Flashcards in Motor Systems: Cerebellum Deck (19):
1

What are the deep cerebellar nuclei from lateral to medial? What are their functions?

(Don't Eat Green Frogs)
Dentate, Emboliform, Globose, Fastigial
-Excitatory and lead to activation of neurons in motor control centers

2

What are mossy fibers? What is their purpose? Where do they terminate in the cerebellum?

Mossy fibers are a heterogeneous group of afferents carrying reference input and efference copy. ALL afferent inputs to the cerebellum, except for inputs from the inferior olives (climbing fibers), are mossy fibers.

*Produce simple spikes in Purkinje cells, high frequency discharge

Terminate in:
-Deep cerebellar nuclei (directly excite)
-Cerebellar cortex (excite granule cells that indirectly excite Purkinje cells)

3

Where do mossy fibers primarily form from?

-the periphery via spin and cuneocerebellar tracts
-Motoneurons, motor interneurons, and central pattern generators via spino and cuneocerebellar tracts
-Vestibular info, arriving via the vestibular nerve and nuclei
-Cortex, including motor, premotor, somatosensory, and visual areas, via a synapse in the pontine nuclei

4

What are Purkinje cells?

Only output neuron, inhibitory (GABA) to cerebellar nuclei/vestibular nucleus; receives input from parallel fiber and climbing fibers

5

What are granule cells?

Origin of parallel fiber system, excitatory (glutamate) to Purkinje cells and inhibitory interneurons.

6

What are the three inhibitory interneurons?

Stellate, basket, and Golgi cells. All excited by parallel fibers

7

What are climbing fibers?

-Come solely from contralateral inferior olive.
-Monosynaptic to Purkinje cells, resulting in powerful excitation known as complex spikes
-Low frequency discharge
-May encode teaching signal

8

Where does the vestibulocerebellum (flocculonodular lobe and vermis) project to?

-Vestibular and fastigial nuclei
-Medial vestibulospinal tract (controls trunk/neck muscles)
-Lateral vestibulospinal tract (controls limb muscles)
-Gaze centers (controls eye movements)

9

The following symptoms are due to disorders of what division of the cerebellum?
-Disturbances of equilibrium (fall toward side of lesion)
-Nystagmus
-Loss of smooth pursuit eye movements

Vestibulocerebellum. Lesioning fastigial nucleus has similar effects.

10

Dorsal spinocerebellar tract

Type of info: Reafference
Body parts: Legs and trunk
Arises from: Clarke's nucleus
Enters thru: Restiform body/inferior cerebellar peduncle

11

Ventral spinocerebellar tract

Type of info: Efference copy
Body parts: Legs and trunk
Arises from: Ventral horn
Enters thru: Superior cerebellar peduncle

12

Cuneocerebellar tract

Type of info: Reafference
Body parts: Arms
Arises from: External cuneate nucleus
Enters thru: Restiform body/inferior cerebellar peduncle

13

Rostral spinocerebellar tract

Type of info: Efference copy
Body parts: Arms
Arises from: Ventral horn
Enters thru: Restiform body/inferior cerebellar peduncle

14

The following symptoms are due to a disorder of what area of the cerebellum:
-Disturbances of gait (vermis)
-Hypotonia
-Action tremor
-Limb ataxia/dysmetria
-Disorders of timing (dysdiadochokinesia)
-Decomposition of movements

Spinocerebellum. Lesioning the emboli form and globose nuclei has similar effects.

15

Where does the spinocerebellum project to?

-Vermis projects to fastigial nucleus (reticulospinal tract and vestibulospinal)
-Intermediate zone projects to globose and emboliform nuclei which project to red nucleus (controls rubrospinal tract) and ventral lateral thalamus and the motor cortex (controls corticospinal tract)

16

Where does the cerebrocerebellum (cerebellar hemispheres lateral zones) get input from?

-Pontine nuclei

17

Where does the cerebrocerebellum project to

Via dentate nuclei to VL of thalamus, prefrontal areas, and red nucleus

18

Damage to what area of cerebellum results in the following symptoms:
-Ataxia of finest movements
-Cognitive deficits?

Cerebrocerebellum (lesioning the dentate nucleus has similar effects).

19

How does the cerebellum predict the consequences of a motor action?

By comparing efferent copies (what is supposed to happen) with reafferents (what actually is happening). Learning is used to improve these predictions.