Cerebellar Motor Systems

Question 1

What is the center of the cerebellar cortex called?

Answer 1

the vermis

Question 2

What are the cereballar nuclei, from lateral to medial?

Answer 2

Don’t Eat Green Frogs

Dendate nucleus

Emboliform nucleus

Globose nucleus

Fastigial nucleus

Question 3

What are the three distinct cortical layers of the cerebellum?

Answer 3

molecule layer

pukinje cell layer

granular layer

Question 4

What are the five intrinsic neurons in the cerebellar cortex?

Answer 4

1. purkinje cells
2. granule cells

then inhibitory interneurons:

3. stellate cells
4. basket cells
5. Golgi cells

Question 5

Are the purkinje cells output or input cells?

Inhibitory or excitatory?

What NT?

Answer 5

They are the ONLY output cell from the cerebellum

they are inhibitory to the cerebellar/vestibular nuclei

release GABA

Question 6

How do the purkinje cells get their input?

Answer 6

they receive input from the parallel fiber and climbing fiber systems

Question 7

What cells form the parallel fiber system?

Answer 7

the granule cells

Question 8

Are the grnaule cells excitatory or inhibitory? What NT?

Answer 8

excitatory - glutamate

Question 9

What NT is used by the three groups of inhibitory interneurons?

Answer 9

GABA

Question 10

What excites the inhibitory interneurons?

Answer 10

the parallel fiber system

Question 11

Mossy fiber afferents from multiple areas of the spinal cord and brainstem will synapse on what cells?

Answer 11

the granule cells

Question 12

What kind of action potentials will the mossy fibers ultimately cause in the purkinje cells (via the granular cells)?

Answer 12

simple spikes

they are high frequency discharges that can be modulated up or down to encode temporal and intensity information

Question 13

Where do the climbing fiber afferents come from?

Answer 13

they ONLY come from the inferior olivary complex

Question 14

What cells do the climbing fibers synapse on?

Answer 14

they are monosynaptic to the purkinje cells

Question 15

What kind of action potential will the climbing fibers cause in the pukinje cells? What does this encode?

Answer 15

complex spikes

they are low frequency discharges, only 1 per second

they encode a “teaching signal” to modulate synaptic plasticity

Question 16

Is the cerebellar cortex ipsilaterally, contralaterally or bilaterally organized?

Answer 16

ipsilaterally! It’s weird!

Question 17

The vestibulocerebellum includes what 2 areas of the cerebellum?

Answer 17

the vermis and flocculonodular lobe

Question 18

What function does the vestibulocerebellum deal with?

Answer 18

balance and eye movements

Question 19

Where does the vestibulocerebellum get it’s input from? THrough what kinds of fibers?

Answer 19

from the semicircular canals, otoliths, and visual information from the parietal/occipital to pontine nuclei

via mossy fibers

Question 20

Where will the vestibulocerebellum send its efferent output?

Answer 20

1. vestibular and fastigial nucleu

(so medial vestibulospinal tract and lateral vestibulospinal tract)

2. Gaze centers for eye movement control

Question 21

Dirsorders of the vestibulocerebellar system will result in what symptoms?

Answer 21

1. disturbances of equilibrium (they will fall toward the side of the lesion)
2. nystagmus
3. loss of smooth pursuit eye movements

Question 22

What part of the cerebellum is involved in the spinocerebellum system?

Answer 22

the intermediate zones of the cerebellum

Question 23

Where does the spinocerebellum system get its input from?

Answer 23

1. vestibular inputs
2. spinocerebellar tracts (dorsal and ventral)
3. face somatosensory and proprioceptive inputs

Question 24

Where in the spinal cord do the dorsal spinocerebellar tract and ventral spinocerebellar tract originate?

Answer 24

in the lumbar and thoracic cord

Question 25

What info does the dorsal SCT provide? The ventral SCT?

Answer 25

dorsal = peripheral feedback from cutaneous and proprioceptive receptors

ventral = info on the state of the spinal circuitry

Question 26

To what deep cerebellar nuclei does the intermediate zone project the spinocerebellar info?

Answer 26

the emboliform and the globose nuclei

Question 27

The globose and emboliform nuclei then project to what two areas?

Answer 27

the red nucleus for the rubrospinal tract

the ventral lateral thalamus and motor cortex for the corticospinal tract

Question 28

Disorders of the spinocerebellar system will cause what symptoms?

Answer 28

1. gait disturbances (ataxia if vermis is involved0
2. action tremor
3. limb dysmetria
4. disorders of timing
5. decomposition of movements
6. hypotonia!!!! One of the only central lesions that can cause hypotonia instead of hypertonia!!!!!

Question 29

What region of the cerebellum is involved in the cerebrocerebellum system?

Answer 29

the lateral zones

Question 30

To what deep derebellar nuclei does the cerebrocerebellar system project to?

Answer 30

the dentate

Question 31

Through the dentate nucleus, where does the cerebrocerebellar system project to?

Answer 31

1. ventral lateral nucleus of the thalamus and then to motor cortex (corticospinal tract(
2. prefrontal areas
3. red nucleus –> rubrospinal tract

Question 32

What will disorder of the cerebrocerebellar system cause?

Answer 32

ataxia of the FINEST movements - like hand shaping and writing

subtle cognitive deficits (remember that it projects to the prefrontal cortex)

Question 33

The climbing fibers that arise from the inferior olive come form the ____ side.

Answer 33

contralateral side

Question 34

THe climbing fibers come up ____ to the paralell fibers

Answer 34

orthogonal

Question 35

In general, what does the cerebellum do?

Answer 35

produces smooth, coordinate movements and controls movement timing

also involved in motor learning

predicts the consequences of a movement

Question 36

What is hypothesized to be the neural substrate for motor learning?

Answer 36

long term DEPRESSION

Question 37

In long term depression, what synapse is producing the change and what synapse is actually being modified?

Answer 37

the climbing fibers (with complex spikes) are doing the “teaching” and the parallel fiber/purkinje cell synapse is being modified