cerebellum connections

Question 1

What are the most numerous form of input to the cerebellum?

Answer 1

mossy fibers

Question 2

Are mossy fibers excitatory or inhibitory?

Answer 2

excitatory (glutaminergic) synapses with glutaminergic mediated EPSPs

Question 3

Where do the EPSPs of mossy fibers end?

Answer 3

primarily on granule cells ( whose axons ascend to form parallel fibers up into the molecular layer)

Question 4

the parallel fibers of the molecular layer synapse with what?

Answer 4

glutaminergic excitatory endings on the dendrites of Purkinje cells

Question 5

when the parallel fibers excite purkinje cells, what happens?

Answer 5

each produces a small EPSP which summates to activate the purkinje cells

Question 6

What do most of the mossy fibers enter through?

Answer 6

inferior and middle cerebellar peduncles (some superior)

Question 7

Where do mossy fibers originate from/

Answer 7

vestibular primary afferent fibers via inferior peduncle
vestibular nuclei via inferior peduncle
spinal cord (spinocerebellar tracts) via inferior cerebellar peduncle (ventral SCT through superior peduncle)
cerebral cortex via pontine nuclei and pontocerebellar fibers (middle peduncle)

Question 8

mossy fibers end on?

Answer 8

Golgi cells- inhibitory interneurons of the granule cell layer

Question 9

Where do climbing fibers originate from?

Answer 9

contralateral inferior olivary nucleus

Question 10

Climbing fibers end on purkinje cells with what type of synapse

Answer 10

excitatory ASPARTATE synapses

Question 11

what do climbing fibers produce?

Answer 11

large EPSPs which produce bursts of purkinje cell action potential activity when activated

Question 12

How many climbing fibers does each purkinje cell receive?

Answer 12

just a single climbing fiber

Question 13

how many purkinje cells do climbing fibers innervate?

Answer 13

only 1-3

Question 14

Compared to mossy fibers, climbing fibers are?

Answer 14

very specific with input unlike the widespread generalized input of the mossy fiber/granule cell parallel fiber system

Question 15

What type of signals do climbing fibers provide?

Answer 15

feed forward signals from the cerebral cortex to the cerebellum vis cortico-olivary and olivocerebellar fibers

Question 16

What type of signals do mossy fibers provide?

Answer 16

feedback signals from spinal, vestibular, and other inputs

Question 17

What are Golgi cells (inhibitory interneurons of the granule cell layer) innervated by?

Answer 17

both mossy and parallel fibers

Question 18

What action do Golgi cells have?

Answer 18

inhibitory action (GABA) on granule cell dendrites

Question 19

What do basket and stellate cells both produce?

Answer 19

GABAminergic inhibitory action on purkinje cells

Question 20

basket and stellate cells produce a prolonged inhibition that has been related to what?

Answer 20

associative learning in the cerebellum

Question 21

What is outflow of the cerebellar cortex from?

Answer 21

purkinje neurons and GABAminergic IPSPs (inhibitory potentials)

Question 22

where do purkinje neurons project?

Answer 22

deep cerebellar nuclei

vestibular nuclei

Question 23

outputs from the deep cerebellar nuclei are modulated by?

Answer 23

mossy and climbing fibers collaterals to deep cerebellar nuclei

Question 24

mossy and climbing fibers create an excitatory drive which is then sculpted by what?

Answer 24

inhibitory influence of the purkinje neurons