cerebellum connections Flashcards
What are the most numerous form of input to the cerebellum?
mossy fibers
Are mossy fibers excitatory or inhibitory?
excitatory (glutaminergic) synapses with glutaminergic mediated EPSPs
Where do the EPSPs of mossy fibers end?
primarily on granule cells ( whose axons ascend to form parallel fibers up into the molecular layer)
the parallel fibers of the molecular layer synapse with what?
glutaminergic excitatory endings on the dendrites of Purkinje cells
when the parallel fibers excite purkinje cells, what happens?
each produces a small EPSP which summates to activate the purkinje cells
What do most of the mossy fibers enter through?
inferior and middle cerebellar peduncles (some superior)
Where do mossy fibers originate from/
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)
mossy fibers end on?
Golgi cells- inhibitory interneurons of the granule cell layer
Where do climbing fibers originate from?
contralateral inferior olivary nucleus
Climbing fibers end on purkinje cells with what type of synapse
excitatory ASPARTATE synapses
what do climbing fibers produce?
large EPSPs which produce bursts of purkinje cell action potential activity when activated
How many climbing fibers does each purkinje cell receive?
just a single climbing fiber
how many purkinje cells do climbing fibers innervate?
only 1-3
Compared to mossy fibers, climbing fibers are?
very specific with input unlike the widespread generalized input of the mossy fiber/granule cell parallel fiber system
What type of signals do climbing fibers provide?
feed forward signals from the cerebral cortex to the cerebellum vis cortico-olivary and olivocerebellar fibers
What type of signals do mossy fibers provide?
feedback signals from spinal, vestibular, and other inputs
What are Golgi cells (inhibitory interneurons of the granule cell layer) innervated by?
both mossy and parallel fibers
What action do Golgi cells have?
inhibitory action (GABA) on granule cell dendrites
What do basket and stellate cells both produce?
GABAminergic inhibitory action on purkinje cells
basket and stellate cells produce a prolonged inhibition that has been related to what?
associative learning in the cerebellum
What is outflow of the cerebellar cortex from?
purkinje neurons and GABAminergic IPSPs (inhibitory potentials)
where do purkinje neurons project?
deep cerebellar nuclei
vestibular nuclei
outputs from the deep cerebellar nuclei are modulated by?
mossy and climbing fibers collaterals to deep cerebellar nuclei
mossy and climbing fibers create an excitatory drive which is then sculpted by what?
inhibitory influence of the purkinje neurons
