Ebner -- Cerebellum Flashcards
Cerebellar nuclei
Purkinje cells are one of the five intrinsic neruons in cerebellar cortex. What are their characteristics?
Only output neuron
inhibitory (GABA) to cerebellar nuclei (DEGF) and vestibular nucleus.
Receive input from parallel fibers (granule cells) and climbing fibers – both are excitatory (glutamate)
The granule cells of the cerebellum serve what function?
major input to purkinje cells via parallel fibers
excitatory (glutamate)
Basic cerebellar circuitry:
- Mossy fibers –>
- climbing fibers (inferior olivary nucleus) –>
purkinje cells –>
cerebellar nuclei –>
–> granule cells –> purkinje cells (excitatory; glutamate)
–> purkinje cells (glutamate) (contralateral)
–> cerebellar nuclei and vestibular nucleus
–> many targets in CNS
What produces simple spikes in purkinje cells?
Mossy fiber afferents (via excitatory glutamate)
high frequency discharge encoding temporal and intensity information
What produces a complex spike in purkinje cells?
climbing fiber afferents (excitatory via glutamate)
slow (1 spk/sec) but powerful excitation
“teaching signal”
Name the three cerebellar functional divisions…
- Vestibulocerebellum
- Spinocerebellum
- Cerebrocerebellum
Vestibulocerebellum input and output
- input: mossy fibers from semicircular canals, otoliths, visual system
- output: vestibular and fastigial nuclei, medial (controls trunk/neck) and lateral (controls limb) vestibulospinal tract, gaze centers (eye movements)
If you have a right vestibulocerebellum lesion, what would you find on Rhomberg test?
Patient falls to same side as lesion… so to the right
spinocerebellum is located where?
in the intermediate zone just lateral to the vermis
Spinocerebellum receives input from where?
3 areas: 1. vestibular/cochlear, 2. spinocerebellar tracts (DSCT and VSCT; both double cross!), 3. face somatosensory and proprioceptive.
Lesions of the spinocerebellum result in what symptoms?
gait ataxia
action tremor/voluntary tremor
hypotonia
Name the inputs and outputs of the cerebrocerebellum…
Most lateral zone of the cerebellum
Inputs: pontine nuclei (sensory, primary motor, premotor and parietal cortices)
Outputs: through dentate nuclei to VL nucleus of thalamus, then to primary motor and premotor cortex. Also, prefrontal areas and red nucleus.
Disorders of the cerebrocerebellum manifest how?
ataxia of the finest movements (hand shaping/writing)
(lesion of the dentate nucleus has similar effects)
The climbing fiber system originates where?
contralateral inferior olive
(goes to purkinje cells)
