Cerebellum Flashcards
2 functions of cerebellum
- Modulate movement i.e. error dectection
2. Learning new motor skills
What side of the body does the cerebellum control?
Ipsislateral
What happens if you do not have a cerebellum
Clumsy and uncoordinated movement
What is on the superior border?
Occipital lone
What is on the ventral border?
4th ventricle
What are folia?
External transverse folds
What is arbore vitae
tree like appearance
What connects the the 2 hemispheres of the cerebellum?
Vermis
Inferior\Restiform Peduncle - Location
Dorsalateral aspect of the medulla
Inferior\Restiform Peduncle - Input\output
Vestibuli nerve & nuclei
Inferior\Restiform Peduncle - Connected to?
Medulla & spinal cord
Middle\Brachium - Input system
Cortex to pontine nuclei to middle peduncle
Superior Peduncle\ Brachium conjunctivum - Output or Input system?
Output system decussate in the midbrain to reach VA\VL
Decussate over quadrageia to medial leniscus to VA\VL nuclei in thalamus
Which peduncle provides the only connection to the cortex
Middle peduncle
What does the primary fissure seperate?
Anterior & posterior lobe
What separates the posterolateral fissure?
Separates posterior & flocculondular lobes
Tonsil - where is it located
Superior to forament magnum
How can the tonsil herniate?
Increases intercranial pressure
Flocculonodular\Vestibulocerebellum\Archiocerebellum Lobe
Function:
Input:
Output:
Function: Vestibular function, regulates balance, stabilization of eyes during head movements
Input: Vestibuli apparatus\nuclei (Inferior peduncle), ipsilateral
Output: Vestibuli apparatus\nuclei through inferior peduncle
Spinocerebellum or Paleocerebellum
Function:
Input:
Function: Adjust muscle tone & movement
Input: Spinal cord
Cerebrocerebellum\Pontocerebellum\Neocerebellum
Function:
Input:
Function: Planning, initiation & learning new movements
Input: Contralateral cortex through the pontine nucleus
Name the 3 deep cerebellar nuclei
F-I-D
Fastigial nucleus
Interposed nuclei
Dentate nucleus
Role of the cerebellar nuclei
Integrate cerebellar output to white matter
Fastigeal Nucli
Input
Location:
Input: Vermis
Location: Spinocerebellum
Interpossed Nuclei
Input:
Location:
Input: Intemediate zone of cortex
Location: Cerebrocerebellum
Detate Nuclei
Output:
Location:
Output: Superior peduncle (decussate in tn the midbrain)
Location Cerebrocerebellum
Three layers of Cerebellar cortex
- Granular Layer
- Purkinje Layer
- Molecular Layer
5 different cell types
P-I-G-M-C P. Purkinje Cells I. Inhibitory Neurons G. Granular cells M. Mossy Fibres C. Climbing Fibres
Name 2 cells that provide input?
How do they differ?
- Mossey Fibres
Input from cerebral cortext through cortico-pontinie-
cerebellar fibres
1 cell terminates on many fibres - Climbing Fibres
Input from inferior olive through inferior peduncle
1 cell terminates on 1 to 2 purkinje fibres (more specific)
What is the role of the granular cells?
Recieve input from mossy fibres and synapse with purkinje cells in molecular layer.
They have weak signals so many of their parralel ibres must be activated siultaously to have an effect
What layer do granular cells synapse with mossy fibres
Granular Layers
Name the cell that provides output from cerebellum?
Purkinje fiberes
Where do purkinje fibres terminate?
Vestibuli nuclei or Deep Cerebellar Nuclei (F-I-D)
Name the inhibitiry nuclei
Basket cells
Golgi nuclei
Stellate cells
What NT do all 5 of the cell types except granular cells use?
GABA = inhibitory
What NT do granular cells use?
Glutamate = ecitatory
Define Inhibitory Sculpting
Output from the cerebellum is modified by inhibitory signalas from purkije fibres
What synapse is the most important for learning & memory or error correction?
Granular cell parrelles fibres & purkinje fibres
How does short term error correction differ from long term motor learning (error correction)?
Short Term
- Few minutes
- Local inhibition
Long Term
- 30 minutes
- Change in the synthesis of membrane receptors
Describe synaptic depression or error correction (high level)
- Pontine nucleus recognizes error and activates climbing fibers
- Climbing fibers synapse with Purkinjee Fibres
- Parallel fibers of granular cells that synapse with the same Purkinjee Fibre will be inhbited if their signal arrives at the Pur. Fiber at the same time as the error signal from the climning fiber arrives
Describe synaptic depression or error correction (molecular level)
With synaptic depression
- Ca enters the purkinjee fiber due to climbing fiber activation AND Glu receptors are activated by Parrelel fibres from granular cells
- These 2 signals together activate protein kinase C
- PkC phosphorylates AMPA receptors which are then internalized so it results in a decreased response the next time the cells are activated
Example of Long term motor learning
Correction of VOR following vestibular damage
Name the three main functional regions of the cerebellum
- Spinocerebellum
- Cerebrocerebellum
- Vestibulocrebellum
Spinocerebellum
Function
Input
Output Nuclei
Function: Regulates muscle tone & execution of movement
Input: Proprioceptive, visual & auditory Information
Output:
1. Vermis purkinje fibres that go to FASTIGIAL NUCLEUS
2. Intermediate zone purkinje fibers go to INTERPOSED NUCLEI
Spinocerebellum
Input
Name pathways\tracts that provide input
Which peduncle do the inputs arrive through
Spinocerebellar pathway Dorsalspinocerebellar (lower limb) Cuneocerebellar (upper limb) Visual information Auditory information
Inferior Peduncle
Spinocerebellum Output pathway 1 Which fibers? Which peduncle? Which side? Which nucleus? Where does the nucleus send signals
Purkinje fibers in the vermis Inferior peduncle Ipsilateral side terminiate of Fastigile nucleus Nucleus sends signals to - Thalamus and then cortex - Vestibuli nuclei - Brainstem (bilateral, influences descending pathways) - Reticular formation
Spinocerebellum - Output pathway 2 Which fibers? Which side? Which nucleus? Where does the nucleus send signals through which peduncle?
Purkinjee fibers in the intermediate zone
Ipsilateral
Interposed nucleus
Contra lateral red nucleus = influence trunk muscles activity through corticospinal tract
Cerebrocerebellum
Steps & decussation in INPUT pathway
Cerebral Cortex (through ipsilateral corticospinal tract)
Pontine Nuclei (transverse pontine fibers)
Decussation in pons
Middle cerebellar peducnce
Cerebrocerebellum
Steps & decussation in INPUT pathway
Cerebral Cortex (through ipsilateral corticospinal tract)
Potine Nuclei
Decussation in pons
Middle cerebellar peducnce
Cerebrocerebellum
Steps & decussation in OUPUT pathway
Purkinjee Fibres
Ipsilateral Dentate nucleus
Superior Peduncle
Ducussate in the midbrain
Thalamus VL OR Red Nucleus
Corex OR Inferior Olive
Decussate in medulla
Inferior peduncle
Cerebrocerebellum
Define molleret triange
Two points of decusation
Disruption = incordination
Red nucleus to Cerebellum (Denate nucleus) to Inferior Olive
Cerebrocerebellum
Name the pathway between red nucleus to inferior olive
Dentatorubral tract
Cerebrocerebellum
Name the pathway between thalamus to cortex
Dentatothalamic tract
Vestibulocerebellum
Function
Input
Output
Function: Balance & reflex eye movement
Location: Flocculonodular
Input: Vestibular apparatus & nuclei
Output: Ipsilateral vestibular nuclei
Vestibulocerebellum
Input pathway
Vestibular apparatus & nuclei
Inferior cerebellar peduncle
Terminate ipsislaterally as mossy fibers
Vestibulocerebellum
Ouput pathway
Purkinjee fibers exit through inferior peduncle
Terminate on ipsilateral vestibular apparatus & nuclei
Influence vestibulospinal and vestibulo-ocular reflex
Which Purkinjee Fibers are the only ones that do not terminate on the Deep Cerebellum Nuclei
Vestibulocerebellum
