Pratique - Cerebllum Flashcards
About the cerebellum: Volume
10% of the total volume of the brain
+ contain more than half of its neuron
Why does the cerebellum is composed of so many neurons?
Need many neurons for the adjustment during mvt => Many neurons for fast processing
ANATOMY : How is divided the cerebellum ?
In 3 lobes :
1. Anterior lobe =spinocerebellum lobe
2. Posterior lobe
3. Flocculonodular lobe = vestibular lobe
What is the function and pathway of anterior lobe of the cerebellum?
Balance & equilibrium because it’s connected to vestibular system (inner ear to -> cerebellum)
NB :anterior lobe = spino cerebellum lobe
What is the function of the posterior lobe +pathway?
Function : Receive message about motor plan and send back message to descending pathway
Trajectory = Cortex -> Post lobe -> cortex -> Descending pathway
How to enhance plasticity?
With 3 experiences :
1. Error (correction) - Cerebellum
2. Reward (goal directed -> release of Dopa)
3. Repetition - Cerebral cortex
What are the deep cerebellar nuclei?
1.Fastigial nucleus
2. Interposed nuclei
3. Dentate nuleus
What do the deep cerebellar nulcei?
They are output nuclei, and send message out from peduncle ?
What are the layers of the cerebral cortex?
(Down to up)
- Granular layer (GL)
- Purkinje cell layer (PCL)
- Molecular layer (ML)
Explain the connection in between the 3 layers of the cerebral cortex? + What’s the name of this process?
Process = Neurosharpening
1. Info comes from periphery (vestibular system, cortex..?..)
2. Send info to GL where the // fibers are
3. // fibers are connected to the Purkinje cells => Exchanges
4. Purkinje cells send message through output nuclei
5. If info is correct -> activate what they want & send back message to cortex & descending pathway
6. If info is incorrect -> purkinje cells change pattern of activation, correct error & send message to cortex.
What are the main functions of the cerebellum?
- Speech
- Eye movements & gaze fixation
- Predictive grip force control
- Excitability of the opposite M1 (“non damages”)
- Sensorimotor integration -> Can influence muscle tone
- Adapt movements & correct errors
- motor, cognition, emotion, memory & attention functions
What region control the speech in <=> cerebellum?
Controlled by superior paravernal region, the intermediate cerebellar cortex and the dentate nucleus.
Where does the predictive grip force control originates from?
Originates from the peculiar role in the anticipatory tuning of muscle activity during voluntary motor actions.
How does the cerebellum has an effect of excitability of the opposite M1?
Through the dento-thalami-cortical projections, the cerebellum has a putative facilitatory effect on excitability of the opposite m1.
How does the cerebellum has a role in the sensorimotor integration?
- Sensorimotor functions cause related to muscle spindle land golgi organ
- In feedfoward control, the cerebellum participates in pre-programming of voluntary movement.
- In the feedback controls, the cerebellum evaluates disparities btw intention and action.
- When an error is detected, the Cb output modulates descending motor system to influence muscle tone.
What are the main four main symptoms of cerebellar disorders?
- Hypotonia
- Astasia- a ASIS
- Ataxia
- Action tremor
Definition of Hypotonia ?
= Decrease in tone, diminished resistance to passive limb displacements
Definition of Astasia-Abasia?
=Inability to walked or stand
Atasia = loss of ability to maintain a steady limb or body posture across multiple joints
Atasia = loss of ability to maintain upright stance against gravity
What is the definition of Ataxia?
= abnormal execution of multi-joined voluntary movements, characterized by lack of coordination.
-> Patients have pb initiating responses with affected limb and controlling the size of a movement (days m’étira) and rate and regularity of repeated mvt
Definition of action tremor?
= result of a series of erroneous corrections of the movement. Tremo during mvt
Other symptoms of cerebral disorders
- Hypotonia and asthenia (for antagonist & extensors muscles ++)
- Fatiguability
- Dysmetria
- Rebound : exaggerated postural reaction
- Dyssynergia
- Abdormalities in timing & coupling mvt
- Cerebrall tremor (postural tremor)
- Incr. postural sway
- Gait ataxia ….
What’s the relation between the Cerebellum and the coordination?
The cerebellum is responsible for intra limb et inter-limb coordination
What’s the relation between the Cerebellum and the coordination?
The cerebellum is responsible for intra limb et inter-limb coordination
How is divided the anterior lobe of the cerebellum?
- Vermis (center
- Para-vermis (laterally, on each side of vermis)
What is the function and pathway of vestibular lobe of the cerebellum?
NB = Flocculonodural lobe
- Receive information from the semicircular canals and otolith organs. He also receive mossy fiber visual input.
- Function : Balance & equilibrium bcause it’s connected to the vestibular system (inner ear -> Cb) => affects balance & gait
- Output bypasses the deep cerebellar nuclei & proceeds directly to the vestibular nuclei in the brain stem
