Cerebellum [Guest Lecture] Flashcards
List the 6 functions of the Cerebellum
- Balance
- Feedback/forward
- Sensory info integrated into movement
- Timing
- Motor learning
- Adjustment
List the 3 lobes and 3 vertical sections of the cerebellum
Lobes: anterior, posterior, flocculonodular
Vertical sections: midline vermis, paravermal (medial) hemisphere, latearl hemisphere
Describe the 3’s of the cerebellum
3 layers of outer cortex (gray matter)
Deep cortex (white matter)
3 pairs of cerebellar nuclei
Also: 3 lobes, nuclei, and peduncles
List the 3 pair of cerebellar nuclei
- Fastigial
- Interposed (globose and emboliform)
- Dentate
List the 3 cerebellar peduncles
- Inferior (largely input, some output to vestibular/reticular)
- Middle (input only)
- Superior (largely output to cortex, red nucleus, reticular)
Structure: Only output of cerebellar cortex
Purkinje cells
List the 2 input cell types of the cerebellum
Climbing: synapse directly with purkinje cells
Mossy: do not contact purkinje cell directly
Fiber: Carry motor plan from cerebrum to cerebellum
Climbing fibers
Cell: Carry peripheral sensation to cerebellum
Granule cell
Structure: Parallel fiber complex
Mossy fibers
Describe the arrangment of climbing fibers
- Synapse direclty on purkinje cells
- Their firing causing firing of purkinje cells
- Each purkinje receives input from 1 climbing fiber
- Each climbing fiber contacts 1-10 purkinje neurons
Describe mossy fibers
- Have a DIVERGENT influence on cerebellar function
- DO NOT contact purkinje fibers directly
- Synapse on: granule cells, golgi cells, stellate cells, basket cells
- INHIBITORY effect on granule and purkinje cells
- PARALLEL fibers run along top of purkinje fibers
- Pass through several hundren thousand purkinje cells
Describe the influence of climbing and parallel (mossy) fibers on perkinje cells
Both are EXCITATORY
Single AP from climbing = purkinje depolarize
Weaker influence from paralle fibers,
Climbing fibers act to “teach” purkinje cells how to response to particular patterns of parallel fiber (sensory) inputs – to the point where CNS info is no longer needed to make quick adjustments ex. walking
Corresponding area: cerebrocerebellum
Latearl hemisphere of cerebellum
hand, arm, foot, leg
Corresponding area: Vermis and Paravermis hemisphere
Spinocerebellum
Corresponding area: Flocculonodular lobe
Vestibulocerebellum
Portion of Cerebellum:
Contorls extension and proximal mm
Important for posture control/balance
Coordinates eye and head movement (VOR)
Descending tracts of vestibulocerebellum – flocculonodular lobe and vermis
Portion of Cerebellum:
Primarily influence limb movement
Compares commands from M1 to actual position/velocity of moving part and can issue correcting signals
Descending tracts of spinocerebellum – paravermal hemisphere
Describe the input and output of the descending spinocerebellar tract
Input: from motor cortex to SC
Output: via interposed n. through VL/VA of thalamus to M1/Red nucleus
Portion of Cerebellum:
Involved in planning and programming of voluntary, learned, skillful movement by influencing output of the motor cortex
Descending trat of the cereberocerebellum – lateral hemisphere
Describe the input and ouput of the descending cerebrocerebellar tract
Input: from widespread areas of the cerebral cortex to the pontine n.
Output : via dentate n. to VL/VA of thalamus to premotor/motor cortex
Describe how the cerebellum is a “double cross”
The output from the cerebellum crosses to the contralateral thalamus/red nucleus/motor cortex. Those tracts cross to the contralateral side when they descend
Thus cerebellar lesions typically effect the ipsilatera side
The cerebellum serves the SAME SIDE of the BODY
Function: Descending Vestibulocerebellar Tract
Control of extnesion and prox mm
Balance and posture control
VOR
Function: Descending Spinocerebellar Tract
Compares commands from motor cortex with actual position/velocity of moving part and can issue correcting signals
Function: Descending Cerebrocerebellar Tract
Involved in planning and programming voluntary, learned, skilfull movement by influencing the output of the motor cortex
Area of Damage:
Balance disorders
Ataxia
Full control of limbs in supine
Shaking due to constant adjustment attempts
Vestibulocerebellum and vermis
Area of Damage:
Loss of eye control
Difficulty with pursit eye movement
Difficulty with accurate voluntary eye movement
Vestibulocerebellum
Describe the presentation of an individual with damage to their:
- Vestibulocerebellum and vermis
- Vestibulocerebellum
- Balance disorders, ataxia, shaking, full control of limbs in supine
- Loss of eye control
Describe why those with vestibulocerebellar and vermis damage still have limb control in supine
Because the cerebrum/lateral cerebellar hemisphere are still in tact
Area of Damage:
- Disruption of accurate execution of movement
- Hypotonia (decreased corticospinal and rubrospinal tract activity)
- Dysmetria
- Ataxia
- Intention tremor
- Pendular reflex
Spinocerebrum and paravermis hemisphere
Term: Disrupted accuracy of reaching b/c of increased erros in timing components of movement
Dysmetria
Term: Poor coordination of joints
Ataxia
Term: correction of errory
Intention tremor
Term: reflex disruption
Pendular reflex
Describe the presentation of an individual with spinocerebellar/paravermis damage
- Disrupted accuracy of movement
- Hypotonia
- Dysmetria
- Ataxia
- Intention tremor
- Pendular reflex
Area of Damage:
Errors in movement timing
Delays in initiating movements
Increased reaction time
Disrupted sequential movements
cerebrocerebellum and lateral cerebellar hemispheres
Term: disrupted sequential movements
decomposition of movements
Describe the presentation of an individual with cerebrocerebellar and lateral cerebellar hemisphere damage
- Errors in movement timing
- Delays in initiating movements
- Increased reaction time
- Decomposition of movement
Term: Inability to perform rapid alternating movements
Dysdiadochokinesia
Term: How a behavior was accomplished and it’s outcome
Feedback
Term: Prediction about what is coming
Feedforward
Describe the result of feedforward information
- allows precisely timind movements
- importantfor multi-joint movement - controls relative timing
Describe the 2 cerebrocerebellar loops and their role in motor learning
Loop 1 = thalamus to premotor and primary motor areas
Loop 2 = red nucleus to inferior olivary nucleus and back to controlateral cerebellum forming feedback loop
Feedback loop pathways suports MENTAL REHEARSAL of movements and motor learning
Describe the paravermis role in motor learning
Incorporates error related feedback into up coming movements during motor learning
Describe the role of the cerebellum during learning
- Active early during acquisition of motor skills
- Chunk information to when learning a series of movements
- Allows for advanced preparation
- Important for feedback and feedfoward processes
Term: allows a series of movements to be learned and smoothed over time
Chunking
Describe the role of the cerebrocerellum in cognition
- input to cerebrocerebellum exculsively form cerebral cortex
- Interconnected with working memory regions
- Dentate n. important in acquiring and processing sensory info for tasks requiring complex spatial and temporal judgments
- Lateral hemisphere associated with: word learning, silent reading, pegboard puzzle solving
Portion of Cerebellum: Functions for feeback
Paravermis
Portion of Cerebellum: Functions in controlling motor tone
Vermis
