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202: Theme 2, Sensory inputs and motor outputs > Cerebellum and motor learning > Flashcards

Cerebellum and motor learning Flashcards

1
Q

Cerebellum function [4]

A

Maintains balance and posture

Co-ordinates voluntary movements
- Compares movement intended to movement actually occuring

Motor learning

Cognition

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2
Q

Cerebellar peduncles

A

Connects the cerebellum to the midbrain.

Three sections:

  • Superior: output to the cerebral cortex via thalamic nuclei
  • Middle: Connects to the pons via pontine nuclei
  • Inferior: Spinocerebellar tract and inferior olive fibres
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3
Q

Lobes of the cerebellum

A
  • Anterior
  • Posterior
  • Flocculonodular
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4
Q

Vestibulocerebellum

A

Functional division of the cerebellum
- Located in the flocculonodular lobe

Function:
- Contains vestibular nuclei involved in balance and eye movements

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5
Q

Vestibulocerebellum pathways

A

Inputs:

  • Receives from the semicircular canals of the ear
  • Receives afferent fibres from the vestibular nuclei.

Outputs:

  • Sends fibres to the vestibular nuclei
  • Medial vestibular nuclei leads to vestibulospinal tract
  • Lateral vestibular nuclei branches synapse at extra-occular muscle nuclei
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6
Q

Spinocerebellum

  • Structure
  • Function
A

Composed of the vermis and paravermis- contains two somatotopic maps of the body
- Vermis: Fastigial nucleus—-> medial descending systems

  • Paravermis: interposed nucleus—> lateral descending systems

Function:
- Motor execution: controls muscle tone and posture

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7
Q

Spinocerebellum paths

A

Inputs:
- Spinocerebellar tracts

Outputs:

  • Reticulospinal tract
  • Vestibulospinal tract
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8
Q

Cerebrocerebellum

  • Structure
  • Function
A

Composed of the lateral aspect of the cerebral hemispheres.
- Contains dentate nucleus

Function:
- Dentate nucleus communicates with cortical areas 4+6= motor planning

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9
Q

Cerebrocerebellum paths

A

Input
- Corticopontine tract [primary motor cortex to pontine nuclei]

  • Pontocerebellar tract [pontine nuclei to cerebellar cortex]

Output

  • Cortex to dentate nuclei
  • Dentate nuclei to thalamic nuclei
  • Thalamus to primary motor cortex
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10
Q

Lobar anatomy of cerebellum

A

Vermis
- Contains fastigial nucleus

Paravermis
- Contains interposed nucleus

Hemisphere
- Contains dentate nucleus

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11
Q

Superior cerebellar peduncle pathways

A

Exit for outputs to:

  • Thalamus [ from dentate nucelus]
  • Red nucleus [interposed nucleus]
  • Vestibular nuclei [fastigial nucleus]
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12
Q

Middle cerebellar peduncle pathways

A

Contains input from the pontocerebellar tract [from corticopontine tract]

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13
Q

Inferior cerebellar peduncle pathways

A

Allows entry of outputs from:

  • Inferior olive tract
  • Spinocerebellar tract
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14
Q

Dysmetria

A

Type of ataxia

  • Lack of co-ordination
  • Overshoot or undershoot for the intended position of: hand, arm, leg, eye.
  • Movement is not stopped in time
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15
Q

Dsynergia

A

The inability to conduct complex movements

- Movements are uncoordinated and abrupt

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16
Q

Dysdiadochokinesia

  • Defintion
  • Location of lesion
A

Type of ataxia

Reduced ability to conduct rapidly alternating movements
- Lesion in cerebellar hemisphere or frontal lobe

17
Q

Intentional tremor

A

Tremor that arises when trying to perform a visually guided or deliberate movement.

Caused by lesion in vestibular nuclei [i.e in the superior cerebellar peduncle]

18
Q

Dysarthria

A

Incoordination of the respiratory muscles
- Of the larynx, etc

Causes unclear articulation of speech

19
Q

Vestibular-ocular pathway

A

Pathway from the vestibular apparatus in the ear to the extra-ocular muscles

  1. Vestible—> CN VIII–>vestibular nucleus in the pons
  2. Fibres from the vestibular nucleus crosses —-> enters abducens nucleus
  3. Abducens nerve from the nuclei—> lateral rectus
  4. Fibres from abducens nuclei—> occulomotor nuclei—-> medial rectus
20
Q

Nystagmus

  • Definiton
  • Pathway lesion
A

Involuntary, rhythmic, oscillations of one or both eyes
- In all directions of views

Prevents eye fixation

Can be caused by lesion of the vestibulocerebellar pathway

21
Q

Spinocerebellar tract lesion effects

A

Gait ataxia
- Unsteady walking

Hypotonia of the limbs and posture

22
Q

Cerebellar inputs and outputs

A

Inputs:
- Mossy fibres: from brainstem [pontine, middle cerebellar peduncle] and spinal cord [spinocerebellar tract, inferior cerebellar peduncle]

  • Climbing fibres: from inferior olivary nucleus in brainstem.

Outputs, from deep cerebellar nuclei, via superior cerebellar peduncle:

  • Thalami
  • Vestibular nuclei
  • Red nucleus
23
Q

Cerebellar cortex layers

A

Molecular layer

Purkinje cell layer
- Contains many parallel fibres to each cell

Granule cell layer
- Contains granule cells and golgi cell

White matter layer

  • Contains moss fibres and climbing fibres
  • Climbing fibre to one purkinje cell but contains many synapses
24
Q

Inputs and outputs of the Purkinje cells

A

Inputs

  • Convergence from parallel fibres [from granule cell] to purkinje dendrites
  • One climbing fibre to a purkinje cell that diverges

Output
- To deep cerebellar nuclei

25
Q

Feedback loop - motor learning

A
  1. Desired output
  2. Erro signal—-> effector muscle—> output

Feedback signal comes from the output—> leads to correction

26
Q

Feedforward loop

A

Movements too fast to be corrected by feedback
- Done via predictions of pervious outcomes

Advanced information generates desired output —> fed foward to generate an output

27
Q

Error signals

A

Derives from sensory information

- Sent via infeiror olivary nucelus —> climbing fibres

28
Q

Genetic cause of cerebellar dysfunction

A

Frederich’s ataxia

Spinocerebellar degeneration

Ataxia-telengiectasia

Von Hippel Lindau

29
Q

Acquired symmetrical ataxia causes

A

Alcohol

Metabolic [Low B12, thyroid, ceoliac disease]

Drugs [like phenytoin]

Degenerative disease

Immune

30
Q

Cerebellar motor loop

A
  1. Axons from: Area 4 +6
    - Somatosensory cortex
    - Posterior parietal cortex
    - –> Converge into the pontine nuclei
  2. Projections of the pontine nuclei enters the cerebellum
  3. Projections from cerebellum—> ventral lateral nucleus in thalamus

202: Theme 2, Sensory inputs and motor outputs (13 decks)

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