Task 3 - Cerebellum

Question 1

function cerebellum

Answer 1

• balance (inner ear)
• smooth movements
• if not, it corrects them
• equilibrium (inner ear)
• muscle tone (proprioceptive info used)
• coordination (info from motor areas in cortex)
• motor learning

Question 2

parts of cerebellum (3)

Answer 2

1) cerebrocerebellum
2) Spinocerebellum
3) Vestibulocerbellum

Question 3

Cerebrocerebellum

Answer 3

-lateral cerebellar hemisphere
-Input: directly from cortex
-regulation and guidance of highly skilled movements
(planning and execution of complex spatial and temporal sequences of movement)

Question 4

Spinocerbellum

Answer 4

• median (vermis) and paramedian (more lateral) zone of hemisphere
• input: from spinal cord

-paramedian zone: movement of distal muscles
(info from upper and lower extremities)

-vermis: movement of proximal muscles and certain eye movements
(vermis gets sensory info from trunk head neck)

Question 5

Vestibulocerebellum

Answer 5

• caudal-inferior lobes ( flocculus and noduclus)
• input: vestibular nuclei in brainstem
• regulation of movement underlying posture equilibrium and vestibulo-ocular reflex (fix eyes on object and move head -> object is fixed, eyes stay fixed) and balance

Question 6

Pathways (cerebellar peduncles - 3)

Answer 6

1) superior cerebellar peduncle/brachium conjunction
2) middle cerebellar peduncles/brachium pontis
3) Inferior cerebellar peduncles/ restiform body

Question 7

Superior cerebellar peduncle/ brachium conjunction

Answer 7

• almost entirely efferent pathway
• Location: neurons that give rise to this pathway are in the deep cerebellar nuclei
• Deep Cerebellar Nuclei -> Dorsal Thalamus -> Pre-Motor and Primary Motor
• Deep Cerebellar Nuclei -> Superior Colliculus

Question 8

middle cerebellar peduncle/ brachium pontis

Answer 8

• affarent, contralateral
• most areas of cortex and superior colliculus -> cell bodies in pontine nuclei of pons -> transverse pontine fibers cross via middle cerebellar peduncle -> cerebellar cortex and deep nuclei
• one of largest pathways in NS

Question 9

inferior cerebellar peduncle/ restiform body

Answer 9

• smallest but most complex
• affarent pathways: axons from vestibular nuclei (balance, posture) and tegmentum
• efferent: project to vestibular nuclei and reticular formation

Question 10

affarent vs efferent

Answer 10

affarent -> empfangen, sensorisch

efferent -> agieren , motorisch

Question 11

4 major deep nuclei in each cerebellar hemisphere

Answer 11

1) Dentate nucleus
2) Two interposed nuclei
3) Fastigal nucleus

Question 12

Dentate nucleus

Answer 12

• largest nucleus in humans
• receives most input from cerebrocerebellum
• > projects mostly to premotor and association cortices
• > motor planing

Question 13

Two interposed nuclei

Answer 13

• most input from spinocerebellum
• to motor cortex and brainstem
• > motor execution

Question 14

Fastigial nucleus

Answer 14

• input from spinocerebellum
• to motor cortex and brainstem
• > motor execution

Question 15

Cerebrocerebellar pathway

Answer 15

• to dentate nucleus
• decussates at superior cerebellar peduncle
• ascends to thalamus
• then to premotor area
• motor planning

Question 16

Spinocerebellar pathway starting interposed nucleus

Answer 16

• interposed nucleus
• > project via superior peduncle
• > to thalamus
• > frontal lobe
• motor execution

Question 17

Spinocerebellum starting at fastigial nucleus

Answer 17

• fastigial nuclei (vermis)
• > inferior peduncle
• > reticular formation (spinal cord)
• > vestibular complex
• > proximate limb muscles

Question 18

Vestibulocerebellar pathway

Answer 18

• inferior peduncle
• > vestibular complex
• movement of eyes, head, neck

Question 19

Inputs to cerebellum

Answer 19

• cortex
• spinal cord and medulla
• trigeminal complex
• vestibular nuclei

Question 20

Input from cortex

Answer 20

• via pontine nuclei (Pons)
• > to cereberocerebellum
• contralateral

Question 21

spinal cord and medulla input

Answer 21

• to spinocerebellum
• innervated by proprioceptive axons from lower and upper body parts respectively

-proprioceptive: sense of self-movement and body position

Question 22

Trigeminal complex input

Answer 22

• to spinocerebellum

- proprioceptive signals from the face

Question 23

input vestibular nuclei and axons from 8th cranial nerve ( inner ear to brain)

Answer 23

-to vestibulocerebellum
-info from ear
-

Question 24

input from inferior olive and locus coeruleus

Answer 24

• in brainstem

- > learning and memory function

Question 25

Timing Hypothesis

Answer 25

- cerebellum critical for sensorimotor learning - generates predictions that are temporally precise - cortical areas select effectors while cerebellum supplies the precise timing - lesions are most disruptive to highly practiced movements - > present greatest need for precise timing

Question 26

cerebellum contralateral ?

Answer 26

In contrast to the cerebral hemispheres, the left side of the cere- bellum is concerned with movements of the left side of the body, and the right side of the cerebellum is concerned with movements of the right side.

Question 27

3 layers of cerebellum (from outside to inside)

Answer 27

- molecular level (basket cells, stellate cell, parallel fibers) - purkinje layer - granule layer

Question 28

stellate cells and baskets cells

Answer 28

- activated -> release inhibitory neurotransmitters | - inhibit purkinje cells

Question 29

neural activity in cerebellum

Answer 29

- cerebellar cortex and deep cerebellar nuclei have spontaneous activity during rest - during movements both are mainly active during movement changes

Question 30

cerebellar lesions and diseases - in general

Answer 30

-difficulty in producing smooth and coordinated movements = cerebellar ataxia (disruption of role in correction of errors in ongoing movements) -damage always on same side as lesion (ipsilateral) -

Question 31

alcohol abuse leads to.. in cerebellum...

Answer 31

- degeneration in anterior portion of cerebellar cortex | - affects movements in lower limbs

Question 32

Damage to vestibulocerebellum

Answer 32

- impairs ability to stand upright and maintain direction of gaze - disruption of pw to vestibular nuclei -> reduction in muscle tone

Question 33

Damage to spinocerebellum

Answer 33

- difficulty controlling walking movements and alternating movements - > hypermetric movements: movements that extend beyond the intended target

Question 34

Lesions of cerebrocerebellum

Answer 34

-impairments in highly skilled sequences of learned movements (speech, playing a musical instrument)

Question 35

Article: disruption of state estimation in the human lateral cerebellum (Miall) what is meant by state estimation process?

Answer 35

- cerebellum crucial for estimation process - > combines info from efferent motor signals and sensory afferent signals of the motor system - sensory info reaches brain only after short delay, muscle may already be in motion - brain must calculate 'state estimate' by combining sensory info about last known position of muscle with predictions of its responses to recent movement commands - > used to accurately plan and control movement

Question 36

Article: disruption of state estimation in the human lateral cerebellum (Miall) -method and findings

Answer 36

- using TMS -> interrupting several separate areas in the brain as participants reached a target - stimulation over cerebellum caused reaching error whereas stimulation to other brain areas did not disrupt reaching direction - > induced error due to disruption of state estimation process within ipsilateral cerebellum (TSM between go cue and reach-to-target movement) - reaching movement was inaccurately planned

Question 37

ataxia and forward model

Answer 37

- people with ataxia have ability to select right movements in right sequences but still lack coordination - forward model is not intact (not synchronized with ongoing sensory signals)