Cerebellum Flashcards Preview

Neuroscience III > Cerebellum > Flashcards

Flashcards in Cerebellum Deck (82)
Loading flashcards...
1

Reactive postural control

Mvmt is a response to unexpected perturbation.

2

Anticipatory postural control

Mvmts made to stabilize trunk prior to pre-planned limb movements. 50 msec before prime movers.

3

Neural systems for reactive/anticipatory movements

Spinal cord (simple stretch responses)
Brainstem (longer latency responses)
Basal Ganglia, Cb
Cortex

4

Open loop

Mvmt done without any sensory feedback to adjust mvmt in real time.
Faster

5

Closed loop

Slower mvmts using sensory feedback to adjust while mvmt is ongoing.
Slow ≥ 100 msec duration.

6

How does Cb fit into the brain's composition?

10% of volume, 50% of total neurons

7

How many anatomical parts?

Ant and Post lobes, & flocculonodular lobe

8

What separates Ant & Post lobes of Cb?

Primary fissure

9

What does Post-Lat Fissure of Cb separate?

Flocculonodular from Post Lobes

10

Functional Subdivisions of Cb

Vestibulo-Cb, Spino-Cb, Cerebro-Cb

11

Vestibulo-Cb

Flocculonodular lobe. Reciprical connections from Vestib system

12

Spino-Cb

Vermis (rel: trunk) & paravermal area of Ant & Post lobes (rel: limbs). Major afferents from spinal cord.

13

Cerebro-Cb

Lat Cb hemispheres of Ant & Post lobes. Major afferents from Cerebral Cortex (indirectly).

14

What are 5 classes of Cb afferents?

1 Vestib System
2 Cerebral Cortex
3 Spinal Cord
4 Visual Afferents
5 Inf Olivary Nucleus

15

Vestib System Inputs

Ipsilateral.
Vestib Nuclei (Medulla) & direct from CN VIII --> Vestibulo-Cb

16

Cerebral cortex Inputs

Contralateral.
Cortex (mainly motor & sensory areas) --> Synapse in Pontine nuclei (basal pons) --> Pontine axons cross midline and exit via Middle Cb Peduncle --> All parts of Cb

17

Spinal Cord inputs

Ipsilateral.
From 4 diff SC-Cb tracks via Inf Cb Peduncle.
exit via inferior Cb peduncle --> Vermis & Paravermal hemisphere.
Carries unconscious proprioception info

18

Visual afferent inputs

Visual cortical areas & Sup Colliculus via Pontine Nuclei
Carries visual proprioceptive info and info re: targets

19

Inferior Olivary Nucleus inputs

Contralateral.
ION is in Rostral Medulla. Important in Motor Learning. Source of Climbing fibers projections off purkinje cells to all Cb.

20

Which cells in Cb cortex project to deep Cb nuclei?

Purkinje cells

21

Which functional system uses Fastigial Nucleus?

Vermal part of Spino-Cb
F --> trunk

22

Which functional system uses Globose & Emboliform Nucleus?

Paravermal part of Spino-Cb
G&E --> limbs

23

Which functional system uses Dentate Nucleus?

Lateral Hemishpere (Cerebro-Cb)

24

What acts as the deep nuclei for Vestib-Cb?

Vestibular nuclei

25

Efferents of Vestib-Cb

Vestib Nuclei --> vestib sensors in inner ear via CV VIII

26

What does Vest-Cb coordinate?

Eye mvmt (VOR, saccades) via vestib nuclei projections.
Balance reactions & postural control via vestib-spinal & reticulo-spinal tracts.
Flocculus: smooth pursuit & adaptation of VOR gain.

27

What is the fxn of spino-Cb division?

dynamic control of ongoing mvmnt
compares intended motor plan with execution to detect error and send info. to correct plan

28

Describe the efferent pathway to spino-Cb:

efferent copy from motor cerebral cx crosses at pons and exits via middle Cb peduncle

29

Describe the afferent pathway from spino-Cb

spino-Cb tract project out from DCN through superior Cb peduncle to CONTALATERAL thalamus --> motor/pre-motor cx

30

Describe the firing of neurons in the spino-Cb:

fire during mvmnts and firing rates tend to change as mvmnt evolves

31

The vermis is involved in control of:

(F)
trunk mvmnts
saccades

32

The paravermal hemispheres control

limb mvmnt (G & E)

33

What is the fxn of cerebro-Cb?

PREDICTIVE CONTROL
- plan/prep mvmnt
- high level internal feedback circuit to regulate cortical mvmnt programs
- evaluation of sensory info for complex tasks
- coordinate skilled and visually guided behavior

34

What is the major non-motor fxn of cerebro-Cb?

ability to judge passage of time and some language fxns

35

Afferents to cerebro-Cb are from:

contralateral cerebral cx
(motor, premotor, sensory, parietal)

36

The cerebro-Cb uses afferent data to:

schema of the body
(joint position, muscle tension)
in order to anticipate what is needed for mvmnt to occur from that starting state and to update motor programs

37

Describe the efferent pathway from cerebro-Cb:

(similar to spino-Cb)
CONTRALATERAL motor and premotor cortex via thalamus / superior Cb peduncle

38

The lateral Cb is involved in coordinating visually guided behavior because:

there is a large visual input to the cerebro-Cb

39

________ efferents are used as a feedback loop to update motor plants in Cb and cx.

cerebro-Cb

40

Typical motor impairments associated with Cb lesions:

hypermetria
overcorrection
decomposition of mvmnt (loss of smooth mvmnt)
impaired intersegmental coordination
impaired balance (if midline lesion)
impaired adaptation

41

Cb lesions can manifest in impaired...

reactive and anticipatory control in trunk and limb mvmnts

42

What is a motor set?

requirements to form a planned mvmnt
calculated based on prior experience, current context for mvmnt, and current sensory-motor state (body scheme, posture)

43

What components of a motor set does the cerebro-Cb coordinate?

timing
amplitude
agonist/antagonist
coordination of limb segments

44

With damage to cerebro-Cb, what happens to the motor plan?

cannot be calibrated and updated
... leads to ataxia

45

Ataxia is associated with:

breakdown of mvmnt resulting in decomposition of mvmnt (because no longer have cerebro-Cb to calibrate and update motor plan)

46

With cerebro-Cb damage, accuracy breaks down (hyper metric), so much more dependent on:

conscious sensory feedback for error correction (snow balls though, bc the error correction is also hyper metric)

47

What fxnal subdivision acts as "error detector" to modify ongoing mvmnts?

spino-Cb

48

Spino-Cb lesion can lead to:

hypermetric mvmnts
decomposition of mvmnt (mvmnt breaks down into segments)

49

Define ataxia:

general word - describes combined influence of Cb dysfxn on gait, posture, patterns of mvmnt

50

Lesions of Cb produce typical patterns of:

incoordination
impaired balance
decreased muscle tone

51

What areas of the Cb are responsible for motor learning and adaptation?

all of Cb!!

52

With removal of flocculus or ION, what is the result?

certain adaptations to certain reflexes cannot be learned

53

With ION removal, what is the result?

certain conditional reflexes cannot be learned or maintained

54

All parts of Cb are essential to trial and error adaptation of motor behavior to:

new contexts
adaptation depends on activity.. one motor program is adapted to a new set of task requirements

55

What is the role of ION in motor learning?

ION is considered the "coach"
(Cb is the "learner)
climbing fiber input facilitates motor learning

56

With Cb damage, what is the key to rehabilitation?

REPETITION
practice and repeat in order to relearn and adapt

57

Which area of Cb is particularly important for maintaining static and dynamic balance?

all of Cb ... but particularly flocculunodular lobe
helps keep COM over moving BOS using both anticipatory and feedback mechs

58

The Cb modulates rhythmical output during gait cycle via connections with:

vestibular nuclei via flocculunodular love
(these DCN's activate extensors)

59

What interconnections does the Cb count on for coordinated response for balance rxns and postural control?

vestibular system
reticulospinal system

60

The Cb adapts locomotor pattern in novel situations especially ones requiring visual guidance by recruiting which fxnal subdivision in particular?

cerebro-Cb

61

Cb lesion often results in what muscle tone changes?

hypotonia and hyporeflexia
(mechanism is thought to involve change in Cb-reticular formation spinal cord circuits)

62

Describe differences you might observe in a pt. with lateral lobe lesion vs. medial lesion:

lateral: more difficulty with accurate limb placement
medial: more difficulty with balance

63

Define adiodochokinesia:

rapid breakdown of alternating mvmnts

64

Deficits are seen _______ to the Cb lesion.

ipsilateral

65

Isolated damage to flocculonodular lobe can lead to:

impaired smooth pursuit
gaze-evoked nystagmus
impaired VOR and VOR cancellation
impaired balance

66

Isolated vermis damage can lead to:

dec. muscle tone
postural tremor, trunk ataxia
ataxic gait
balance impairment
hypermetric saccadic and smooth pursuit eye mvmnts

67

Isolated vermis damage does NOT affect:

the limbs (no influence on imv tremor or limb ataxia) --> because the vermis is central

68

Damage to the lateral hemisphere will result in:

limb mvmnt deficits
decreased muscle tone
limb ataxia
hypermetria
decomposition of mvmnt

69

Describe how tremor may present in an individual with midline Cb lesion vs. lateral Cb lesion:

medial: postural tremor
lateral: limb intention tremor

70

Ataxic gait is characterized by:

dec. angular excursions of multiple joints
varied stride length
abnormal timing of limb segments
reduced walking speed

71

Abnormal timing of limb segments is associated with:

decomposition of mvmnt

72

Varied stride length is associated with:

loss of rhythmical control of step cycle

73

Dec. angular excursions of multiple joints during ataxic gait is an adaptation to:

attempt to dec. DOF and inc. stability

74

Decomposition of speech is called:

dysarthria
"scanning speech"

75

Define asthenia:

generalized weakness associated with Cb disorder

76

Global mvmnt deficits related to Cb dysfxn include:

loss of anticipatory control
dymetria
inc. reaction time
decomposition of mvmnt
tremor
ataxic gait
dysarthria
rebound phenomenon
asthenia
hypotonia
adiadochokinesia

77

With Cb damage, which system remains intact?

conscious sensation intact

78

What are some common clinical tests for Cb fxn?

finger to nose
finger to PT's finger
finger to finger
alternate nose to finger
finger opposition
mass grasp
pron/sup
rebound test
tappoing hand or foot
heel on shin
draw a circle

79

What are common pathologies that affect the Cb?

tumors
stroke
acoustic neuromas
trauma
MS
Ataxia (Fredrich's, degenerative, genetic)
chronic alcoholism

80

What vasculature supplied portions of the Cb?

PICA --> post. lobe
AICA --> vest. lobe
SCA --> ant. lobe

81

Chronic alcoholism especially affects which lobe?

anterior

82

Considerations for effective intervention planning with Cb damage?

capacity for motor learning
capacity for adaptation for task modification
adaptation to new environmental contexts
coordination of agonist/antagonist pairing for multi-limb mvmnt