MODULE 11- Modulation of Movement by the Cerebellum

Question 1

cerebellum constitutes ____% of the total brain volume

Answer 1

10%
-but contained more than 1/2 of the brain’s neurons

Question 2

T/F: the cerebellum projects directly to the motor neurons of the spinal cord

Answer 2

false

Question 3

what does the cerebellum do

Answer 3

modifies movement by regulating upper motor neurons in regions such as the motor cortex

Question 4

cerebellum is mode up of a ____ and ____

Answer 4

-cerebellar cortex
-deep cerebellar nuclei

Question 5

the cerebellum is thought to play a role in what 3 things

Answer 5

-motor learning
-error correctino
-sensory-motor integration

Question 6

how many subdivisions of cerebellum

Answer 6

3

Question 7

3 subdivisions of the cerebellum

Answer 7

-cerebrocerebellum
-spinocerebellum
-vestibulocerebellum

Question 8

cerebrocerebellum receives input from

Answer 8

cerebral cortex (via pons)

Question 9

what is cerebrocerebellum responsible for

Answer 9

highly skilled movements (ex: speech)

Question 10

spinocerebellum receives input from

Answer 10

medial, directly from spinal cord

Question 11

vermis

Answer 11

most median strip of spinocerebellum

Question 12

what is the vermis (median strip) of spinocerebellum responsible for

Answer 12

-posture
-locomotion
-eye movements

Question 13

what is the paramedian part of spinocerebellum responsible for

Answer 13

movements of distal muscles

Question 14

vestibulocerebellum receives input from

Answer 14

vestibular nuclei

Question 15

what is vestibulocerebellum responsible for

Answer 15

-balance
-vestibular reflexes
-eye movements

Question 16

see slide 4 for labeled image of 3 major subdivisions (spinocerebellum, cerebrocerebellum, vestibulocerebellum)

Question 17

cerebellar peduncles

Answer 17

thick tracts connecting the cerebellum with the rest of the CNS

Question 18

deep cerebellar nuclei

Answer 18

project to the upper motor neurons in the motor and premotor cortices via thalamus

Question 19

3 pathways between the cerebellum and other CNS

Answer 19

-superior
-middle
-inferior
cerebellar peduncles^

Question 20

3 types of deep cerebellar nuclei

Answer 20

-fastigial nucleus
-interposed nuclei
-dentate nucleus

Question 21

ALL output from the cerebellum is via

Answer 21

deep cerebellar nuclei

Question 22

how many axons in cerebellum

Answer 22

20 million axons

Question 23

how many axons in optic tract

Answer 23

1 million

Question 24

how many axons in corticospinal

Answer 24

0.5 million

Question 25

MCP provides input/output

Answer 25

input ONLY

Question 26

input to middle cerebellar peduncle

Answer 26

pontine nuclei

Question 27

output of middle cerebellar peduncle

Answer 27

cerebellar cortex/deep nuclei

Question 28

input to inferior cerebellar peduncle

Answer 28

inferior olive

Question 29

output of inferior cerebellar peduncle

Answer 29

cerebellar cortex/deep nuclei

Question 30

inferior olive is responsible for

Answer 30

learning and memory tasks

Question 31

2 sensory inputs to cerebellum

Answer 31

-spinal cord -vestibular nuclei

Question 32

what is the largest input to cerebellum

Answer 32

cerebral cortex

Question 33

how does cerebral cortex travel through cerebellum

Answer 33

travels contralaterally through middle cerebellar peduncle

Question 34

what is responsible for error signal for learning

Answer 34

inferior olive

Question 35

how does sensory input travel through inferior cerebellar peduncle

Answer 35

ipsilaterally

Question 36

how is the cerebellum organized

Answer 36

somatotopically (based on body parts) -these maps are "fractured" with multiple representations -see slide 9 for image

Question 37

cerebellar hemispheres coordinate movement of the ipsilateral/contralateral body

Answer 37

ipsilateral

Question 38

cerebrocerebellum goes to which deep cerebellar nuclei

Answer 38

dentate nucleus -which goes to premotor cortex (motor planning and motor learning)

Question 39

spinocerebellum goes to what deep cerebellar nuclei

Answer 39

interposed and fastigial nuclei -which goes to motor cortex and brainstem (motor execution)

Question 40

vestibulocerebellum goes to what deep cerebellar nuclei

Answer 40

vestibular nucleus -which goes to lower motor neurons in spinal cord and brainstem (balance and vestibulo-ocular regulation)

Question 41

what body part does superior colliculus involve

Answer 41

eyes

Question 42

dentate and interposed axons exit cerebellum via

Answer 42

superior cerebellar peduncle -and cross the midline before they synapse with the thalamus/superior colliculus

Question 43

eye movement-related neurons in superior colliculus receive input from

Answer 43

contralateral cerebellar cortex via the upper cerebellar peduncle

Question 45

superior cerebellar peduncle sends information up/down

Answer 45

UP

Question 46

inferior cerebellar peduncle sends information up/down

Answer 46

to brainstem and DOWN

Question 47

the gastigial nuclei project via ____ to ____

Answer 47

inferior cerebellar peduncle to the upper motor neurons that control axia and proximal limb muscles

Question 48

inferior cerebellar peduncle primarily contains which fibers

Answer 48

afferents + efferents -afferent fibers from the vestibular nuclei and spinal cord -as well as efferents to the vestibular nuclei and reticular formation

Question 49

middle cerebellar peduncle primarily contains which fibers

Answer 49

afferents -afferents from the contralateral pontine nuclei

Question 50

superior cerebellar peduncle primarily contains what fibers

Answer 50

efferent -efferent fibers from the cerebellar nuclei to the thalamus and superior colliculus

Question 51

neurons in the cerebellar cortex are organized into how many layers

Answer 51

3 layers

Question 52

deepest layer of cerebellar cortex

Answer 52

granular layer

Question 53

granular layer of cerebellar cortex

Answer 53

input layer -deepest layer -contains 100 billion granule cells that give rise to axons called parallel fibers that ascend to outermost molecular layer

Question 54

middle layer of cerebellar cortex

Answer 54

purkinje cell layer

Question 55

purkinje cell layer of cerebellar cortex

Answer 55

output layer -middle layer -dendrites of purkinje cells extend upward into the molecular layer where they receive input from a large number of parallel fibers

Question 56

output of purkinje cells is to

Answer 56

deep cerebellar nuclei

Question 57

outermost layer of cerebellar cortex

Answer 57

molecular layer

Question 58

molecular layer of cerebellar cortex

Answer 58

outmost layer -important processing layer

Question 59

processing layer of cerebellar cortex

Answer 59

molecular layer

Question 60

output layer of cerebellar cortex

Answer 60

purkinje cell layer

Question 61

input layer of cerebellar cortex

Answer 61

granule cell layer

Question 62

5 cell types in cerebellar cortex

Answer 62

-granule (+) -golgi (-) -purkinje (-) -stellate (-) -basket (-)

Question 63

circuits wtihin the cerebellum

Answer 63

-purkinje neuron -mossy fibers -granule cells -climbing fibers -basket, stellate, golgi cells

Question 64

purkinje neuron

Answer 64

ultimate afferent destination for cerebellar cortex

Question 65

mossy fibers

Answer 65

a major source of input from brainstem and spinal cord

Question 66

granule cells give rise to

Answer 66

parallel fibers

Question 67

climbing fibers of inferior olive synapse onto

Answer 67

purkinje cells

Question 68

basket, stellate, and golgi cells are all inhibitiory/excitatory input to purkinje

Answer 68

inhibitiory

Question 69

2 inputs to cerebellum

Answer 69

-mossy fibers -climbing fibers

Question 70

mossy fibers

Answer 70

-arise from cell bodies in the pontine nuclei, brainstem, and spinal cord -synapse (excitatory) onto granule cells, which give rise to parallel fibers which have excitatory synapses onto the dendritic spines of the purkinje cells -highly convergent- each purkinje neuron is contacted by 200,000 to 1 million granule cells

Question 71

climbing fibers

Answer 71

-arise from inferior olive -contact purkinje cells directly; also excite the deep nuclei -excitatory synapses onto purkinje cells -each purkinje cell receives numerous synaptic contacts from 1 single climbing fiber

Question 72

where do purkinje cells project to

Answer 72

deep cerebellar nuclei -these are the ONLY output cells of the cerebellar cortex

Question 73

what output from purkinje cells

Answer 73

GABAergic inhibitory output

Question 74

in the deep cerebellar nuclei, inhibitory inputs from purkinje cells converge with

Answer 74

excitatory inputs from mossy + climbing fibers

Question 75

how does cerebellum coordinate ongoing movement

Answer 75

by reducing motor error

Question 76

cerebellar circuitry and coordination of ongoing movement

Answer 76

-deep cerebellar cells and purkinje cells recognize potential errors by comparing convergent activity concurrently available to both cell types -the potential for making errors can be experimentally induced -ex: partial cutting of lateral rectus muscle in monkey eye -> cover the normal eye -> weak eye initially hypometric -> then, overtime, becomes hypermetric

Question 77

hypometric

Answer 77

person undershoots movement

Question 78

hypermetric

Answer 78

overshoots movements

Question 79

eyes and head move in what direction

Answer 79

opposite

Question 80

learned changes in vestibulo-ocular reflex in monkeys

Answer 80

normal vesitbulo-ocular reflex (VOR): -head and eyes move in coordinated manner to keep image on retina VOR out of register: -eyes move too far in relation to image movement on the retina when the head moves after several hours... VOR gain reset: -eyes move smaller distances in relation to head movement to compensate

Question 81

if cerebellum is damaged, does VOR adapt

Answer 81

no VOR adaptation if cerebellum is damaged

Question 82

what do lesions of cerbellum do

Answer 82

do not paralyze movement but result in large movement errors

Question 83

damage to cerebrocerebellum

Answer 83

deficits in coordination and visuomotor integration

Question 84

damage to vestibulocerebellum

Answer 84

impairs ability to stand upright and maintain direction of gaze

Question 85

damage to spinocerebellum

Answer 85

difficulty walking

Question 86

3 other signs of damage to cerebellum

Answer 86

-dysmetria -action or intention tremors -speech deficits

Question 87

dysmetria

Answer 87

over or under reaching a target

Question 88

motor + non-motor consequences of cerebellar lesions

Answer 88

chronic alcohol use can eventually degenerate the vermis -> difficulty walking (wide and staggered gait)

Question 89

movement errors are on what side of the body relative to damage to cerebellum

Answer 89

same side

Question 90

dymetria

Answer 90

movement inaccuracy

Question 91

dysdiadochokinesia

Answer 91

difficulty performing rapid alternating movements

Question 92

3 typical defects observed in cerebellar diseases

Answer 92

1. A lesion in the left cerebellar hemisphere delays the initiation of movement. The patient is told to clench both hands at the same time on a “go” signal. The left hand is clenched later than the right, as is evident in the recordings from a pressure bulb transducer squeezed by the patient. 2. A patient moving his arm from a raised position to touch the tip of his nose exhibits inaccuracy in range and direction (dysmetria) and moves his shoulder and elbow separately (decomposition of movement). Tremor increases as the finger approaches the nose. 3. A subject was asked to alternately pronate and supinate the forearm while flexing and extending at the elbow as rapidly as possible. Position traces of the hand and forearm show the normal pattern of alternating movements and the irregular pattern typical of cerebellar disorder.

Question 93

ataxia

Answer 93

difficulty producing smooth, well-coordinated movement