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Year 2: NeuroBiology > Lecture 5: Cerebellum > Flashcards

Lecture 5: Cerebellum Flashcards

1
Q

describe the structural division of the cerebellum in the transverse plane

A

3 lobes: Anterior, posterior, and flocculonodular

Primary fissure separates anterior and posterior lobe

posterolateral fissure separates posterior and flocculonodular lobes

all lobes can further be divided into lobules

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2
Q

cerebellum is the roof of what

A

4th ventricle

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3
Q

what lobe is the flocculonodular lobe

A

lobe X

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4
Q

what is a chiari malformaiton

A

defective development of cerebellum

herniation of cerebellim through foramen magnum

4 types with increasing severity and decreasing prevalence

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5
Q

type 1 chiari malformation

A

herniation of uvula and tonsil (components of cerebellum) through foramen magnum

CSF is NOT blocked

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6
Q

type 2 chiari malformation

A

herniation with myelomeningocele (type of spina bifida)

aka arnold chiari malformaiton

cyst?

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7
Q

type 3 chiari malformation

A

herniation of uvula and tonsil plus medulla (brainstem herniates too)

encephalocele (sac like protrusion around brainstem area from herniation)

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8
Q

type 4 chiari malformation

A

cerebellar hypoplasia (incomplete development)

most serious type

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9
Q

describe the functional division of the cerebellum in the sagittal plane

A

functions of the cerebellum are coordinated to the afferent CNS structures

divided into 3 components:
-spinocerebellum (middle/overlap of afferent from other 2 divisions)

-cerebrocerebellum (either side of spinocerebellum)

-vistibulocerebellum (where flocculonodular lobe is; not in sagittal division)

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10
Q

what are the 2 subcomponents of the spinocerebellum and their functions

A

vermis: important for posture and proximal extremity control; overlaps with vestibulocerebellum slightly

medial cerebellar hemisphere: important for distal extremity control

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11
Q

what is the lateral cerebellar hemisphere

A

subcomponent of the cerebrocerebellum

crosses laterally and has integrative function s

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12
Q

where is the fastigual nucleus and what is its function

A

in the vermis

balance and equilibrium

**some overlap of function with interposed nuclei and dentate nucleus

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13
Q

where is the interposed nucli and what are their functions

A

medial hemisphere of cerebellum (next to vermis)

extremity gross movement

2 components: emboliform nuclei anteriorly and globose nuclei posteriorly

**some overlap of function with fastigual nucleus and dentate nucleus

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14
Q

what is the dentate nucleus responsible for

A

integrative functions

**some overlap of function with fastigual nucleus and interposed nuclei

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15
Q

which nuclei of the cerebellum are in the spinocerebellum portion vs the cerebrocerebellum portion

A

fastigual and interposed are both in the spinal cerebellum

dentate nucleus is in the cerebrocerebellum

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16
Q

what is the vestibulocerebellum and its functional components

A

made up of flocculonodular lobe; most primitive functional component

projects directly to vestibular nuclei and fastigial nucleus

functional components:
-nodulus: vestibular function by the MLF (descending)
-flocculus: eye movement by MLF (ascending)

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17
Q

what is the inferior cerebellar peduncle/function

A

pathway that carries afferent and efferent signals

most complicated of the peduncles

acts as a conduit between spinal cord/brain stem/cerebellum

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18
Q

what is the middle cerebellar peduncle

A

carries afferent signals TO the cerebellum

Site of corticopontine decussation

-directly from pontine nuclei
-indirectly from neocortex

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19
Q

what is the superior cerebellar peduncle

A

carries efferent and afferent signals

decussation @ midbrain

efferent TO contralateral thalamus and midbrain (signals out of cerebellum)

afferent FROM spinal cord and brainstem

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20
Q

what artery supplies the anterior and superior posterior lobe of the cerebellum

A

superior cerebellar artery

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21
Q

what artery supplies the middle/inferior portions of the posterior lobe of the cerebellum

A

anterior inferior cerebellar artery (AICA)

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22
Q

what artery supplies the inferior posterior lobe of the cerebellum

A

posterior inferior cerebellar artery (PICA)

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23
Q

what does arbor vitae mean

A

tree of life

cerebellum is the tree of life

gray matter as the leaves, white matter as branches/trunk

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24
Q

what are the components of the “tree of life” of the cerebellum

A

Folium = leaf like basic structural unit

folia = multiple folium

lobule = multiple folia with obvious separating fissures

10 lobules total; #7 is the biggest

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25
Q

what are the 3 layers of the cerebellar cortex (cryoartchitecture)

A

molecular = superficial

purkinje cell layer

granular layer = deep

26
Q

what 2 types of cells can be found in the molecular layer of the cerebellar cortex and what do they synapse with

A

stellate cells: axons synapse with purkinje dendritic tree

basket cells: axons synapse with purkinje soma like a basket

27
Q

describe the purkinje layer of the cerebellar cortex

A

between other 2 layers

has a central neuron for cerebellar functions (compare to pyramid cells)

only neurons with efferent axons from the cerebellar cortex

dendritic tree is located in the sagittal plane, perpendicular to the transverse plane and the way the lobules run

28
Q

what 2 cell types can be found in the granular layer of the cerebellar cortex and what are their functions

A

golgi cells = inhibit granule cells, don’t act directly on purkinje cell

granule cells = most abundant neurons of the cerebellum
-axons ascend to molecular later as parallel fibers (wide span)
-synapse with purkinje dendritic tree UNMYELINATED

29
Q

what cells in the cerebellum release GABA as an inhibitory neurotransmitter

A

stellate cell

basket cell

purkinje cell: only efferent neurons of cerebellar cortex

golgi cell

30
Q

what cells in the cerebellum release glutamate or aspartate as an excitatory neurotransmitter

A

unipolar brush cell: only in vestibulocerebellum

granule cell

31
Q

how can we differentiate between different types of purkinje cells

A

biomarkers are used

all dendritic trees align in the sagittal plane matching functional divisions

32
Q

describe the climbing fibers (afferent) of the cerebellar cortex

A

all afferent fibers go to the molecular later and cerebellar nuclei directly

they come only from the contralateral interior olivary nuclei through the inferior cerebellar peduncle

relay all CNS components

use glutamate or aspartate as neurotransmitters

multiple axon terminals; each terminal synapses with multiple purkinje cells in the same sagittal plane

33
Q

describe mossy fibers (afferent) of the cerebellar cortex

A

go directly to the granular layer and the cerebellar nuclei

they synapse with granular cells to spread signals out through parallel fibers (each purkinje cell can get almost 105 synapses from parallel fibers)

signals are sent to the cerebellar cortex and spinal cord via all three cerebellar peduncles; glutamate or aspartate as neurotransmitters

34
Q

describe multilayered fibers of the cerebellar cortex

A

go to all 3 cortical layers and nuclei

afferent axons from: basal nuclei, diencephalon, RF, etc

use various neurotransmitters (excitatory and inhibitory)

modulate purkinje discharge rate directly or via interneurons

35
Q

Describe the cortical inhibitory loop

A

climbing fibers activate the dendritic tree of purkinje fibers

mossy fibers activate purkinje fibers via granule cells and parallel fibers

once purkinje cells are activated they release GABA and efferent fibers from the purkinje cells inhibit the cerebellar nuclei

36
Q

describe the deep excitatory loop

A

all climbing and mossy fibers project to nuclei through collateral fibers and send excitatory signals

they send signals to excite the purkinje fibers but these signals also end up travelling to the cerebellar nuclei via collateral fibers

37
Q

how often do climbing fibers fire

A

1-2x/sec

signal only from inferior olivary nucleus

synapses with dendritic tree of purkinje cells

shown as a complex spike

38
Q

how often do mossy fibers fire

A

30-100x/sec

synapse with granule cells

granule cells activate target cells via parallel fibers

shown as a simple spike

39
Q

describe what happens with mossy/climbing fibers during neuroplasticity or “learning a new trick”

A

climbing fibers modulate activities of mossy fibers

spatiotemporal summation

40
Q

describe the direct pathway of communication for motor function via the vestibulocerebellum

A

purkinje cells project to vestibular nuclei directly via the lateral vestibulospinal tract (a continuous part of the descending limb of medial longitudinal fasciculus)

signals go to the trunk/SC/proximal limbs

41
Q

describe the indirect pathway of communication for motor function via the vestibulocerebellum

A

purkinje cells project to the fastigial nuclei

Then they can go 1 of 4 different paths:
- provide bilateral signals via the MEDIAL vestibularspinal tract which mainly controls neck movement

-travel up the ascending limb of the MLF which controls eye movement

-directly project to SC (not much known about this path)

-project to contralateral thalamic nucleus VL and then to M1 for motor control

42
Q

what is the overall function of the vestibulocerebellum

A

ascending limb of medial tract = eye movement

others = postural control/balance

43
Q

what happens if there is damage to the medial longitudinal fasciculus portion of the vestibulocerebellum

A

function = to coordinate eye movement (CN III, IV, and VI)

impairment = loss of smooth pursuit (saccades), nystagmus, and diplopia

44
Q

what happens if there is damage to the vestibulospinal tract of the vestibular cerebellum

A

loss of vestibular function/postural control

truncal ataxia or titubation (truncal tremor)

45
Q

describe the cerebellar corticonuclear pathway for motor function

A

afferent signals mainly from SC and inferior olivary nucleus

signals go to the vermis of the cerebellum and the medial cerebellar cortex via the fastigial nucleus and the interposed nucleus respectively

from the nuclei, signals can travel via the superior cerebellar peduncle or the inferior cerebellar peduncle

inferior cerebellar peduncle goes directly to SC

superior cerebellar peduncle decussates in midbrain, projects to red nucleus, sends out motor control signals via the rubrospinal tract, projects to contralateral thalamic VL and then finally to the M1

46
Q

motor function of the spinocerebellum

A

position and movement of the proximal joints of the extremities and fine motor control

47
Q

describe how the cerebellar corticonuclear fiber pathway controls motor function of the cerebrocerebellum

A
48
Q

how is the cerebrocerebellum formed/motor functions executed

A

cerebral pontine tracts descending into pons

synapse with pontine nuclei

axons from nuclei cross over pons to contralateral cerebellar lateral hemisphere

cerebellar cortex projects to dentate nucleus

then projects out from the superior cerebellar peduncle

crosses over in midbrain

projects to contralateral side of the thalamus

signal is then sent to M1, premotor, supplementary motor areas, etc

49
Q

motor functions of the cerebrocerebellum

A

motor planning

initial activation of primary motor cortex

timing of muscle contraction

precise dextrous

movements of extremities

50
Q

impairments and functional loss related to damage to spinocerebellum and/or cerebrocerebellum x9

A

deterioration of coordination - decomposition of movement/dyssynergia

dysarthria (cant speak/swallow)

decrease in muscle tone (hypotonia)

decrease in DTR (areflexia)

ataxia (unsteady gait of LE)

dysmetria (hyper = overshoot, hypo = under)

intention/essential tremor (tremor with movement only)

dysdiadochokinesia (cant do quick pronation/supination)

nystagmus (b/c cerebellar projections to frontal eye field)

51
Q

describe the somatotopy o fthe cerebellum

A

redundant

anterior lobe = inverted

posterior lobe = separated (back to back on either side of vermis)

52
Q

why would a pt have more complicated S&S with an injury to the cerebellum

A

fractured representation of somatotopy- chimeric

lost somatotopy presentation in the cerebropontine tract

representation of the hand/arm are not in precise locations of the picture of the hand/arm on the somatotopy

53
Q

describe visceral motor function of the cerebellum and how a stroke may affect this

A

hypothalamus projects to cerebellum through multilayered fibers

hypothalamus controls ANS: initiate drives, fight or flight, rest/digest, etc and controls basic vitals

stroke of cerebellum can cause visceral/sympathetic motor symptoms related to somatic motor actions

54
Q

explain the example of visceral motor components associated with a stroke of the cerebellum (i.e. L SCA stroke)

A

L SCA stroke affects cerebellum

somatic motor functions impaired (i.e. L intention tremor when moving hand)

somatic motor impairements may be accompanied by visceral motor functional impairements as well (i.e. dilation of L pupil, flush of L face, etc)

symptoms stop when movement stops

S&S are related to activated sympathetic motor

injury to the fastigial nucleus from the stroke causes activation of parasympathetic n and thus combined somatic and visceral symptoms

55
Q

what sort of emotional involvement can be affected by trouble with the cerebellum/limbic system

A

emotion related to fastigual nucleus or medial region; emotions mainly encoded around vermis

trouble with emotion initiation; get mad for no reason

cant recognize via facial expressions the emotions of others

lack of social cognition- behave/accept behaviors of others; no fighting because we as humans don’t want to be isolated from one another naturally

56
Q

What might you see in a PET scan of the cerebellum in regards to language and speech

A

PET - which part of brain is activated

cerebellum activated with language

R cerebellum works more with speech

57
Q

describe the path of the viral vector when injected into brocas area

A

viral vector injected in brocas

follows axons to thalamus VL/VA

continue to dentate nucleus of cerebellum

continues to cerebellar cortex

goes down to to pontine nuclei via mossy fibers

follows down corticopontine tract

58
Q

how does the viral vector tracing prove the cerebellums function in cognition

A

broca’s area was directly linked to lobule 7 between the motor functional regions

59
Q

what functions of the CNS does the cerebellum involve

A

all

psychomotor- all motions require cerebellar input
-equilibrium
-balance
-stability
-gross limb movement
-fine distal movement

cognition

affect

60
Q
A

Year 2: NeuroBiology (10 decks)

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