Cerebellum Flashcards

1
Q

circuitopathies

A

disorders caused by the dysfunction on a single cell level

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2
Q

Where does the cerebellum get inputs from?

A

The association areas

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3
Q

Where does the cerebellum project to?

A

The ventromedial thalamus

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4
Q

is the cerebellum attached to the brain stem?

A

Yes

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5
Q

Anatomical output of the cerebellum

A

rubber nucleus –> thalamus. Exit projections are also from the vestibulocerebellum.

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6
Q

Motion information project to where in the cerebellum?

A

the cerebellar nuclei

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7
Q

Phylogenetical subdivisions of the cerebellum

A

Palaeocerebellum (spinocerebellum), Neocerebellum (Cerebrocerebellum) and Archicerebellum (Vestibulocerebellum)

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8
Q

Functional names for the cerebellar devisions

A

Spinocerebellum
Cerebrocerebellum
Vestibulocerebellum

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9
Q

Spinocerebellum

A

For movement execution. It integrates movement of the limbs and controls targeted motor function and the motion’s execution, e.g. to grip a cup or to eat a soup.

It gets somatosensory and proprioceptive inputs from the spinal cord (intermediate parts) and other sensory information (Vermis)
project through the fastigial nucleus to control proximal muscles (vermis) and the interposed nucleus to distal parts (intermediate parts).

Consists of the vermis and intermediate hemispheres

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10
Q

Cerebrocerebellum

A

Movement planning. It mediates motor learning and computes the movement (e.g. plan of to reach for something)

  • Almost all inputs to and outputs from this region are connected with the cerebral cortex.
  • Outputs go through he dentate gyrus.
  • Projects to motor (including areas 4 + 6), premotor, and prefrontal cortices
  • It’s the newest in development
  • Very connected to the motor cortex
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11
Q

Vestibulocerebellum

A

Balance and eye movement. The oldest part of the cerebellum. The flocculonodular lobe receives vestibular and visual inputs from the labyrinth and projects to the vestibular nuclei in the brain stem.

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12
Q

Vermis

A

Separates the cerebellum into 2 when we look at it from behind. Governs posture and locomotion as well as eye movement. Is the youngest part of the Spinocerebellum.

The vermis receives visual, auditory, and vestibular input as well as somatic sensory input from the head and proximal parts of the body.

As part of the spinocerebellum, it projects through the fastigial nucleus to cortical and brain stem regions (rubber nucleus, reticular formation and vestibular nucleus) to control proximal muscles of the body and limbs.

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13
Q

folia

A

The convoluted with parallel folds in the surface of the cerebellum (like the gyri/sulci)

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14
Q

The primary fissures on the dorsal surface separate the?

A

anterior/posterior lobe

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15
Q

The posterolateral fissure seperates?

A

The body of the cerebellum from the Vestibulocerebellum/flocculo-nodular lobe

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16
Q

Cortical input to the thalamus is sent to the?

A

the cerebellar nuclei

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17
Q

What do we know about the evolution of the cerebellum in animals?

A

The cerebellum is more simple (just Vestibulocerebellum/flocculo-nodular lobe activations) in a catfish than in mammals and birds. The cerebellum controls more complex programs of the movements on a higher evolutionary level (first with the Cerebrocerebellum being the last developed)

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18
Q

Symptoms of a vestibulocerebellum dysfunction

A

dysregulations of balance, the oculomotor system and the coordination of the movement of the eye, the head and the body

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19
Q

intermediate hemispheres

A

Part of the spinocerebellum but projects through the interposed nucleus, which provides inputs to the motor cortex and rubrospinal systems and controls the more distal muscles of the limbs and digits.
It gets input about somatosensory information (proprioception, touch, pain, temp) and it’s important for directed mobility.

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20
Q

Symptoms of vermis dysfunction

A

dysregulations in the posture, walk, upper and lower limbs and can cause speech impediments

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21
Q

Intermediate hemispheres projections

A

Input: somatosensory system –> cerebellar cortex –> interposed nucleus & rubber nucleus
Ouput: interposed nucleus –> thalamus –> area 4 of the motor cortex –> spinal cord
rubber nucleus also projects to the spinal cord, where in the and output is integrated

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22
Q

Output nuclei of Cerebrocerebellum?

A

dentate nucleus

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23
Q

Output nuclei of the Vermis?

A

fastigial nucleus

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24
Q

Output nuclei of the Intermediate hemispheres?

A

interposed nucleus

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25
Q

Inputs of the Cerebrocerebellum?

A

From the cerebral cortex (through the pons)

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26
Q

Projections of the Cerebrocerebellum?

A

Projects to motor (including areas 4 + 6), premotor, and prefrontal cortices, rubber nucleus and the red nucleus

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27
Q

Evolution of the cerebellum

A

Oldest: vestibulocerebellum, middle: Spinocerebellum (vermis newer than Intermidate hemispheres), newest: Cerebrocerebellum

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28
Q

Function of the Cerebrocerebellum

A

Movement planning. It mediates motor learning and computes the movement (e.g. plan of to reach for something). Might be important for other cognitive functions such as working memory working memory.

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29
Q

Function of the Spinocerebellum?

A

For movement execution. It integrates movement of the limbs and controls targeted motor function and the motion’s execution, e.g. to grip a cup or to eat a soup.

Vermis: Governs posture and locomotion as well as eye movement and for proximal limbs

Intermediate hemispheres: important for directed mobility and for distal limbs

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30
Q

Function of the vestibulocerebellum

A

Balance and eye movement.

31
Q

Cerebellar disease: Cerebellar hypotonia

A

less muscle strength and tone

32
Q

Cerebellar disease: Dysmetria

A

dysregulation of target-directed voluntary movements.

33
Q

Cerebellar disease: Hypo- or hypermetria

A

Finger to nose movement. You take your finger to target the nose. The more the finger approaches the nose the larger is the amplitude of the unvoluntary movements.

34
Q

Cerebellar disease: Scanning speech

A

is a type of ataxic dysarthria in which spoken words are broken up into separate syllables, often separated by a noticeable pause, and spoken with varying force.

35
Q

Cerebellar disease: Asynergia

A

Missing coordination of different groups of muscles.

36
Q

Cerebellar disease: Intention tremor

A

Intention tremor is a dyskinetic disorder characterized by a broad, coarse, and low frequency (below 5 Hz) tremor evident during deliberate and visually-guided movement (hence the name intention tremor). An intention tremor is usually perpendicular to the direction of movement. When experiencing an intention tremor, one often overshoots or undershoots one’s target, a condition known as dysmetria.

37
Q

Ataxia

A

Ataxia of the movement means affected coordination of different muscle groups. The agonist and the antagonist are not coordinated and the movement swings. Very typical for this is the intensiontremor. The more the patient approaches the bottle to grip it with the hand, the larger are the amplitudes of his movement.

38
Q

3 layers of the cerebellar cortex

A

molecular, purkinje and granular layers

39
Q

Cells in the molecular layer

A

stellate and basket cells (inhibitory interneurons), dendrites from the purkinje cells and paralelle firbers (axons of the granule cells)

40
Q

Cells in the purkinje layer

A

purkinje cells

41
Q

Cells in the granular layer

A

Golgi interneurons, mossy fibers, granule cells and axons of purkinje cells

42
Q

Characteristics of purkinje cells

A

largest neuron in the nervous system, gets inputs from parallel and climbing fibers, has tonic firing, is inhibitory (GABA), no resting membrane potential, Purkinje cell is orientated in the sagittal plane.

43
Q

Characteristics of granule cell

A

Cell bodies in the granule layer, 100 billion cells, axons form parallel fibers in the molecular layer, where they synapse onto purkinje cells and release glutamate. Here the convergence is VERY high (200K-1 mio: 1)

44
Q

Function of mossy fibers

A

Afferent input to the cerebellum.
Cell-bodies in the spinal cord and brainstem. Sends somatosensory information to the spinocerebellum, information from the balance organ and vestibule nuclei to the vestibulocerebellum and motor information to the Cerebrocerebellum.

45
Q

mossy fiber/granule cell synapse

A

Mossy fibers project to granule cells in an excitatory manner. A few mossy fibers project to the granule cells. The synapses are called glomeruli. They form many synaptic sides per cell and therefore efficiently transmit information.
The synapse is large and Mossy fibers can create 1000 APs per sec.

46
Q

The en passant synapse

A

Between the granule and purkinje. The en passant synapse is 200-300 nm in size, which anatomically is very different to the glomeruli synapse. The parallel fibers produce brief, small excitatory potentials in Purkinje neurons. Many parallel fibers are needed to have a substantial effect on the frequency of simple spikes (tonic firing)

47
Q

Simple spikes

A

Tonic firing of the Purkinje cells. This increase with movement, likely due to mossy fiber signaling (Mossy fibers control the simple spikes)

48
Q

Characteristics of climbing fibers

A

Cell body in the interior olivary nucleus
Conveys sensory information
Wraps itself around dendrites of Purkinje cells (divergence 1-10:1)
Has powerful influence on Purkinje cells as one AP causes a long depolarization of Purkinje cells –> it reflects an event and frequency of firing is therefore not relevant
The firing of multiple climbing fibers as once signal important event

49
Q

The 3 interneurons in the cerebellum

A

Basket cells and stellate cells are inhibitory neurons in the molecular layer. Golgi cells are inhibitory neurons in the granular layer and have a regulatory function at the mossy fiber synapses at the glomeruli.

50
Q

Who binds onto who?

Purkinje cell, mossy fiber, granule cells

A

mossy fibers —- glomeruli —> granule cells

granule cells —- en passant synapse —> Purkinje cell

51
Q

Stellate cell signalling

A

Are excited by parallel fibers from the granule cells and inhibit the Purkinje cells (note that the Purkinje cells also are activated by the parallel fibers)

52
Q

Basket cells signalling

A

Inhibit the Purkinje cells on the soma

53
Q

What does Purkinje firing really mean?

A

It’s an inhibitory signal to the deep cerebellar nuclei (the only inhibitory firing). The Purkinje cells has to integrate a lot of inhibitory and excitatory information, as they fire when the sensory feedback does not match that of the movement plan (prediction error in the inverse model).

54
Q

Which cells in the cerebellum projects to the deep cerebellar nuclei?

A

The Purkinje cells, the mossy fiber and the climbing fibers

55
Q

The deep cerebellar nuclei can inhibit which midbrain nucleus?

A

The inferior olivary nucleus, where the cell bodies of the climbing fibers are based

56
Q

Another term for the molecular layer?

A

the Bergmann glia

57
Q

Cranule cells in development

A

Are placed in the external granular layer (outside the molecular layer) and will migrate to the internal granular layer (what we know as the granular layer) over time.
The structure of the cerebellum is not before maturation is complete in early adulthood.

58
Q

Primary cause of cerebellar dysfunction?

A

Loss of Purkinje cells

59
Q

How does alcohol affect cerebellar based movement?

A

Leads to atactic movements, problems in walking and balancing, slurred speech

60
Q

What change in Purkinje cells leads to hypertherima?

A

An increased sensibility against higher body temperatures

61
Q

Dysdiadochokinesis

A

Impairment of fast sequence of antagonistic movements.

62
Q

Gait ataxias are characterized and cause by by?

A

Symptoms are: missing coordination of the eye and the hands as well as uncoordinated speech
Cause: Atrophy of the cerebellum

63
Q

What is most common: dominant or recessive ataxia?

A

Dominant

64
Q

Most common recessive ataxia?

A

Friedreich’s Ataxia

65
Q

The autosomal dominant forms the spinocerebellar ataxias are mostly cause by what?

A

nucleotide repeat disorders of CAG repeats

66
Q

Treatment of Ataxias

A

Physiotherapy (to help coordination), no alcohol (if it’s alcohol induced), vitamin E
Drugs: Carbamazepin, Acetazolamid, 4-Aminopyridin

67
Q

In addition to Friedreich‘s ataxia, what are other repeat diseases?

A

Fragile X syndrome & Myotonic dystrophy

68
Q

weaver mutant mouse model

A

the granule cells die after differentiation, as well the Purkinje cells show an affected maturation (mutation in a K+-channel).

69
Q

staggerer mutant mouse model

A

most of the Purkinje cells are missing; mutation in the retinoic-acid-related-orphan-receptor.

70
Q

nervous mutant mouse model

A

degeneration of Purkinje cells after maturation of synaptic connections

71
Q

reeler mutant mouse model

A

affected migration of Purkinje cells due to mutation in the ECM protein Reelin). The number of granule cells are also reduced.

72
Q

The cerebellum is important in what type of learning?

A

classical conditioning (non-declarative memory)

73
Q

How does cerebellum relate to adaptation?

A

The cerebellum can help us adabt when our visual information is distorted (magnified, skeewed, becomes smaller) and make the movement fit according to the new input. If the distortions are removed, it will take a while to get back to baseline. Patients with a damaged cerebellar cortex or inferior olive can’t adapt though.