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Functional Neuroanatomy > Task 3 > Flashcards

Task 3 Flashcards

1
Q

The main function of the cerebellum

A

is to detect “motor errors” between an intended movement and the actual movement and reduce this error

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2
Q

Organization of cerebellum

A

Cerevrocerebellum
Spinocerebellum
Vestibulocerebellum

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3
Q

Cerebrocerebellum

lateral hemispheres

A

occupies latreal hemispjeres, receives input from many cortex areas

Regulates highly skilled movement (planning and execution of spatial and temporal sequences)

Planning of movement and
sensory feedback of motor
movements
- Coordination of voluntary
movements
- Cognitive, emotional control
-regulatiomn of highly skilled movement (planning& execution of complex temporarl& spatial sequences)
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4
Q

Spinocerebellum (Vermis)

A

only one that receives direct input from spinal cord

lateral part/ Paramedian zone : movement of distal muscles
Vermis ( median): movement of proximal muscles and eye movements

Regulates body and limb
movements and muscle
tone

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5
Q

Vestibulocerebellum(Flocular lobe)

A

It receives input from the vestibular nuclei and is concerned with the regulation of movements underlying posture and balance
Regulates balance, posture,
eye movements+ vestibulo+ occular reflex

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6
Q

Cerebellar peduncles

A

connections between the cerebellum and other parts of the nervous system

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7
Q

transverse pontine fibers.

A

The axons in the pontine nuclei are called

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8
Q

Superior cerebellar peduncle

A

efferent pathway from the deep cerebellar nuclei to the upper motor neurons in the superior colliculus and relay in the dorsal thalamus to finally terminate in M1 and pre-motor areas

Deep cerebelar nuclei => dorsal thalamus=> premotor& primary motor areas
Deep creberar nuclei=> superior colliculus

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9
Q

Middle cerebellar peduncle

A

afferent pathway to the cerebellum coming mostly from the contralateral pons (pontine nuclei), which receives input from many sources (including superior colliculus and almost all cortical areas

most areas of the cortex& superior colliculus0> cell bodies in pontine nuclei of pons =< transverse pontine fibers cross over via middle peduncle=> cerebellar cortex & deep nuclei

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10
Q

inferior cerebellar peduncle

A

smallest but most complex peduncle that contains multiple afferent and efferent pathways
afferent = axons from vestibular nuclei, spinal cord and brainstem tegmentum;
efferent = axons project to vestibular nuclei and reticular formation

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11
Q

The majority of the cerebellar input arises from

A

the primary and pre-motor cortices (frontal lobe), the primary and secondary somatic sensory cortices (anterior parietal) and the higher order visual regions (posterior parietal).

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12
Q

Cerebellum is modulated by

A

modulatory inputs from the inferior olive and the locus ceruleus in the brainstem -> nuclei participate in the learning and memory functions served by cerebellar circuitry.

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13
Q

Dentate nucleus (largest nucleus in humans

A

receives most input from cerebrocerebellum and project mostly to premotor and association cortices (planning volitional movement)

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14
Q

interposed nuclei

A

receive most input from spinocerebellum

and output to motor cortex& Brainstem

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15
Q

Vestibular nuclei

A

Receeives from Vestibular cerebeluum and projects Lower motor neurons in spinal cord & brainstem ( balance & vestibuloclar regulation)

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16
Q

Fastigal nuclei

A

receives spino cerebellum

Output: Motor cortex

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17
Q

Closed loops

A

run parallel to open loops that receive input from multiple cortical areas and funnel output back to upper motor neurons in specific regions of motor and pre-motor cortices

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18
Q

Spinocerebellar pathways

A

project to the upper motor neurons (execution of movement).

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19
Q

Fastigal nuclei (underlie vermis near the midline of cerebellum)

A

project via inferior cerebellar peduncle to nuclei of reticular formation and vestibular complex  give rise to medial tracts governing the axial and proximal limb musculature

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20
Q

Interposed nuclei

A

project via superior cerebellar peduncle to thalamic circuits that interact with motor regions in the frontal lobe concerned with volitional movements of the limbs

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21
Q

The thalamic nuclei that receive projections from dentate and interposed nuclei are segregated in 2 subdivisions

A

oral (anterior) part of the posterolateral segment and the so-called area x. Both project directly to primary motor and premotor association cortices.

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22
Q

major descending outputs that affect upper motor neurons in brainstem

A

+superior colliculus
+reticular formation
+vestibular nuclei

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23
Q

Vestibulocerebellar efferent pathways

A

project through the inferior cerebellar peduncle to the nuclei in the vestibular complex that are responsible for eye, head and neck movements

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24
Q

mossy fibers

A

 Axons from the pontine nuclei are called mossy fibers, that synapse on neurons in the deep cerebellar nuclei (=granule cells), in the granule layer of cerebellar cortex and give rise to axons called parallel fibers, which then ascend to the molecular layer of the cerebellar cortex

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25
Q

purkinje cells input

A

input from climbing fibers, which arise in the inferior olive

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26
Q

purkinje cells

A

 Huge dendrites that branch out
 receive input from heaps of parallel fibres
 Inhibitory (GABA) to cerebellar cortex
 Projections to deep cerebellar nuclei that serve to shape discharge patterns of those

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27
Q

purkinje cells Indirect input

A

 Mossy fibres come from all sorts of sources (cortex, brainstem, spinal cord) and synapse on deep cerebellar nuclei & granule cells
 Granule cells give rise to parallel fibres that synapse on purkinje cells

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28
Q

purkinje cells direct output

A

 Inferior olive  climbing fibres  purkinje cell & deep nuclei

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29
Q

stellate cells

A

on the other hand receives input from parallel fibers and provides inhibitory input to Purkinje cell dendrites

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30
Q

Timing Hypothesis

A

 Cerebellum is critical for sensorimotor learning because it generates predictions that are temporally precise
 Cortical areas select effectors while cerebellum supplies the precise timing needed for activating these effectors
 Lesions are most disruptive to highly practiced movements, which present the greatest need for precise timing
 E.g. classical conditioning example with airpuff

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31
Q

Degeneration of anterior cerebellar cortex

A

lower limb movemnet impoaired ( alcohol)

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32
Q

Cerebellar ataxia

A

jerky & imprecise movements

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33
Q

Nystagmus

A

difficulty of eyes in maintaining fixation  drift from target then jump back

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34
Q

Dysdiadochokinesia

A

difficulty performing rapid alternating movements

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35
Q

Action/intention tremors

A

over & undershooting of movements

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36
Q

cerebellum damage

A

 Impairments in highly skilled sequences of learned movements (e.g. speech or playing instrument) Generally, result in lack of coordination of ongoing movement
 Since topographically organised, movement deficits can be pretty specific
( Anterior cerebellar cortex

37
Q

show impaired cerebellar inhibition

A

 Diseases affecting cerebellar cortex

 Diseases affecting dentate nucleus

38
Q

2 inputs of purkinje cells

A

Inferior olive+ Mossy fibers

39
Q

Long-term depression

A

Climbing fibers first activate the purkinje cell, causing a large postsynaptic EPSP. Additionally, the depolarization caused by the climbing fibers (activation of voltage-gated sodium channels), other channels, voltage-gated calcium channels, are activated as well, resulting in an increase of Ca2+ in the purkinje cell.

40
Q

Afferent pathway

A

Motor cortex=> Sensory cortex => Pons=> cerebellar cortex

41
Q

efferent pathway

A

Cerebellar cortex=> Dentate nucleus => Mottor thalamus=> Motor cortex

42
Q

People with efferent ataxia show

A

impaired inhibition

43
Q

People with affarent ataxia show

A

normal inhibition

44
Q

DISRUPTION OF STATE ESTIMATION IN THE HUMAN LATERAL CEREBELLUM (MIALL) conclusions

A

Conclusion
Suggest that these results demonstrate that the cerebellum is responsible for estimating the hand position over this time interval and the TMS disrupts this state estimate.
 Cerebellum predicts the state of the motor system.
 This hypothesis can explain the loss of movement control experienced by cerebellar patients.
 Supports computational theories that the cerebellum of a predictive model of the motor system.

45
Q

Ataxia in terms of forward model

A

people with ataxia have the ability to select the right movements in the right sequences but still lack coordination
 Their forward model is not intact (it is not synchronized with the ongoing sensory signals, much like a broken clock)

46
Q

Hypermetric movements

A

= movements that extend beyond the intended target (overreaching) => damage to spinocerebellum

47
Q

The cerebellum, as opposed to other brain areas, is not only important for prediction but also for

A

sensorimotor learning (generated predictions that are temporally precise): we don’t only need to know what Is coming, but also when it is coming. This timing is provided by the cerebellum.

48
Q

Inverse model:

A

inverts the information flow of the forward model by inputting the desired goal of the movement, i.e. its desired sensory consequences, and back calculating the motor commands that would be required to achieve this.

49
Q

Climbing fibers provide a “training” signal that

A

modulates effectiveness of the mossy-parallel fiber connections with the Purkinje cell

50
Q

Inputs from local circuit neurons modulate the inhibitory activity of Purkinje cellsThe most powerful of these local inputs are inhibitory nests of synapses made with Purkinje cell bodies by

A

basket cells

51
Q

stellate cells

A

on the other hand receives input from parallel fibers and provides inhibitory input to Purkinje cell dendrites

52
Q

The molecular layer contains

A

apical dendrites of Golgi cells (have their bodies in the granular layer) and receives input from parallel fibers and provide inhibitory feedback to origin of parallel fibers

53
Q

Golgi cells form inhibitory feedback circuit that controls

A

the gain of the granule cell input to Purkinje cells

54
Q

Reduction in efficiency of parallel fiber input to Purkinje cells has the effect of

A

increasing response of neurons in deep cerebellar nuclei to afferent activity. Signals returned from cerebellum to circuits of upper motor neurons in motor cortex and brainstem are altered as a consequence of climbing fiber activation (necessary for error correction).

55
Q

Neuronal activity in the cerebellum changes continuously during the course of a movement

A
  • Purkinje cells and deep cerebellar nuclei are tonically active at rest and change their frequency of firing as movements occur. The neurons respond selectively to various aspects of movements, including relaxation or contraction of a specific muscle, etc.
56
Q
  • Purkinje cells and deep cerebellar nuclear cells recognize potential errors by
A

comparing patterns of convergent activity that are concurrently available to both cell types. The deep cerebellar nuclei then send corrective signals to the upper motor neurons in order to maintain or improve the accuracy of the movement

57
Q

efferent

A

mossy fibers

58
Q

reeffernce

A

climbing fibers

59
Q

Cerebellar preduncle/

white matter

A

(contains
fine branching nerve
fibers

60
Q

Inputs cerebellum (lecture)

A

CC=> Pons; Vestibular inputs, Inferior olive, Spinal cord

61
Q

Outputs cerebellum (lecture)

A

Purkinje cell axons (to red nucleus, thalamus, inferior

olive, and vestibular nuclei) through DCN.

62
Q

Cognition

A

Specific function unclear but engagement in speech

production/perception and emotion processing is noted.

63
Q

Learning

A

Implicit learning / procedural memory: in the
recombination matrices of the cerebellum details of
automatic motor plans are stored that are not influenced by
the explicit motor plans of the cortex.
• Associative learning: certain sensory input is automatically
combined with specific motor output (e.g. eye lid closure
reflex).

64
Q

Cerebellum disfunction

A

• Most noted are different forms of ataxia, which are

dysfunctions of motor coordination.

65
Q

Cerebellar lesion evidence reveals

A

cerebellum monitors prediction outcome (N1 suppression)
- impaired use of temporal structure in auditory deviance processing (N1,
P3b)
- impaired temporal integration of multimodal information
 evidence of generalizability of forward model across domains (see

66
Q

purkinje neurons are

A

inhibitory, thus when they slow or stop firing their targets are excited.Purkinje neurons inhibit their targets in the deep nuclei.
This “sculpting inhibition” of descending motor commands
allows cerebellum to smooth & coordinate movement.
Lesions cause ataxia, intention tremor & decomposition of
movement

67
Q

What kind of information does the cerebellum receive

A

somatosensory

  • visual
  • auditory
  • vestibular
  • proprioceptive
68
Q

motor learning in cerebellum

A

Associative forms of motor learning occur in the
cerebellum. Climbing fiber inputs instruct co-active parallel
fiber inputs to undergo long term decreases in strengt

69
Q

The Purkinje Cells

Receive

A 
Excitatory Input
From Two Afferent Fiber
Systems and Are
Inhibited by Three Local
Interneurons
70
Q

Synaptic organization of the

basic cerebellar circuit module.

A

Mossy and climbing fibers convey
output from the cerebellum via a main excitatory loop through the
deep nuclei.
This loop is modulated
by an inhibitory side-loop passing through the cerebellar cortex.

71
Q

when you tickle yourself

A

less crebellar activation becasue less error to be corrected

72
Q

when schizophrenic tickle themself

A

they have problem with prediction - - had no difference if you or another person is tickeling you- high cerebellar activation even if they tickle themself

forward model is detective

73
Q

someone else tickles you

A

activity in S2 ( somatosensory cortex) & anterior cingulate gyrus

74
Q

fast forward loop

A

Cortex=> cerebelar cortex(with modulatory inputs)=> Relay nuclei=> Thalmus=> cortex

75
Q

MEDIALPORTION OF CEREBELLAR CORTEX

A

concerned with medial parts of the body ( proximal muscles)

76
Q

lateral parts of cerebeallr cortex

A

cincerned with more distal muscles

77
Q

Cerebellum input genau

A

 From cortex via pontine to cerebrocerebellum
 Spinal cord (dorsal nucleus of Clarke) & medulla (external cuneate nucleus) => spinocerebellum
Innervated by proprioceptive( knowing where your hands are ) axons from lower & upper body parts respectively
Sensory infromation
 Trigeminal complex (mesencephalic nucleus) => spinocerebellum Proprioceptive signals from the face, teeth and jaw movements, preventing to bite down so your teeth break

Entire cerebellum receives input from inferior olives & locus coeruleus in brainstem  learning & memory function

78
Q

output cerebellum

A

 To deep cellular nuclei (4 kinds)
 Dentate nucleus (cerebrocerebellum)
 Two interposed nuclei (paramedial)
 Fastigial nucleus (vermis)

79
Q

 Cerebrocerebellar pathway (ascending)

A

– destined for pre-motor & associational cortices of frontal lobe  motor planning

80
Q

 Spinocerebellar pathways (ascending)

A

directed to upper motor neurons responsible for execution of movement
 Laterally positioned interposed nuclei project via superior peduncle to thalamus and frontal lobes

81
Q

 Vestibulocerebellar pathway (descending)

A

 Inferior peduncle  vestibular complex that governs movement of eyes, head, neck, compensating for linear & rotational accelerations of the head

82
Q

mossy fibers

A

come from all sorts of sources (cortex, brainstem, spinal cord) and synapse on deep cerebellar nuclei & granule cells
Indrirect because mossy go through through paarrale fibers

83
Q

granule cells

A

give rise to parallel fibres that synapse on purkinje cells

84
Q

direct input to purkinje cell

A

nferior olive  climbing fibres  purkinje cell & deep nuclei

85
Q

basket cells & stellate cells

A

modulate inhibitory output by purkinje cell

86
Q
  • Purkinje cells and deep cerebellar nuclear cells recognize potential errors by comparing
A

patterns of convergent activity that are concurrently available to both cell types. The deep cerebellar nuclei then send corrective signals to the upper motor neurons in order to maintain or improve the accuracy of the movement

87
Q

Marr-Albus theory of motor learning

A

specifically predicts plasticity of the parallel fiber synapse if it is active at the same time as the climbing fiber input to the postsynaptic Purkinje cell- input specificity ( both have to be at the same time)

88
Q

ascending pathways

A

Crebrocerebellum=> Denate nucleus=> Premotor cortex(Motor planning)

Spinocerebellum=> Interposed & fastigal nuclei => Motor cortex & Brainstem ( Motor execution)

Vestibulocerebellum => Vestibular nuclei=> Lower motor neurons in spianl cord & brain stem ( balance & vestibbulooccular)

Functional Neuroanatomy (5 decks)

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