The Cerebellum and Motor Learning Flashcards
(49 cards)
1
Q
Cerebellum: Function:
A
- receives sensory info
- influences motor function
- involved in motor learning and higher
function - not involved in interpretation or
discrimination - does not initiate movement
2
Q
Cerebellar Anatomy:
A
insert
3
Q
Label the diagram below.
A
insert diagram
4
Q
Three lobes of the cerebellum are
A
- anterior
- posterior
- flocculonodular
5
Q
The two hemispheres of the cerebellum are connected in the midline by the
A
vermis
6
Q
Functional organisation of the cerebellum:
A
insert diagram
7
Q
Internal structure of the Cerebellum:
A
- outer layer is the cerebellar cortex
- white matter tracts
- deep cerebellar nuclei:
- fastigial nucleus medially
- dentate nucleus laterally
- interposed nucleus in between the
globose and emboliform nucli
8
Q
Cerebellar Afferents travel
A
- directly from the spinal cord
- via the brainstem nuclei
9
Q
All input into the cerebellum is
A
excitatory
10
Q
Afferent pathway to the cerebellum:
A
- sensory information from muscle
spindles or golgi tendon organs in
skeletal muscle travels to the cerebellum
through - direct ipsilateral pathways (dorsal
spinocerebellar, cuneocerebellar and
ventral spinocerebellar - synapses with brainstem nuclei (inferior
olivary nuclei) and passes over to the
contralateral cerebellar cortex cia the
inferior peduncle
11
Q
Three direct ipsilateral pathways for sensory information from the muscle cells to cerebellum:
A
- dorsal spinocerebellar tract: info on
individual muscles of legs - cuneocerebellar tract: info on individual
muscles of arms - ventral spinocerebellar tracts: whole
limb, synergy of movement
12
Q
Vestibular nuclei relays info from
A
the vestibular system to the cerebellum
13
Q
Reticular Formation Nucleus: Function:
A
modulating spinal reflexes acting on extensors
14
Q
Red Nucleus: Function:
A
relays info from cerebral cortex to cerebellum via the inferior olivary nucleus
15
Q
Inferior Olivary Nucleus: Function:
A
integrates signals from spinal cord and the cerebral cortex
16
Q
Deep Pontine Nuclei: Function:
A
fibers from all regions of the cerebral cortex synapse with deep pontine nuclei to connect to the contralateral cerebellum via transverse fibers
17
Q
Tectum Nuclei: Function:
A
fibers from inferior and superior colliculus provide auditory and visual input to the cerebellum via deep pontine nuclei
18
Q
Cerebellar Output
A
insert diagram
19
Q
Functional part: Vestibulocerebellum:
A
- involved in balance/eye movement
- input from vestibular nuclei to the
folocculonodular lobe - output via vestibular nuclei and co-
ordinates with visual cortex, superior
colliculus and reticular formation nuclei
20
Q
Vestibulocerebellum:
A
insert diagram
21
Q
Functional Part: Spinocerebellum:
A
- vermal and paravermal cortex
- inputs from spinocerebellar tracts and
brainstem nuclei - vermis: output via fastigial nucleus and
medial descending tracts affecting
motor execution - paravermis:
- output via interposed nuclei and
lateral descending tracts affecting
motor execution
- output via inferior olivary nucleus to
red nucleus and cerebral cortex for
motor control and learning
22
Q
Spinocerebellum:
A
insert diagram
23
Q
Functional Part: Pontocerebellum/Cererbrocerebellum:
A
- remaining lateral part, largest volume
- main input via deep pontine nuclei,
giving rise to transverse pontin fibers
that enter cerebellum by contralateral
middle cerebellar pepduncle - output via dentate nucleus
- role in motor planning, control etc
- role in cognition, speech, behaviour
24
Q
All output from the cerebellum to the deep cerebellar nuclei is ———-
A
inhibitory
25
All output from the deep cerebellar nuclei is
excitatory
26
All messages from the cerebellum are coded by
excitation and inhibition
27
What are the two main types of fibers that input into the cerebellum?
- mossy fibers
- climbing fibers
28
Cerebellar Cortex: 3 Layers:
- molecular layer
- purkinje cell layer: output from the
cerebellar cortex to deep nuclei
(inhibitory)
- granule cell layer (outermost layer)
29
Output from the cerebellum occurs via the (2):
deep cerebellar nuclei or vestibular nuclei
30
Somatotopic Representation of the cerebellum:
area on the body that corresponds to a particular part of the nervous system
31
Cerebellum: Granular Layer: Cell Types:
- mainly granule cells (dendrites receive
mossy fiber afferents)
- golgi cell dendrites contact terminals of
mossy fibers and dendrites of granule
cells in cerebellar glomerulus
32
Granular Layer:
insert diagram
33
Granule Cells:
- in granule layer
- 3-5 dendrites from granule cell receive
mossy fiber afferents
- axon ascends to cortex surface
- bifurcates in molecular layer
- parallel fibers contact the purkinje cell
dendrites and excite the purkinje cells
34
Golgi cells:
- granular layer
- inhibitory GABA-ergic
- receives afferents from parallel fibers
and from mossy fibers
- contacts dendrites of granule cells and
terminals of mossy fibers
35
Cerebellar: Purkinje Cell Layer:
- contains purkinje cell
- one cell layer thick
- thick dendrites project to the molecular
layer
- axon descends to deep cerebellar nuclei
or vestibular nuclei
- output is inhibitory
36
Cerebellar Cortex: Molecular Layer:
- dendrites of purkinje cells
- terminal branches of climbing fibers
- parallel fibers of granule cells
- 2 types of interneurons: basket cells and
stellate cells, which make inhibitory
contact with purkinje cells to sharpen
the focus
37
Climbing Fibers:
- from inferior olivary nucleus
- branches may synapse with deep
cerebellar nucleus (stimulatory)
- ascends to molecular layer of cerebellar
cortex
- synapses with dendrites of one purkinje
cell
- one climbing fiber to one purkinje cell,
purkinje cell output is inhibitory
38
Mossy Fibers:
- branches in granular layer can directly
stimulate deep cerebellar nucleus
- end in mossy fiber rosettes, held by
dendrites of granule cells
- granule cells then influence purkinje
cells through parallel fibers
- also contact golgi cell dendrites
39
Action of mossy fibers and climbing fibers on purkinje cells lead to
motor learning
40
Synaptic plasticity of purkinje cells in cerebellum initiated by
the repetition of an action
41
Symptoms affecting movement and tone are less likely to cause symptoms if dysfunction is in
the cerebellar cortex
42
Cerebellar dysfunction symptoms are worse if what structure if affected?
the cerebellar nuclei
43
If the paravermal cerebellar hemisphere is affected what symptoms would be seen?
affects ipsilateral function (connections via interposed nuclei or dentate nuclei)
44
If the cerebellar vermis is affected what symptoms would be seen?
affects trunk, axxial muscles and eye movements
45
Cerebellar Dysfunction: Symptoms:
- uncoordinated movements
- tremor
- unsteadiness
- oscillopsia
- slurring of speech
46
Cerebellar Dysfunction: Signs:
- finger nose incoordination
- dysdiadokokinesia
- heel shin incoordination
- gait ataxia
- hypotonia
- nystagmus
- staccato speech
47
A space occupying lesion or vascular lesion in one hemisphere of the cerebellar dysfunction.
Symptoms and signs?
- ipsilateral past pointing, dysdiadokinesia
- intention tremor
- lateral hemisphere projects via dentate
nucleus to cerebral cortex via thalamus
- feedback to motor cortex disrupted
- affects intentional movements
48
Alcoholic Cerebellar Degeneration:
- affects
- symptoms
- signs
- affects midline anterior vermis and
paravermis
- legs>arms incoordination
- truncal ataxia most marked
- nutritional deficiency leads to
degeneration of purkinje cells more
marked in regions discussed
- axial muscles represented more
medially, close to vermis
- legs represented in the anterior
paravermal region
49
Medulloblastoma affecting the fastigial nucleus and vermis symptoms and signs?
- truncal ataxia due to midline vermis
involvement
- nystagmus as connections via fastigial
and vestibular nuclei
