Week 6 Learning Issues Part 2 Flashcards
1
Q
Grey matter components of mature cerebellum
A
cerebellar cortex and cerebellar nuclei
2
Q
cerebellar cortex organizatoin
A
similar to cerebral cortex; neuron cell bodies have migrated to surface and white matter is deep to grey matter
3
Q
folia
A
narrow ridges which cover surface of cerebellar cortex increasing surface area
4
Q
cerebellar white matter
A
- deep to cerebellar cortex
- contains axons traveling to and from cerebellar cortex
- cerebellar nuclei embedded in white matter
5
Q
cerebellar cortex regions
A
- medial region= vermis
- 2 lateral regions= hemispheres
6
Q
medial regions of hemispheres
A
paravermis and vermis; paravermis lateral to vermis(fnxly not anatomically distinct from lateral region of hemisphere)
7
Q
cerebellum lobes
A
- 3 transversely oriented lobes
- floccularnodular lobe
- rostral lobe
- cd lobe
8
Q
floccularnodular lobe
A
- most cd lobe
- most primitive pt of cerebellum
- tucked under cd aspect of cerebellum overlying medulla
- closely associated with vestibular system
9
Q
floccularnodular lobe parts
A
- midline modulus
- lateral flocculus
10
Q
vestibular nuclei and flocculonodular lobe
A
in rostral medulla just ventral to flocculonodular lobe
11
Q
primary fissure
A
separates rostral and cd lobes
12
Q
rostal lobe
A
plays important role in posture and muscle tone
13
Q
histological layers of cerebellar cortex
A
- molecular layer (most superficial)
- Purkinje cell layer
- granule cell layer (deepest)
14
Q
molecular layer
A
most superficial and contains:
- axons of granule cells, -dendrites of purkinje cells,
- sparsely distributed interneurons
15
Q
Purkinje cell layer
A
- contains single row large neurons
- sends dendrites into molecular layer and an axon into white matter to synapse on cerebellar nuclei
16
Q
granule cell layer
A
- deepest cortical layer
- relatively small, densely packed neurons
- interneurons connecting these neuron populations
17
Q
different neuron types of cerebellar cortex are interconnected
A
in specific pattern that is same in all regions of cerebellum allowing cerebellum to process afferent information and generate an output that sculpts activity in motor pathways
18
Q
cerebellum fx
A
- must analyze sensory and motor information to produce useful regulation of motor fx
- sensory and motor info from all regions of CNS must get to cerebellum
19
Q
how does cerebellum regulate motor fx
A
by projecting to UMNs in the motor cortex and brainstem
20
Q
cerebellar representation
A
ipsilateral
21
Q
sensory pathways carrying for fro spinal cord
A
either don’t cross or cross twice
22
Q
cd cerebellar peduncle
A
dorsal spino- and cuneo-cerebellar pathways send proprioceptive info to cerebellum via cd cerebellar peduncle
23
Q
information relayed to cerebellum
A
- proprioceptive information
- highly processed sensory information from visual, somatosensory, and auditory cortex
24
Q
information traveling from forebrain to cerebellum
A
must decussate b/c forebrain contains contralateral representation
25
forebrain to cerebellum pathway
- cerebral cortex
- synapse on pontine nuclei
- axons of these neurons decussate in transverse fibers of the pons
- middle cerebellar peduncle
- cerebellum
26
cerebellum to forebrain pathway
- cerebellum
- rostral cerebellar peduncle
- decussate in midbrain
- forebrain
27
afferents to cerebellum synapse in
cerebellar nuclei and cerebellar cortex
28
information in cerebellum is processed in
cerebellar cortex
29
output of the cerebellar cortex
-purkinje cell which projects to cerebellar nuclei
30
purkinje cell output
- projects to cerebellar nuclei
- has inhibitory effect on cerebellar nuclei, thought to sculpt outflow from cerebellum to provide appropriate signals to motor systems
31
each cerebellar nuclei receive input from
- a specific region of cerebellar cortex
32
lateral hemisphere purkinje cells project to
dentate nucleus -> motor cortex (movement planning)
33
paravermis purkinje cells project to
interpositions nucleus -> lateral motor pathways (movement execution)
34
vermis purkinje cells project to
fastigial nucleus -> medial motor pathways (movement execution)
35
output from flocculonodular lobe goes
directly to vestibular nuclei (balance and eye movements)
36
cerebellar nuclei provide
output for the cerebellum
37
cerebellar nuclei control
-fx in motor systems by synapsing on UMNs that give rise to various motor pathways
38
major target of cerebellar output
is UMNs of motor pathway
39
functional divisions of motor processing
- vestibulocerebellum
- spinocerebellum
- cerebrocerebellum
- these regions not significantly interconnected; operate as independent systems to regulate different fxs of motor pathways
40
vestibulocerebellum
- flocculonodular lobe
| - role in vestibular fx
41
spinocerebellum includes
- vermis and paravermis, fastigial and iinterpositus nuclei
42
spinocerbellum fx
- involved in modifying ongoing movements to compensate for errors detected by sensory feedback
43
cerebrocerebellum includes
lateral hemispheres and dentate nuclei
44
cerebrocerebellum involved in
planning, initiating, and coordinating movements
45
Forms of ataxia
- cerebellar ataxia
- general proprioceptive ataxia
- vestibular ataxia
46
cerebellar ataxia is
lack of coordination that can occur due to cerebellar lesions
47
characteristics of cerebellar ataxia
- depend on what region of cerebellum is affected
- hypermetria (w/ excessive flexion of limbs)
- wide based stance
- unsteady gait
- intention tremors
- side to side or front to back swaying of the trunk
- loss of balance and decomposition of limbs
48
General proprioceptive ataxia in all 4 limbs caused by
- lesions of brainstem and C1-C5
- ataxia is due to interruption of general proprioceptive pathways to brainstem, to the cerebral cortex and to cerebellum
49
General proprioceptive ataxia characterized by
- crossing over of limbs
- scuffing
- interference
- gait over-reaching
- limbs extended and advanced for prolonged duration during protraction fo limb (floating/ overreaching)
50
gait abnormalities seen with medullary and C1-C5 lesions are
a combination of ataxia and spastic tetraparesis
51
spastic tetraparesis seen with medullary and C1-C5 lesions due to
interruption of descending UMN pathways
52
vestibular ataxia characterized by
- imbalance
- circling
- turning and/ or falling over
53
pure vestibular ataxia
- occurs with peripheral vestibular dx
- animal will maintain ability to quickly move feet and place them appropriately to avoid falling down will be maintained; these animals will have short choppy strides and wide based stance
54
vestibular lesions in medulla
vestibular ataxia will be complicated by general proprioceptive ataxia and spastic paresis and signs of all 3 of these deficits will be evident to varying degrees
55
cerebellar lesions can
result in vestibular ataxia which will likely be seen in conjunction with cerebellar ataxia (which can include hypermetria, truncal tremors, and intention tremors, and other deficits localizable to cerebellum)
56
animals with cerebellar lesions will not
be paretic or plegic because cerebellum does not contain UMNs and does not contribute to general strength of movement
57
decerebellate rigidity caused by
- caused by large lesions of cerebellum especially those affecting rostral lobe
58
decerebellate rigidity characterized by
- extension of forelimbs, opisthotonus, and often flexion of hips
- if lesion confounded to cerebellum, patient will be conscious and aware of sensory stimulation (THIS IS DIFFERENT THAN DECEREBRATE RIGIDITY)
59
Cerebellar hypoplasia
- affects kittens and calves with mothers affected by panleukopenia virus (kittens) and BVD (calves) while pregnant; if infection occurs during rapid cell proliferation in granule cell layer of cerebellar cortex cells become infected by virus and die (other types cells in cerebellum may also be affected); cats can live with this condition
60
cerebellar cortical abiotrophy
seen in dogs, cats, horses (Arabians), cattle, possibly sheep and pigs; degeneration of certain cell populations (especially purkinje cells) w/ in cerebellar cortex due to premature cell death; occurs early in life animals normal at birth then progress in severity
61
cerebellar fxs
1. Motor planning and initiation
2. Adjust ongoing motor programs to compensate for unanticipated errors
3. Coordinate timing and pattern of muscle contractions
4. Regulate muscle tone, posture and vestibular reflexes
5. Plays important role in long term motor learning
62
motor planning and initation
Cerebrocerebellum
63
adjust ongoing motor programs to compensate for unanticipated errors
- Spinocerebellum
- cerebellum receives input about intended movement from UMNs to various motor pathways and sensory info (feedback) related to ongoing movement then influences activity in UMNs of various motor pathways to make necessary corrections in motor program
64
coordinating timing and pattern of muscle contractions
to keep movements smooth and continuous
65
regulates muscle tone, posture, and vestibular reflexes
vestibulocerebellum
66
example of cerebellum playing an important role in long term motor learning
VOR; signals to LMNs involved in eye movements to accomplish VOR depend on factors including distance between eyes and location in head so cerebellum makes adjustments needed to keep VOR accurate as head moves
- cerebellum also important for learning conditioned responses
67
basal ganglia and cerebellum process
diverse info regarding sensory feedback, reward and punishment, memory, motivation, arousal, and ongoing motor commands, and influence motor output by regulating UMNs
68
basal ganglia are involved in
aspects of motor coordination and planning
69
cerebellum involve in
coordinating execution of ongoing movements so they are smooth and accurate
70
basal ganglia
- subset telencehalic basal nuclei
- substantia nigra
- subthalmic nucleus
71
substantia nigra location
in ventral midbrain
72
subthalmic nucleus
in diencephalon
73
subset telencephalon basal nuclei involved in
motor coordination and control
74
group of nuclei of basal ganglia form
several parallel loops that connect many areas of neocortex w/ UMNs in motor cortex with brainstem motor nuclei
75
loops can
process diverse info from cortical and subcortical systems and regulate activity of UMNs
76
basal ganglia involved in
motor planning, initiation and termination of movements, oculomotor control, play role in influencing higher cognitive and limbic fxs
77
Equine Nigropallidal Encephalomalacia
seen in horses that eat yellow star thistle or Russian knapwood affects basal ganglia (in substantia nigra and globes pallid us) -> motor dysfunction associated with facial muscles -> starvation -> death
78
lesions of cerebellum clinical signs
- ataxia (lack of coordination bc cerebellar lesion bc not coordinating motor coordination if cerebellum can't fx properly)
- intention tremors (spinocerebellum?)
- exaggerated movements (hypermetria) (cerebrocerebellum?)
- vestibular dysfunction (vestibulocerebellum)
79
structural and vascular lesions affecting basal ganglia and adjacent subcortical structures can cause
circling behavior and neglect similar to those seen with forebrain lesion
80
forebrain lesions tend to cause
- wide circles or driving movements toward side of lesion
- neglect of stimuli contralateral to the lesion
- mental dullness
- behavioral changes
- +/- seizures
- +/- contralateral menace deficits, postural rxn deficits, and decreased sensation of noxious stimuli
81
neglect occurs
bc neural representation of stimuli in damaged forebrain lost so animal doesn't respond to it (this stimuli would be in space contralateral to lesion)
- can -> circling because behavior neglect bc animal drawn to investigate stimuli ipsilateral to lesion so they drift toward side of lesion
82
subcortical forebrain lesions involving thalamus can cause
- proprioceptive circling or standing with head turned usually toward side of lesion
- WILL PROBABLY LACK HEAD TILT UNLIKE WITH VESIBULAR CIRCLING
