Cerebellum

Question 1

disorders to the cerebellum results in ?

general- in comparison to cerebrum

Answer 1

disruption of normal movement - NOT abolishment

these disruptions are in stark contrast to the paralysis caused by damage to the cerebral cortex

Question 2

what are the 4 common manifestations of lesions to the cerebellum?

Answer 2

1- hypotonia (related to “pendular reflexes”)

2- an inability to stand or walk

• atasia
• abasia

3- ataxia (abnormal execution of multi-jointed voluntary movements)

4- intension tremor (action tremor) and terminal tremor

Question 3

what is atasia?

Answer 3

loss of the ability to maintain a steady limb or body posture

Question 4

what is abasia?

Answer 4

loss of the ability to maintain upright stance against gravity

Question 5

what are the pendular reflexes?

Answer 5

tap knee with hammer, should get a stretch reflex

if there is a lesion in the cerebellum, reflex would continue – going back and forth before your knee relaxed

Question 6

what are the general functions of the cerebellum?

Answer 6

Regulates- force and timing of motor activities

Helps with the range and direction of motor movements

Allows for the rapid progression from one movement to the next

Sequencing of motor movements

Agonist-antagonist interplay (synergy)

Help with planning of movements

Helps with the maintenance of upright posture

Motor Learning

Subconscious movement

appears to function as a comparator- compensates for errors (internal and external feedback) in movements

*changed by experience- thus plays a role in learning motor tasks

Question 7

cerebellum controls the controller in a feedforward manner.. what does this mean?

Answer 7

corrects for all the errors as the messages are being sent down- makes the corrections BEFORE the LMNs get it

feedback is after the action has already happened

dynamic- changes by experience

(doesn’t connect directly to LMNs- sends its coordination inputs to the control centers- vestibular nuclei, etc.)

Question 8

what are the 3 functional divisions?

Answer 8

1- vestibulo cerebellum

2- spinocerebellum

3- cortico cerebellum

Question 9

what lobe controls the vestibulo cerebellum division?

where does it receive projections from?

Answer 9

flocculonodular lobe
“archicerebellum” (oldest part of the structure phylogenetically) (fishO)

flocculonodular lobe receives many projections from the vestibular nuclei

Question 10

what are the functions of the vestibulo cerebellum division?

Answer 10

coordinate head and eye movement

body equilibrium- help with the maintenance of balance

Question 11

what are the afferent components of the vestibulo cerebellum system?

Answer 11

vestibular system
vestibular apparatus
visual centers- superior colliculus, lateral geniculate and striate cortex

Question 12

what are the efferent components of the vestibulo cerebellum system?

Answer 12

vestibular nuclei- responsible for maintaining posture

reticular formation

Question 13

what lobe controls the spinocerebellum function division?

what is the corresponding nucleus?

Answer 13

the anterior lobe (vermal portion) and the intermediate areas of the hemispheres

“paleocerebellem” second oldest part phylogenetically (reptiles)

nucleus=
fastigial- to medial descending systems
interposed- to lateral descending systems

Question 14

what are the functions of the spinocerebellum division?

Answer 14

controls medial and lateral components of the descending motor system and thus plays a role in the EXECUTION ongoing limb movements

regulates muscle tone

(axons come from SC (all the dorsal, ventral, rostral, cuneo, reticular cerebellar tracts)

Question 15

what is the somatotopical arrangement for the spinocerebellum division?

Answer 15

vermis= eyes and trunk

lateral to vermis= axial musculature

Question 16

what are the afferent components of the spinocerebellum division?

Answer 16

vermis- visual, hearing, vestibular

hemispheric- spinocerebellar and reticulocerebellar tracts

Question 17

what are the efferent components of the spinocerebellum division?

Answer 17

BS motor nuclei (red nucleus, RF, etc)

Question 18

what lobe controls the corticocerebellum functional division?

what is the corresponding nucleus?

Answer 18

posterior lobe
“pontocerebellum”
“neocerebellum”

largest

nucleus- dentate nucleus- to motor and premotor cortices

Question 19

what are the functions of the corticocerebellum division?

Answer 19

planning and (cortex-initiation of movements)

learning and storage

precision in the control and rapid movements and fine dexterity

concerned with preparation of movement

Question 20

what are the afferent components of the corticocerebellum division?

Answer 20

pontocerebellar

pontine nuclei directly associated

Question 21

what are the efferent components of the corticocerebellum division?

Answer 21

dentothalamic fibers (cerebellothalamocortical fibers)

Question 22

explain the motor loop through the lateral cerebellum:

Answer 22

???

pontine nuclei
-axons from layer V pyramidal cells in the sensorimotor cortex form massive projections to the pons

corticopontocerebellar projection
-20x larger than pyramidal tract

function
-execution of planned, voluntary, multipoint movements

Question 23

what are the cerebellar outputs?

Answer 23

fastigial nucleus to medial descending systems
interposed nucleus to lateral descending systems
BOTH –> motor execution

dentate nucleus to motor and premotor cortices –> motor planning

vestibular nuclei –> balance and eye movements

Question 24

what are the cerebellar inputs?

Answer 24

corticopontine inputs
spinal and trigeminal inputs
visual and auditory inputs
vestiular inputs

Question 25

what is the circuitry of the vestibulo cerebellum?

Answer 25

from the flocculonodular lobe descends through the superior cerebellar peduncle to the vestibular nucleus to the MLF and descends the medial vestibulospinal tracts

afferents:
vestibular receptors –> vestibular nucleus up the inferior cerebellar peduncle to the flocculonodular lobe

Question 26

what is the circuitry of the spino cerebellar division?

Answer 26

controlling and stabilizing axial and proximal musculature
coordinates movements of distal extremities via the red nucleus

more for execution of movement

Question 27

what is the circuitry of the corticocerebellar division?

Answer 27

these systems come from the cortex, they are the largest

project down to the pons to pontine nuclei then refers info to pontine cerebellar

neocerebellum (ahead of time) motor nucleus monitors what is going on (activity goes on before movement is initiated

cerebral cortex–> ponto system –> pons to hemispheres to dentate –> cerebral cortex –> out foraminal tracts

Cortex asks cerebellum, ‘this is my intention, how do I do it?’, cerebellum makes prediction of best way of doing something under environmental factors, sends info back to cortex, initiates movement

Question 28

what are the results of a vestibulo cerebellum disorder?

Answer 28

decreased equilibrium
ataxic gait- upright posture

wide base of support
less of a problem in a gravity eliminated environment

pathological nystagmus

-romberg

Question 29

what are the results of a spinocerebellum disorder?

Answer 29

hypotonia- primarily decrease is in gamma MN drive

titubation- staggering in trying to walk
-vermis and intermediate zones
ataxia of axial and proximal muslces
-gravity=unrelated
-usually worse on LE

balance problems due to inability to coordinate

Question 30

what are the results of a corticocerebrellum disorder?

Answer 30

delays in initiation and termination of movement

intention tremor (increases toward the ends of movements)

disorders in the temporal coordination of movements involving multiple joints

disorders in the spatial coordination of hand and finger ms

dysmetria- errors in range and force of movements (overshoot and undershoot)

timing is off

ataxia

dysdiadochokinesia- can’t rapidly alternate between movements

decomposition of movement (multi joints)- not bracing proximal joints against forces

normal rhythm and flow of movement is decreased
-slurred speech and broken syllables

dysarthria- due to vermis control of facial muscles

Question 31

lesions of inferior olive complex:

Answer 31

precise function unknown

usually associated with pyramidal tracts- therefore over shadowed

olivocerebellar degeneration-exception
disorder begins about 40-50
olive atrophies and results in:
-contralat progressive ataxia of extremities 
-intention tremor
-dysarthria may develop
-motor learning??

Question 32

what are other functions of the cerebellum?

Answer 32

cognitive computation independent of motor execution (timing of serial events)

lesions of lateral cerebellum caused inability to learn a word-association task

limbic system

• affective changes occur during cerebellar lesions:
• anxiety, aggression, hyper spontaneous disinhibited behavior, etc- disorders of emotional control