Cerebellum Lecture

Question 1

Main function of the cerebellum

Answer 1

• Motor coordination and correction
• Maybe motor memory component
• able to test directly

Question 2

Main function of the Basal Ganglia

Answer 2

• Initiation Selection of Motor Programs
• Cannot test directly

Question 3

Corticospinal tracts

Answer 3

One long axon. Modulation is performed by spinal cord, thalamus (BG and cerebellum)

Question 4

where does the cerebral cortex send info to

Answer 4

• the spinal cord
• the BG
• Cerebellum

Question 5

what does the BG send info to

Answer 5

• thalamus
• brainstem

Question 6

what does the cerebellum send info to

Answer 6

• thalamus
• brainstem

Question 7

what does the spinal cord send info to

Answer 7

the cerebellum and the thalamus

Question 8

what is the motor control of the cerebellum

Answer 8

1) maintenance of balance and posture: Vestibular information/ proprioception
2) Coordination of multiple motor groups/ movement. Skilled movement
3) proprioception input: muscle spindle feedback (muscle proprioception
4) Postural Adjustments: Unconscious GTO
5) sensory processing
6) adaptability
7) automaticity: especially in posture
8) motor commands are not initiated in cerebellum; it modifies motor activity accuracy

Question 9

Motor Learning of the Cerebellum

Answer 9

The cerebellum plays a major role in adapting and fine-tuning motor programs to make accurate movements through a trial-and-error process

Question 10

Cognitive Functions of the Cerebellum

Answer 10

Involved with cognitive functions such as language. Historically it is considered part of the motor system but cognitive functions are not fully understood yet.

Question 11

the 4 inputs of the cerebellum

Answer 11

1) anticipates the output of the motor command (coordination of joints)
2) requires proprioception from the muscle spindles
3) requires vestibular information for control of balance and equilibrium
4) controls eye reflexes (fixation on a target and eye coordination

Question 12

what is the forward model of the cerebellum

Answer 12

predicts the sensory outcome of our movement and actions

Question 13

The accuracy in time sensorimotor coordination

Answer 13

• is like a copy machine: It creases a replica of our movement in time and produces a “likeness of the pattern”
• If the motor performace has error: the cerebellum corrects via error based learning

Question 14

Essential aspects of sensorimotor coordination of the cerebellum

Answer 14

• timing
• onset and offset of muscle activation
• direction of movement

Question 15

although the cerebellum accounts for (x%) of the brains volume, it contains over (y%) of the total number of neurons in the brain

Answer 15

x 10%
y 50%

Question 16

what sensory input helps compensate for shifts in the body position of changes in load upon the muscles

Answer 16

input from the vestibular receptors and muscle proprioceptors (muscle spindle and GTO)

Question 17

Lobes of the Cerebellum

Answer 17

medial to lateral
1) vermis
2) intermediate zone
3) lateral hemisphere
inferior
4) flocculonodular lobe

Question 18

what does the flocculonodular lobe connect directly to

Answer 18

the vestibular system

Question 19

function of the flocculonodular lobe

Answer 19

1) transport vestibular information
2) equilibrium balance
3) posture

Question 20

Lateral hemisphere function and motor pathway

Answer 20

function: motor planning for extremities
Pathways: lateral corticopinal tracts

Question 21

Intermediate hemispheres function and motor pathway

Answer 21

function: distal limb coordination
pathways: lateral corticospinal tract and rubrospinal tract

Question 22

vermis function

Answer 22

proximal limb and trunk coordination

Question 23

flocculonodular lobe funciton

Answer 23

balance and vestibuloocular reflexes

Question 24

Purkinje Cells

Answer 24

output from the cerebellum
inhibitory

Question 25

Climbing fibers

Answer 25

input to the cerebellum from olive excitatory

Question 26

Mossy fibers

Answer 26

input to the cerebellum excitatory

Question 27

Main cerebellar input pathways

Answer 27

1) vestibular input: balance and equilibrium 2) visual (corticopontine fibers) 3) proprioceptive and somatosensory (corticopontine fibers) 4) motor efference copy

Question 28

Main cerebellar outputs

Answer 28

1) thalamus 2) hippocampus 3) superior colliculus 4) premotor areas 5) primary motor area 6) posterior parietal cortex

Question 29

function of the superior colliculus

Answer 29

learning memory and connections

Question 30

direct vestibular cerebellar connections

Answer 30

From vestibular receptors in the semicircular ducts - Vestibular ganglion - into rostral medulla - vestibular complex - follocculonodular

Question 31

inputs tracts to the cerebellum

Answer 31

1) ventral spinocerebellar 2) Dorsal spinocerebellar 3) cuneo spinocerebellar 4) rostral spinocerebellar

Question 32

Ventral Spinocerebellar Tract

Answer 32

- from LE - leg interneuron - coordinates movement and posture - unconscious perception - crosses twice

Question 33

Dorsal Spinocerebellar Tract

Answer 33

- from LE - leg proprioceptors - Carry MS and GTO info (1a and 1b) - carry proprioception, touch, and pressure sensation - stays unilateral

Question 34

Rostral Spinocerebellar Tract

Answer 34

- from UE - information for coordinated movement - Arm interneurons - unilateral tract

Question 35

Cuneo Spinocerebellar Tract

Answer 35

- From UE - arm proprioceptors - 1a MS proproceptive, touch and pressure sensation - unilateral tract

Question 36

Cerebellum outputs

Answer 36

- no direct connection from the motor system 1) red nucleus to spinal cord 2) ventrolateral nucleus (VLN) of thalamus to cortex

Question 37

what areas of the cortex does the ventrolateral nucleus of the thalamus connect too

Answer 37

- premotor cortex - supplementary cortex - prefrontal association area Function: to in in postural control, smooth movements, feedback for error

Question 38

lesions of the cerebellum will present problems on what side

Answer 38

the unilateral side

Question 39

Deficits in cerebellar function

Answer 39

- uncoordination and problems maintaining balance and posture - decomposition of movement -Intention tremor

Question 40

decomposition of movement definition

Answer 40

- unable to produce coordinated and smooth movements. - Loss of feedforward mechanism , does not allow or temoral timing of the activated muscles, force or awareness in space - Ataxia

Question 41

Intention tremor

Answer 41

when making a movement toward a target the pt might produce an involuntary movement tremor that increases as they approach closer to the target

Question 42

Types of Cerebellar Testing

Answer 42

- Finger to nose - Heel to shin - Dysdiadochominesia (RAM) - Romberg - Rapid finger tapping movements

Question 43

What do look for in cerebellar exams

Answer 43

- speed, coordination, timing (heel to shin) and (finger to nose)

Question 44

Dysrhythmia

Answer 44

abnormal timing

Question 45

Dysmetria

Answer 45

overshoot or past pointing

Question 46

Dysdiadochokinesia

Answer 46

RAM (supination and pronation)

Question 47

Overshooting

Answer 47

holding a testing position and suddenly letting go

Question 48

Truncal ataxia

Answer 48

ataxia in gait

Question 49

postural dysfunction in cerebellar disorders

Answer 49

- high fall risk - loss of automatic movements - loss of ankle, hip strategies (due to lack of muscular timing) - static and dynamic posture - may have increased tone or reflexes

Question 50

Hypotonia

Answer 50

low tone from loss of MS and GTO input

Question 51

slow generation of force

Answer 51

unable to produce timely force generation (5/5 strength throughout but mild slowly)

Question 52

loss of RAM

Answer 52

inability to produce RAM

Question 53

Deficits in motor learning

Answer 53

loss of the ability to anticipate (feedforward) or correct (feedback) because of loss of proprioceptive, sensory and muscle force

Question 54

how does the cerebellum predict sensory and motor outcomes of a task

Answer 54

sensory via: MS and GTO Motor: input from vision: task is an error