1. Coordination of movement
and Cerebellum
Prof. Vajira Weerasinghe
Professor of Physiology
Faculty of Medicine
University of Peradeniya
Y2S2 Locomotion module
2. Objectives
1. Discuss the role of the cerebellum on motor
coordination
2. Explain giving examples how coordination is
affected in neurological disease
4. Introduction
• the cerebellum and basal
ganglia are large collections of
nuclei that modify movement on
a minute-to-minute basis
• these regions have marked
similarities between them in the
overall pattern of their
connections with the cerebral
cortex
- both receive information from
the motor cortex
- both send information back to
cortex via the thalamus
5. Introduction
• the cerebellum sends excitatory
output to the motor cortex, while
the basal ganglia sends
inhibitory output
• the balance between these two
systems allows for smooth,
coordinated movement
- a disturbance in either system
will manifest itself as a
movement disorder
6. Functional significance of
cerebellum
• Functions outside conscious awareness
• Involved in coordinating motor activities and learning
new motor skills
• Particularly involved in adjusting activities to meet new
conditions
• May also be involved in other types of learning and in
emotional reactivity
7.
8. structure
• Cerebellum is divided into 3 lobes by 2
transverse fissures
– anterior lobe
– posterior lobe
– flocculonodular lobe
9.
10. • Anterior cerebellum and part of posterior
cerebellum
– receives information from the spinal cord
• Rest of the posterior cerebellum
– receives information from the cortex
• Flocculonodular lobe
– involved in controlling the balance through
vestibular apparatus
11.
12. • lateral zone
– this is concerned with overall planning of
sequence and timing
• intermediate zone
– control muscles of upper and lower limbs
distally
• vermis
– controls muscles of axial body, neck, hip
13. Inputs
• corticopontocerebellar
• from motor and premotor cortex (also sensory cortex)
• these tracts supplies the contralateral cerebellar cortex
• olivocerebellar
• from inferior olive
– excited by fibres from
» motor cx
» basal ganglia
» reticular formation
» spinal cord
14. Inputs (cont’d)
• vestibulocerebellar
• to the flocculonodular lobe
• reticulocerebellar
• to the vermis
• spinocerebellar tracts
– dorsal spinocerebellar tracts
• from muscle spindle, prorpioceptive mechanoreceptor (feedback
information)
– ventral spinocerebellar tarcts
• from anterior horn cell
– excited by motor signals arriving through descending tracts (efference
copy)
15. Outputs
• through deep cerebellar nuclei: dentate,
fastigial, interpositus
– 1. vermis -> fastigial nucleus -> medulla, pons
– 2. intermediate zone
-> nucleus interpositus
-> thalamus -> cortex
-> basal ganglia
-> red nucleus
-> reticular formation
– 3. lateral zone -> dentate nucleus
-> thalamus -> cortex
16.
17.
18. Neuronal circuitry of the cerebellum
• Main cortical cells in cerebellum are known as
Purkinje Cells (large cells)
• There are about 30 million such cells
• These cells constitute a unit which repeats
along the cerebellar cortex
19.
20.
21.
22.
23. • Somatotopic representation of the body is
present in cerebellar cortex although it is not as
clear as cerebral cortex
27. • Even at rest, Purkinje cells & deep nuclear cells
discharge at 40-80 Hz
• afferents excite the deep nuclear cells
• Purkinje cells inhibit the deep nuclear cells
28. Functions of cerebellum
• planning of movements
• timing & sequencing of movements
• control of rapid movements such as walking
and running
• calculates when does a movement should
begin and stop
29. Overview of motor system
hierarchy
1. Motor areas in the cerebral cortex
30. Overview of motor system
hierarchy
1. Motor areas in the cerebral cortex
2. Brainstem
31. Overview of motor system
hierarchy
1. Motor areas in the cerebral cortex
2. Brainstem
3. Spinal cord
motor circuits
rhythmic movements reflexes voluntary movements
32. Overview of motor system
hierarchy
1. Motor areas in the cerebral cortex
2. Brainstem
3. Spinal cord
motor circuits
rhythmic movements reflexes voluntary movements
33. Overview of motor system
hierarchy
1. Motor areas in the cerebral cortex
2. Brainstem
3. Spinal cord
motor circuits
rhythmic movements reflexes voluntary movements
Cerebellum Basal ganglia
34. Overview of motor system
hierarchy
1. Motor areas in the cerebral cortex
2. Brainstem
3. Spinal cord
motor circuits
rhythmic movements reflexes voluntary movements
Cerebellum Basal ganglia
Thalamus
35. ‘Error correction’
• cerebellum receives two types of information
– intended plan of movement
• direct information from the motor cortex
– what actual movements result
• feedback from periphery
– these two are compared: an error is calculated
– corrective output signals goes to
• motor cortex via thalamus
• brain stem nuclei and then down to the anterior horn cell
through extrapyramidal tracts
36. • ‘Prevention of overshoot’
– Soon after a movement has been initiated
– cerebellum send signals to stop the
movement at the intended point (otherwise
overshooting occurs)
• Ballistic movements
– movements are so rapid it is difficult to decide
on feedback
– a high-velocity musculoskeletal movement,
such as a tennis serve or boxing punch,
requiring reciprocal coordination of agonistic
and antagonistic muscles
– rapid movements of the body, eg. finger
movements during typing, rapid eye
movements (saccadic eye movements)
37. planning of movements
• mainly performed by lateral zones
• sequencing & timing
– lateral zones communicate with premotor areas, sensory
cortex & basal ganglia to receive the plan
– next sequential movement is planned
– predicting the timings of each movement
• compared to the cerebrum, which works entirely on a
contralateral basis, the cerebellum works ipsilaterally
38. Motor learning
• the cerebellum is also partly responsible for
learning motor skills, such as riding a bicycle
- any movement “corrections” are stored as part of
a motor memory in the synaptic inputs to the
Purkinje cell
- research studies indicate that cerebellum is a
pattern learning machine
- cellular basis for cerebellum-dependent motor
learning is know to be a type of long-term
depression (LTD) of the Purkinje cell synapses
39. Neurotransmitters
• Excitatory: glutamate
» (Climbing, mossy, parallel fibres)
• Inhibitory: GABA
» (Purkinje cell)
• Serotonin and Norepinephrine are also known
to be involved
41. features of cerebellar disorders
• ataxia
– incoordination of movements
– difficulty in regulating the force, range, direction,
velocity and rhythm of movements
– It is a general term and may be manifested in any
number of specific clinical signs, depending on the
extent and locus of involvement
– limb movements, gait, speech, and eye movements
may be affected
42. features of cerebellar disorders
• ataxic gait
• broad based gait
• leaning towards side of the lesion
• dysmetria
• cannot plan movements
• abnormal finger nose test
• past pointing & overshoot
• cannot stop at the intended point and thus overshoot
results
43. features of cerebellar disorders
• decomposition of movements
• movements are not smooth
• decomposed into sub-movements
• intentional tremor
• at rest: no tremor
• when some action is performed: tremor starts
44. features of cerebellar disorders
• dysdiadochokinesis
• unable to perform rapidly alternating movements
• dysarthria
• slurring of speech
• scanning speech
• nystagmus
• oscillatory movements of the eye
45. features of cerebellar disorders
• hypotonia
– reduction in tone
• particularly in pure cerebellar disease
• due to lack of excitatory influence on gamma motor
neurons by cerebellum
• pendular jerks
• legs keep swinging after a tap
• rebound
• increased range of movement with lack of normal recoil to
original position
46. features of cerebellar disorders
• titubation
• head tremor
• truncal ataxia
• patients with disease of the vermis and flocculonodular
lobe will be unable to stand at all as they will have truncal
ataxia
48. Spino Cerebellar Ataxia (SCA)
• Hereditary
• May be autosomal dominant or recessive
• About 50 types of spinocerebellar ataxia present
• Some types can be pure cerebellar
• Ataxia results from variable degeneration of neurons
in the cerebellar cortex, brain stem, spinocerebellar
tracts and their afferent/efferent connections
50. Alcoholic Cerebellar Degeneration
• Estimated overall prevalence of alcohol dependence is
0.5–3% of the population in Europe or USA
• Central and peripheral nervous systems are the two
principal targets
• Chronic alcohol ingestion can impair the function and
morphology of many brain structures particularly
cerebellum
51. Alcoholic Cerebellar Degeneration
• Both acute and chronic ingestion of alcohol result in
cerebellar dysfunction
• Main complaint in patients presenting alcohol-induced
cerebellar dysfunction is difficulty in standing and
walking
53. Clinical examination of cerebellar
functions
• Gait (broad-based)
• Muscle power (normal)
• Muscle tone (hypotonia)
• Finger-nose test (abnormal)
• Heel-knee-shin test (abnormal)
• Rapid alternating movements (abnormal)
• Speech (dysarthria)
• Eye movements (nystagmus)
• Reflexes (pendular)
• Rebound phenomenon
54. • ROMBERG TEST IS NOT A SIGN OF
CEREBELLAR DISEASE
– It is a sign of a disturbance of proprioception, either
from neuropathy or posterior column disease
– Patient does not know where their joint is in space
and so uses their eyes
– In the dark or with eyes closed they have problems
