Cerebellum
Cerebellum
Cerebellum
Cerebellum
Folium
Divisions of the Cerebellum
Ventral View Superior Surface
Ant Lobe
flocculus
Ant Lobe
nodulus
Schematic
Ant Lobe v
e
r
hemisphere m
Post Lobe i
s
flocculus
nodulus
Cerebellum
Primary fissure
Anterior Lobe
Regulation of
muscle tone,
coordination of
skilled voluntary
movement Posterior
Lobe
Planning of
voluntary activity Flocculo-Nodular
Lobe (FN lobe)
Maintenance of
Vestibulocerebellum
balance, control
of eye movements Spinocerebellum
Folia Cerebrocerebelum
Cerebellar Subdivisions
Archicerebellum-vestibulocerebellum
Paleocerebellum-spinocerebellum
Neocerebellum-pontocerebellum/cerebrocerebellum
Peduncles
ICP
Peduncle Connects
to
Superior Midbrain
(SCP)
SCP SCP
Middle Pons
MCP MCP
(MCP)
ICP ICP
Inferior Medulla
(ICP)
The Macroscopic Anatomy of the
Cerebellum
• Gross anatomical divisions
– Anterior lobe
– Posterior lobe
– Flocculonodular lobe
The Evolutionary & Functional
Division of the Cerebellum
• The cerebellum can be divided by
– Evolutionary age
– Function
Cerebellar Subdivisions
Archicerebellum-vestibulocerebellum
Paleocerebellum-spinocerebellum
Neocerebellum-pontocerebellum/cerebrocerebellum
Fast G E Dent
Simplified Cerebellar Circuitry
Spinal Cord, Cerebral Cortex +
(via pontine nuclei), Vestibular
Cerebellar Cortex
System
Mossy Fibers
INPUT -
Inferior Olive
Climbing Fibers Deep Cerebellar Nuclei
Mol Gr
Molecular
Cortex
Purkinje
WM
Granular
Stellate (inhibitory)
Basket (inhibitory)
(molecular layer)
Purkinje (inhibitory)
(Purkinje layer)
Golgi (inhibitory)
Granule (excitatory)
(Granular layer)
Inputs: Output:
• Climbing fiber (“+”, excitatory,
• Purkinje cell axon (“-”, inhibitory)
from inferior olive nucleus)
• Mossy fiber (+, from spinal cord
& brain stem)
Internal circuitry
A. Organization of
cortex is uniform
across different
subdivisions
B. AFFERENT
pathways to the
cerebellar cortex
excite Purkinje
cells.
C. Basket, stellate
and Golgi cells
regulate Purkinje
cell activity.
D. EFFERENT
pathways from the
cortex originate
from Purkinje
cells.
Purkinje Cell
complex spike
Second direct pathway:
• Mossy fiber (+) granule cells (axon: parallel fibers, +) Purkinje cells (-)
deep nuclei
• each parallel fiber projects to thousands of Purkinje cells (high divergence)
• each Purkinje cell receives input from ~200,000 parallel fibers (high
convergence)
• Weak excitatory connection, spatiotemporal summation of inputs from many
parallel fibers causes a single spike in Purkinje cell (called a “simple spike”)
simple spikes
glomeruli
Inhibition: focusing in time and
space
_ + _
Restiform Body
Posterior Spinocerebellar Tract
Olivocerebellar tract
Cuneocerebellar Tract
Reticulocerebellar Tract
Juxtarestiform Body
Vestibulocerebellar Tract
Cerebellum
Cerebellum
Connections
Connections
Pontocerebellar fiber
Fibers from raphe nuclei
Vestibular
Organ Floculonodular
Lobe
VESTIBULAR NUCLEUS Vermis
vestibulospinal tract
MLF FASTIGIAL
NUCLEUS
LMN
Main
MainConnections
Connectionsof
ofthe
thePaleocerebellum
Paleocerebellum
RED NUCLEUS
INTERPOSITUS
NUCLEUS
rubrospinal
tract Inferior ANTERIOR
Olivry LOBE
PARAVERMAL
Nucleus ZONE
CEREBRAL
CEREBRAL DENTATE
DENTATE
THALAMUS
THALAMUS
CORTEX
CORTEX NUCLEUS
NUCLEUS
pyramidal
tract Pontine
Pontine POSTERIOR
POSTERIOR
LOBE
Nucleus
Nucleus
LOBE
CEREBELLAR
CEREBELLAR
HEMISPHERE
HEMISPHERE
upper
uppermotor
motorneuron
neuron
UMN
UMN
BASAL
BASAL
Cerebellum
Cerebellum GANGLIA
GANGLIA
pyramidal tract
lower
lower motor
motor neuron
neuron
UMN
UMN
Cerebellum
Cerebellum and
andAutomatic
AutomaticMotor
MotorControl
Control
Motor
MotorCortex
Cortex
CEREBELLUM
CEREBELLUM
Red
RedNucleus
Nucleus
Reticular Vestibular
Vestibular
Reticular
Formation Nucleus
Nucleus
Formation
Lower
Lower Motor
MotorNeuron
Neuron(LMN)
(LMN) Proprioceptors
Proprioceptors
Cerebellum
Cerebellum
Connections
Connections
Olivocerebellar Connections
Caudal portion of
medial and dorsal accessory olivary nucleus
----------------- vermis of cerebellar cortex (A and B)
fastigial nucleus
vestibular nucleus
Rostral portion of
medial and dorsal accessory olivary nucleus
----------------- paravermal region (C1, C2, C3)
nucleus interpositus
Maintenance of Equilibrium
- balance, posture, eye movement
Cognitive Function
Cerebellum: Control of Voluntary Movement
All three lobes of cerebellum work together- Comparator of a servo-mechanism
Primary function:
1. To supplement & correlate the activities of other motor areas
2. Control of posture
3. Correction of rapid movements initiated by cerebral cortex
4. Motor learning
Frequency of nerve impulses in the climbing fibers almost
doubles when a monkey learns a new task
Movement Control:
a. Inputs from motor cortex inform the cerebellum of an intended
movement before it is initiated
b. Sensory information is then received via the
spinocerebellar tract
c. An error signal is generated and is fed back to the cortex
Cerebellum and Motor Learning
• Deficits in learning complex motor tasks
after cerebellar lesions
• fMRI studies : cerebellum active during
learning of novel movements
• Postulated that cerebellar nuclei store
certain motor memories
• May be involved in cognitive functions
Cerebellar Cognitive Function
• Plays a role in language and problem solving
• Recognizes and predicts sequences of events
Cerebellar Processing - 1
• The frontal motor association areas of the
cerebral cortex indicates its intents to
initiate voluntary muscle contractions
• Through collateral fibers of the pyramdial
tracts, it notifies the cerebellum of its
activity
Cerebellar Processing - 2
• At the same time, the cerebellum receives
information from the proprioceptors
throughout the body
– Tension in muscles, tendons, and joint positions
– From visual and equilibrium pathways
• This information enables the cerebellum to
determine where the body is and where it is
going
– More specifically where the parts of the body
are located in space and how are they moving
Cerebellar Processing - 3
• The cerebellar cortex assesses this
information and calculates the best way to
coordinate the force, direction, and extent
of muscle contraction
– Prevents overshoot
– Maintains posture
– Ensures smooth, coordinated movements
Cerebellar Processing - 4
• Via the superior peduncles, the cerebellum
dispatches its “blueprint” for coordination
to the cerebral motor cortex which makes
appropriate adjustments in its motor plan
• Cerebellar fibers also flow to brain stem
nuclei, such as the red nuclei of the
midbrain, which in turn project to motor
neurons of the spinal cord
The Cerebellum
• The cerebellum continually compares the
higher brain’s intention with the body’s
performance and sends out messages to
initiate the appropriate measures
• In this way, it helps to promote smooth
voluntary movements that are precise and
economical in terms of muscular effort
The Cerebellum
• Cerebellar injury results in the loss of
muscle tone and clumsy, unsure
movements, and sometimes even
impaired thoughts about movements
Clinical Considerations
• Signs of Dysfunction
– Impaired Muscle Synergy
– Reduced Muscle Tone
– Evident in Skilled Tasks
– Nystagmus
– Ataxia : incoordination of movement
- decomposition of movement
- dysmetria, past-pointing
- dysdiadochokinesia
- gait ataxia, truncal ataxia
• Slow Movement (Bradykinesia)
• Mild Muscular Weakness (Asthenia)
• Asynergia
• Speech difficulties (Ataxic Dysarthria)
– affects respiration, phonation, resonance and articulation, but
most pronounced in articulation and prosody.
Clinical Considerations 2
• Dysdiadochokinesia
– Clumsiness in Alternating Movements
– Tapping, Speech Sound
• Dysarthria
– Ataxic Dysarthria
– Scanning Speech
– Slurred and Disjointed Speech
• Dysmetria
– Error in Judgment of Range and Distance of Target
– Undershooting or Overshooting
Clinical Considerations 3
• Intentional Tremor
– Accessory Movement During Volitional Task
– vs. Parkinson’s Disease Where Tremor Lessens During
Volitional Movement
• Hypotonia
– Reduced Resistance to Passive Stretch
• Rebounding
– Inability to Predict Movement
– Cannot Hold Back Movement
• Disequilibrium
– Unsteady Gait, Body Wavering
Cerebellar Pathologies
• Cerebrovascular Accident (CVA)
– Thrombotic, embolic or hemorrhagic
– Vertebrobasilar Artery
• Toxicity
– Chronic Alcoholism
• Progressive Cerebellar Degeneration
– Friedrich's Ataxia: Autosomal Recessive
Heredity Degenerative Condition
– Combined Sensory and Motor Dysfunctions
Posture
Gait – Ataxia
Tremor
a b c
Cerebellar
Ataxia
b. Steady on the
right leg
c. Unsteady on the
left leg
d. ataxic gait
Cerebellar
Medulloblastoma