Lecture 9: Cerebellum Flashcards
How many cerebellar hemispheres?
Two (Left and Right)
brain structure
located behind the brainstem
Cerebellum ‘’Little Brain’’
cerebellum is also referred to as:
“little brain”
A primary function of the cerebellum is to:
Detect the difference between an intended
movement and the actual movement to reduce
“motor errors’’ (i.e., if there is a discrepancy,
the cerebellum can modify motor signals to
correct any errors).
A primary function of the cerebellum is to
detect the difference between an intended
movement and the actual movement to reduce
“motor errors’’ (i.e., if there is a discrepancy,
the cerebellum can modify motor signals to
correct any errors).
* These corrections can be made (2) :
(1) during
the course of the movement
(2) as a form of
motor learning when the correction is stored.
The cerebellum influences movements and
balance primarily by
modifying the activity
patterns of the upper and lower motor
neurons.
The two cerebral hemispheres (left and right) are further divided into (@:
(1) Anterior Lobe
(2) Posterior Lobe
What is the Deep Cerebellar Nuclei:
Clusters of cells in nuclei
buried deep in the white
matter of the cerebellum
Deep cerebellar nuclei contains (3):
(1) Fastigial nucleaus
(2) Interposed nuclei
(3) Dentate nucleus
Cerebellar hemispheres can
be divided into 3 parts:
(1) Cerebrocerebellum
(2) Spinocerebellum
(3) Vestibulocerebellum
Cerebrocerebellum:
most lateral zone of the cerebellar
hemisphere
Spinocerebellum::
Median zone of the cerebellar hemisphere
Spinocerebellum can be further divided into (2):
(1) Vermis (most median zone)
(2) Paramedian
Vermis (of the spinocerebellum):
Most median zone
Vestibulocerebellum
caudal inferior zone. includes the
Nodulus and Flocculus.
Vestibulocerebellum includes (2):
(1) Nodulus
(2) Flocculus
Cerebrocerebellum is the:
Most lateral part of
cerebellar hemisphere
Cerebrocerebellum receives indirect input from :
many areas of the CEREBRAL CORTEX
The cerebrocerebellum has what two main / general functions?
(1) Motor Functions
(2) Cognitive Funtions
Cerebrocerebellum: Motor Functions (2) :
➢Movement planning.
➢Coordination and execution
of complex spatial and
temporal sequences of
movement.
Cerebrocerebellum cognitive functions (3):
➢Motor learning
➢Attention
➢Monitoring sensations
Spinocerebellum includes (2):
(1) Vermis (median)
(2) Paramedian zone
Spinocerebellum receives direct input from:
the SPINAL CORD (proprioceptive information)
Spinocerebellum: Function:
Monitoring of ongoing
movements (i.e., position of the
body in space).
Participates in motor execution
VERMIS (median part of spinocerebellun) is involved with:
(1) Movement of the PROXIMAL MUSCLES
(2) movement of eyes
PARAMEDIAN ZONE (of the spinocerebellum) is involved with:
Movement of DISTAL MUSCLES (arm and leg muscles)
Phylogenetically, oldest
part of the cerebellum.
Vestibulocerebellum
What is the caudal-inferior lobe of the cerebellum
Vestibulocerebellum
Vestibulocerebellum includes (2):
Flocculus
Nodulus
Flocculo-nodular lobe:
Flocculus and nodulus of the vestibulocerebellum
Vestibulocerebellum receives input from:
VESTIBULAR NUCLEI in the
brainstem.
Receives input from
vestibular nuclei in the
brainstem
Vestibulocerebellum
Vestibulocerebellum: Function:
involved in the
regulation of movements
that MAINTAIN POSTURE,
BALANCE and EQUILIBRIUM
(e.g., VCR, VSR).
The connections between the
cerebellum and other parts of the
nervous system are made by:
THREE
large pipes called CEREBELLAR PEDUNCLES (fibers, white mater).
Cerebellar Peduncles keep:
the cerebellum attached to the
brainstem.
What are the three cerebellar peduncles?
(1) Superior cerebellar peduncle
(2) Middle cerebellar peduncle
(3)Inferior cerebellar peduncle
Superior Cerebellar Peduncle:
EFFERENT pathways (output)
Middle Cerebellar Peduncle:
➢ Afferent pathways (input).
➢ Main cortical input to the cerebellum
Inferior Cerebellar Peduncle:
Mixed pathways (afferent and efferent).
Corticopontocerebellar pathway:
* Transmits information to
the cerebellum
*Corticopontocerebellar pathway transmits information to the cerebellum from (3):
(1) motor
(2) premotor
(3) somatosensory
cortices via the pontine nuclei.
Corticopontocerebellar pathway informs:
the cerebellum of the INTENDED MOTOR ACTION made by the CORTEX.
Main cortical input to the cerebellum.
Middle Cerebellar Peduncle
Corticopontocerebellar pathway: the pathway enters the cerebellum through:
the middle cerebellar peduncle
Do fibers decussate in the corticopontocerebellar pathway?
yes
Corticopontocerebellar pathway projects mostly to:
the Cerebrocerebellum
Spinocerebellar pathway: transmits information from:
The periphery (e.g. muscles spindle, Golgi
tendon organs, joint receptors) via the spinal cord nuclei (Dorsal nucleus of Clarke & External cuneate
nucleus). Projects to the spinocerebellum.
Spinocerebellar pathway informs the cerebellum of:
the momentary status of muscle
contraction, muscle tension and limb position
Spinocerebellar pathway: The fibers enter the cerebellum through:
the inferior
cerebellar peduncle.
Decussation in the spinocerebellar pathway?
fibers DO NOT decussate
- Vestibulocerebellar pathway: transmits information from
the vestibular system
- Vestibulocerebellar pathway: projects to:
the vestibulo cerebellum
Vestibulocerebellar pathway:Informs the cerebellum of
the motion of the body
Vestibulocerebellar pathway: Fibers enter the cerebellum through:
the inferior cerebellar peduncle.
Decussation in vestibulocerebellar pathway:
Fibers DO NOT decussate
CorticoOlivocerebellar pathway: transmits information from the
cortex
CorticoOlivocerebellar pathway: transmits information from the cortex via
a the inferior olive nucleus.
CorticoOlivocerebellar pathway: participates in:
The learning and memory functions served by cerebellar circuitry
CorticoOlivocerebellar pathway:Projects to (2):
the Cerebrocerebellum and deep nuclei
CorticoOlivocerebellar pathway:The fibers enter the cerebellum through:
the
inferior cerebellar peduncle.
Fiber decussation in the CorticoOlivocerebellar pathway
Fibers Decussate
Cerebellar cortex neurons project
to
the deep cerebellar nuclei
(Dentate & interposed)
Deep cerebellar nuclei project
out
of the cerebellum through the
superior cerebellar peduncle into
two pathways:
Output via the Superior Cerebellar Peduncle:1st Pathway toward:
the primary motor &
premotor cortex, via the ventral lateral (VL)
complex nuclei of the thalamus.
Output via the Superior Cerebellar Peduncle:1st Pathway participates in:
planning and initiating voluntary
movements (i.e., helps the cortex to reduce
movement errors).
Output via the Superior Cerebellar Peduncle:1st Pathway toward:
superior
colliculus
Output via the Superior Cerebellar Peduncle:2nd Pathway participates in:
Modulates the activity of the
upper motor neurons concerned with eye
movement.
Output via the Inferior Cerebellar Peduncle:
Cerebellar-Vestibular Pathway
The cerebellum sends its outputs
into the:
vestibular nuclei through the
inferior cerebellar peduncle.
This pathway allows the cerebellum
to influence posture and equilibrium
(e.g., adjusting VCR, VSR, VOR
reflexes).
Cerebellar-Vestibular Pathway
The cerebellum sends its outputs
into the vestibular nuclei through the
inferior cerebellar peduncle
The cerebellar-vestibular pathway
plays a critical role in integrating and
modulating vestibular signals to (3):
➢ Enable adaptive changes to VCR, VSR
➢ Distinguish head tilts from translational
movements,
➢ Distinguish passive movements of the
head and body (reflexes) from those
that are self-generated (voluntary)
movements.
Purkinje cells in the cerebellar cortex
RECEIVE
INDIRECT EXCITATORY input
- Purkinje cells in the cerebellar cortex
receive indirect excitatory input from (2) :
(1) inferior olive through Climbing fibers
(2) pontine nuclei (cerebral cortex), spinal cord and
vestibular system through Mossy fibers and
Parallel fibers.
Purkinje cells process this information and
compare it with
the statute of ongoing
movement
Purkinje cells send
Inhibitory projection onto the deep cerebellar nuclei.
The deep nuclei cells send
excitatory
inputs onto motor cortex via the thalamus
The cerebellar neurons output to the motor
cortex generates
an error correction signal
that can modify movements
Activity of Purkinje cells and deep cerebellar
nuclear cells during wrist rest/movement: At resting state:
Both Purkinje
cell and deep cerebellar nuclei
cell are tonically active.
Activity of Purkinje cells and deep cerebellar
nuclear cells during wrist rest/movement: During movement of the wrist
(i.e., rapid alternating
movements)
both purkinje cell and deep cerebellar nuclei cell receive a transient inhibition
that blocks their tonic activity
Higher functions of the cerebellum: Cerebellum has role in (5):
➢Sensory acquisition,
➢Motor attention,
➢Timing of motor actions,
➢Prediction and preparation of movement,
➢Motor sequence learning and memory.
- Cerebellum is a __ structure.
helper
Higher functions of the cerebellum:Its circuitry could be acting as a :
predictor (i.e.,
predicts surrounding movements) and adjusts the
body movements accordantly.
Higher functions of the cerebellum: helps to coordinate motor actions
unconsciously
Pathophysiology of the Cerebellum:
Ataxia
Ataxia: Lack of voluntary coordination of muscle movements (e.g., failure to predict motor
movement, patients overshoot intended target):
dysfunction of the Cerebrocerebellum
Ataxia:* Loss of balance and gait difficulty: dysfunciton of:
the Vestibulocerebellum
Ataxia is a _ disease
genetic
integration of motor function =
coordinated movements
The cerebellum influences movements primarily by
modifying the activity patterns of upper and lower motor
neurons.
cerebellum detects:
the difference, or “motor error,” between an
intended movement and the actual movement (i.e.,
reduces movement errors).
cerebellum helps in motor coordination by:
parallel computations
(i.e., participates in the integration of motor function)
cerebellum role in motor cognition:
learning motor sequences,
memory of motor actions.
