Cerebellum and
pathways
Objectives - cerebellum

Identify the anatomical divisions of the cerebellum

Identify the functional divisions of the cerebellum

Explain what observable functions each division of the cerebellum is involved with

Describe each afferent and efferent pathway – structure, function, neurotransmitters, and neuron
type if applicable

Describe or draw the layers of the cerebellar cortex

Describe or draw the types of neurons in the cerebellar cortex

Identify which neurons are excitatory (glutamate & aspartate) and which are inhibitory (GABA)

Explain how the neurons in the cerebellar cortex interact
Plan of attack

Lecture 9 – cerebellar structure and organization, afferent cerebellar
pathways, efferent cerebellar pathways

Lecture 10 –cerebellar histology, motor learning
Overall function

Ataxia with intention (action) tremor:


Ataxia with gross limb movement dysfunction:


https://www.youtube.com/watch?v=FpiEprzObIU
Dysmetria:


https://www.youtube.com/watch?v=qKGicpQLt6M
Ataxic Gait:


https://www.youtube.com/watch?v=5eBwn22Bnio
https://www.youtube.com/watch?v=jnQcKAYNuyk
Dysdiadochokinesia:

https://www.youtube.com/watch?v=gNZFSUdL_uc
Anatomical structure


Gray Cortex! (Folia = sulci and gyri)

Floculonodular lobe

Anterior lobe

Posterior lobe
White Matter


Cerebellar peduncles -> Arbor Vitae
(tree of life!)
Deep Nuclei

4 total (per hemisphere)
View of entire cortex
Functional structure



Vestibulocerebellum (floculonodular lobe)

Balance during stance/gait, coordinates eye and body
movements

Associated with vestibular nuclei
Spinocerebellum (vermis and paravermis)

Coordination of limb movements

Associated with spinal cord directly and indirectly
Cerebrocerebellum (lateral hemispheres)

Planning and preparation for movement, fine motor control

Associated closely with motor cortex (pre-central gyrus)
Cerebellar nuclei

Lateral – Dentate

Middle – Interposed;
Emboliform and Globose

Medial – Fastigial
Nuclei connections

Fastigial – vestibulocerebellum to vestibular
nuclei and eye motor centers

Interposed – spinocerebellum to contralateral
red nucleus


Dentate – cerebrocerebellum to thalamus


Rubrospinal tract
Planning and control of voluntary movements
All cerebellar efferents synapse in the deep
nuclei
The nodulus connects to which nucleus?
94%
6%
De
nt
at
e
0%
bo
lif
or
m
0%
Em
D.
e
C.
Gl
ob
os
B.
Fastigial
Globose
Emboliform
Dentate
Fa
st
ig
ia
l
A.
Your patient has difficulty with fine motor
control. Which nucleus would be associated?
97%
0%
De
nt
at
e
0%
bo
lif
or
m
3%
Em
D.
e
C.
Gl
ob
os
B.
Fastigial
Globose
Emboliform
Dentate
Fa
st
ig
ia
l
A.
Which part of the cerebellum would be
associated with the same patient?
100%
re
br
oc
er
eb
el
lu
m
0%
Ce
0%
Sp
in
oc
er
eb
el
lu
m
C.
ib
ul
oc
er
eb
el
lu
m
B.
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
Ve
st
A.
Cerebellar Afferents

4 Spinocerebellar Tracts

Pontocerebellar

Reticulocerebellar

Raphecerebellar

Hypothalamocerebellar

Ceruleocerebellar

Olivocerebellar
Spinocerebellar Tracts (cross-section)
Cuneocerebellar Pathway

Information ascends in the cuneate tract

Synapses in the Accessory cuneate nucleus
(lateral to the cuneate nucleus in the medulla)

Second neuron ascends ipsilaterally through ICP
to cerebellar nuclei and cortex

Entire pathway is IPSILATERAL

Carries sensory information from UE
Posterior Spinocerebellar Pathway

Ascends ipsilaterally in PSC tract

Synapses in spinal cord

Passes through ICP

Ends in cerebellar cortex and nuclei

Carries sensory information from LE
Rostral Spinocerebellar Pathway

Ascends ipsilaterally

Runs with cuneocerebellar, and then splits and runs with ASC after it
crosses

Enters cerebellum through SCP (like ASC)

Carries sensory information from UE
Anterior Spinocerebellar Pathway

Ascends contralaterally in ASC tract

Crosses through the SCP

Ends in ipsilateral cerebellar cortex and nuclei

Carries sensory information from LE
Which pathway carries sensory information to
the cerebellum from the UE and goes through
the SCP?
100%
0%
tro
ce
re
be
lla
r
0%
Ro
s
0%
PS
C
D.
la
r
C.
Cu
ne
oc
er
eb
el
B.
ASC
Cuneocerebellar
PSC
Rostrocerebellar
AS
C
A.
The ICP is damaged. Which of the following is
TRUE?
in
fo
fro
m
...
bo
t..
.
in
fo
Co
nt
ra
la
te
ra
ls
en
so
ry
en
so
ry
to
in
fo
en
so
ry
Ip
sil
at
er
al
s
0%
fro
m
th
e.
..
c..
.
th
e
to
in
fo
D.
0%
Co
nt
ra
la
te
ra
ls
C.
19%
en
so
ry
B.
Ipsilateral sensory info to the
cerebellum from the UE is completely
gone.
Contralateral sensory info to the
cerebellum from the LE is completely
gone.
Ipsilateral sensory info from both limbs
is reduced.
Contralateral sensory info from both
limbs is reduced.
Ip
sil
at
er
al
s
A.
81%
Spinocerebellars

Which is the red?

Which is the blue?

Which is the green?

Which is missing and where would it be?

All MOSSY FIBERS
Other cerebellar afferents

Pontocerebellar

Reticulocerebellar

Raphecerebellar

Hypothalamocerebellar

Ceruleocerebellar

All MOSSY FIBERS
Olivocerebellar Pathway

Information from Inferior Olivary Nucleus

Crosses to the ICP

Ends in the cerebellar cortex and nuclei

CLIMBING FIBERS
Which of the following do NOT connect to the
#reticular formation?
49%
C.
D.
E.
5%
0% 2%
ru
le
oc
er
eb
el
la
r
Po
nt
oc
er
eb
el
la
r
Ra
ph
ec
er
eb
el
la
Re
r
tic
ul
oc
er
Hy
eb
po
el
la
th
r
al
am
oc
er
eb
el
la
r
B.
Ceruleocerebellar
Pontocerebellar
Raphecerebellar
Reticulocerebellar
Hypothalamocerebellar
Ce
A.
44%
Cerebellar afferent Drawing!

Split the 4 spinocerebellars into 2 groups – draw 2 pathways per image

Either by LE vs. UE, or by similar pathways (Cuneo and Post., Rostral and Ant.)

Draw olivocerebellar tracts

Add essential information to each drawing along the side:

Where does the pathway decussate (if it does)?

Which cerebellar peduncle does it go through?

What information does it carry?

What type of fibers is it? (mossy or climbing)
Cerebellar efferents

Corticonuclear

Nucleocortical

Corticovestibular

Other efferents
Cerebellar Corticonuclear
Pathway “Fibers”
LC = Lateral
Cortex
Cerebellar cortex (Purkinje
cells) → cerebellar nuclei
Cerebellar Nucleocortical
Pathway “Fibers”
Cerebellar nuclei neurons
(Nuclei Cells) → cerebellar
White
Matter =
Arbor
Vitae
IC =
Intermediat
e Cortex
VC =
Verma
l
Cortex
Cerebellar Corticovestibular
Pathway
o Starts in:

Purkinje cells within vermis, nodulus, &
focculonodular lobe (Cerebellar
Cortex)
o Through Inferior Cerebellar Peduncle
o Ends in:

Vestibular nuclei within the brainstem
All of the neurons with somas in the deep
cerebellar nuclei exit the cerebellum.
91%
A. True
B. False
Fa
lse
Tr
ue
9%
The corticovestibular tract is from the cerebellar
cortex directly to the vestibular nuclei.
97%
A. True
B. False
Fa
lse
Tr
ue
3%
Conclusion

Read for Wednesday


L-E ch. 11 pt. 1
We will discuss cerebellar histology Wed. and talk about how the plasticity plays a role a
motor learning!
Nuclear Efferents

Dentate and Interposed nuclei

Neurons cross in SCP

Go to Thalamus, Pontine nuclei, Reticular
formation, Red nucleus, Olivary bodies,
Oculomotor complex (nystagmus)

From thalamus up to cerebral cortex

From other structures, straight down the spinal cord
Cerebellar Efferent Fibers & Motor
Control
1. Cerebellorubral route connects the rubrospinal route
•
cerebellum → red nucleus → SC
2. Cerebelloreticular route connects the reticulospinal route
•
cerebellum → reticular formation → SC
3. Cerebellothalamic route connects the thalamocortical route
Which then connects to the corticospinal route
•
cerebellum → thalamus → cortex → SC
*Cerebellar nuclei influence motor control
Takeaways – cerebellar efferents

All efferents from cerebellar nuclei (Dentate, Interposed, Fastigial)

Fastigial goes to vestibular nuclei


Bilateral
Dentate and interposed go to thalamus, red nucleus, pontine nuclei, olivary nuclei, and #RF

All decussate in SCP

All decussate again to go down spinal cord

All information ends up being IPSILATERAL
Which of the following are bilateral tracts?
0%
0%
tro
sp
in
oc
er
eb
el
la
r
Co
rt
ico
ve
st
ib
ul
ar
0%
la
r
0%
Ro
s
Ol
iv
oc
er
eb
el
D.
la
r
C.
oc
er
eb
el
B.
Hypothalamocerebellar
Olivocerebellar
Rostrospinocerebellar
Corticovestibular
Hy
po
th
al
am
A.
Objectives - cerebellum

Identify the anatomical divisions of the cerebellum

Identify the functional divisions of the cerebellum

Explain what observable functions each division of the cerebellum is involved with

Describe each afferent and efferent pathway – structure, function, neurotransmitters, and neuron
type if applicable

Describe or draw the layers of the cerebellar cortex

Describe or draw the types of neurons in the cerebellar cortex

Identify which neurons are excitatory (glutamate & aspartate) and which are inhibitory (GABA)

Explain how the neurons in the cerebellar cortex interact
Histology!

Cerebellar cortex histology, once
understood, gives a really awesome and
essential understanding to motor learning!

3 layers of cerebellar cortex

Molecular (outer) layer

Purkinje layer

Granular (inner) layer

Zoomed in!

Reference: White area is
air – outside the folia
(a sulcus)

Notice:

molecular layer,

purkinje cells,

granular layer
Molecular layer

Parallel fibers (axons of granular cells,
telephone wires)

Climbing Fibers (like vines on the purkinje tree)

Dendrites of purkinje cells (tree like)

Basket and Stellate cells
Purkinje layer

Purkinje somata
Granular layer

Granule somata

Golgi cells

Zoomed in!

Reference: White area is
air – outside the folia
(a sulcus)

Notice:

molecular layer,

purkinje cells,

granular layer
Afferent fibers

Information coming IN!!

Climbing Fibers (vines)

Mossy Fibers (stimulate granule cells)
Mossy fibers (afferent pathways)

Come from all afferent pathways except olivocerebellar


List them!
Excite granular cells (parallel fibers, telephone wires) with high frequency,
weak EPSP

glutamate

Bring in information constantly on what’s planned and what’s actually
happening with somatic motor control

Like the internet, all information is transmitted through telephone cable
system
Climbing fibers (olivocerebellar)

Powerful excitation to purkinje cells (vines on purkinje tree)

glutamate

Respond to interruptions in balance (from reflexes in spinal cord)

Olivocerebellar

Only fire when an immediate reaction is required!

Like the CIA when something important is found on the internet!
Granule cells

Granule cells (parallel fibers in molecular layer)

Telephone wires

All run parallel, highly structured in cortex
Granule cells

Soma is in granular layer

Axon ascends to molecular layer, splits, and
runs as parallel fiber

Excitatory but weak to purkinje cells – requires
multiple action potentials to break threshold

glutamate
Purkinje neurons

Named after one of the first neuroscientists

Main efferent neurons (cortex to deep
cerebellar nuclei)

Have a huge dendritic tree in the molecular
layer

Are acted on by:

Parallel fibers

Climbing fibers
Efferent fibers

Purkinje neurons (inhibitory)

GABA

Giant dendritic tree

Weak but frequent stimulation from granule cells


Strong but infrequent stimulation from climbing fibers


Which pathways?
Which pathways?
Inhibit deep nuclei (DEGF)
Inhibitory interneurons

Basket cells


Inhibit purkinje cells
Golgi cells

Inhibit granule cells

All GABA
Basket cells

Axon terminals wrap around purkinje cell
bodies like baskets

Inhibit purkinje cells


GABA
Excited by parallel fibers
Golgi cells

Inhibit granule cells

GABA

Located in granular layer

Excited by parallel fibers
Task

In your team, create a short video (with phones or other devices) explaining how information enters
the cerebellum, how the neurons interact, and how the information is sent out of the cerebellum.

Include:

Mossy fibers and pathways that fall into this category

Climbing fibers and pathway(s) that fall into this category

Granule cells with parallel fibers

Purkinje cells

Corticonuclear and nucleocortical tracts

Excitation vs inhibition (and neurotransmitters)

Today in class: create a plan, write up a script

Post a link to your video on the wiki by Friday Sunday midnight. (part of participation grade – out of 10
points)

Wiki page: Cerebellar Histology Videos (available through term lists and images)
Reciprocal Inhibition

Interneurons inhibit purkinje and granule cells

Only excitation comes from mossy and climbing fibers

Result is inhibitory outputs
Motor learning and the cerebellum

Theory:

When climbing fiber input and parallel fiber input occur at the same time on the
purkinje cell, the post-synaptic purkinje dendrite experiences long-term
depression (LTD)

Beyond this is yet unknown but studying the cerebellar cortex has surfaced
these three hypotheses:

Learning and memory can result from modifications of synaptic transmission.

Synaptic modifications can be triggered by the conversion of neural activity into
intracellular second messengers.

Memories can result from alterations in existing synaptic proteins.
Cerebellum Overview



Functional structure

Vestibulocerebellum

Spinocerebellum

Cerebrocerebellum
Pathways

Afferents

Efferents
Cerebellar histology

Neuron types
Organization of the Course
Spinal Cord
Brainstem/
Cerebellum
Sensory Pathways
Overview and
Development
Other Pieces
of the puzzle
Cerebrum
Cranial Nerves
Motor Pathways
Exam formats



Midterm:

60 MC

Mix of know, understand, apply questions
Tag Test:

15 stations, 5 questions per station = 75 questions

New format: 3-2-1 done
Lab closes end of day Wednesday March 4
Conclusion

Start discussing the rest of the sensory pathways Monday!

Assignment #2 due Monday

Only 3 lectures left until Midterm Exam!!

Finish creating video, post to wiki by Friday midnight!