cerebellum and pathways. objectives - cerebellum identify the anatomical divisions of the...
Post on 13-Jan-2016
279 Views
Preview:
TRANSCRIPT
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:
https://www.youtube.com/watch?v=5eBwn22Bnio
Ataxia with gross limb movement dysfunction:
https://www.youtube.com/watch?v=qKGicpQLt6M
Ataxic Gait:
https://www.youtube.com/watch?v=FpiEprzObIU
Dysmetria:
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
Rubrospinal tract
Dentate – cerebrocerebellum to thalamus
Planning and control of voluntary movements
All cerebellar efferents synapse in the deep nuclei
The nodulus connects to which nucleus?
A. FastigialB. GloboseC. EmboliformD. Dentate
Fasti
gial
Globose
Embolifo
rm
Dentate
94%
6%0%0%
Your patient has difficulty with fine motor control. Which nucleus would be associated?
A. FastigialB. GloboseC. EmboliformD. Dentate
Fasti
gial
Globose
Embolifo
rm
Dentate
3%
97%
0%0%
Which part of the cerebellum would be associated with the same patient?
A. VestibulocerebellumB. SpinocerebellumC. Cerebrocerebellum
Vestibuloce
rebellu
m
Spinoce
rebell
um
Cerebro
cere
bellum
0%
100%
0%
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?
A. ASCB. CuneocerebellarC. PSCD. Rostrocerebellar
ASC
Cuneocereb
ellar
PSC
Rostroce
rebell
ar
0%
100%
0%0%
The ICP is damaged. Which of the following is TRUE?
A. Ipsilateral sensory info to the cerebellum from the UE is completely gone.
B. Contralateral sensory info to the cerebellum from the LE is completely gone.
C. Ipsilateral sensory info from both limbs is reduced.
D. Contralateral sensory info from both limbs is reduced.
Ipsilate
ral se
nsory
info to th
e c...
Contralat
eral se
nsory
info
to th
e...
Ipsilate
ral se
nsory
info from bot..
.
Contralat
eral se
nsory
info
from ...
19%
0%
81%
0%
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?
A. CeruleocerebellarB. PontocerebellarC. RaphecerebellarD. Reticulocerebellar E. Hypothalamocerebellar
Ceruleo
cere
bellar
Pontoce
rebella
r
Raphecere
bellar
Reticuloce
rebell
ar
Hypothala
moce
rebella
r
5%
44%49%
2%0%
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”Cerebellar cortex (Purkinje cells) → cerebellar nuclei
Cerebellar Nucleocortical Pathway “Fibers”Cerebellar nuclei neurons (Nuclei Cells) → cerebellar cortex
VC = Vermal Cortex
IC = Intermediate CortexLC =
Lateral Cortex
Dentate
Embo
lifo
rm Glo
bose
Fast
igi a
l
White Matter = Arbor Vitae
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
Inf. Peduncle
All of the neurons with somas in the deep cerebellar nuclei exit the cerebellum.
A.TrueB.False
True
False
91%
9%
The corticovestibular tract is from the cerebellar cortex directly to the vestibular nuclei.
A.TrueB.False
True
False
97%
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
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
Cerebellar Efferent Fibers & 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?
A. HypothalamocerebellarB. OlivocerebellarC. RostrospinocerebellarD. Corticovestibular
Hypothala
moce
rebella
r
Olivoce
rebella
r
Rostrosp
inocere
bellar
Cortico
vesti
bular
0% 0%0%0%
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
Which pathways?
Strong but infrequent stimulation from climbing fibers
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
Cerebrum
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!
top related