1. 2017/2018

2. Basal Ganglia & Cerebellum
Phase 1 Revision Session
5th March 2018
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3. Learning objectives Recap basic concepts Recap anatomy
Recap physiology
Questions!
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4. The brain – basic concepts
The brain is a multifunctional system, this system includes:
Structures with specific function
Structures with generic function
Normal processing (physiology) between these structures enables us to function in the world
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5. The brain – basic concepts
Sensory modalities: sight, sound, touch, taste, smell
Cortex – specific structures
INPUT
Thoughts
Cortex & sub-cortical structures – specific & generic
Memories
Emotions
PROCESSING
The World
ACTION SELECTION - HOW DO WE CHOOSE?
Basal Ganglia - GENERIC
PROCESSING
ARE WE DOING IT CORRECTLY?
Cerebellum - GENERIC
PROCESSING
Motor systems: behaviour
Cortex – specific structures
OUTPUT
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6. Basal ganglia – what is it?
Basal ganglia – is a collection of subcortical structures that receive input from all areas of the brain. It’s function is action selection.
WHAT YOU DO
Cerebellum – is a hindbrain structure that coordinates movement, balance, equilibrium, and muscle tone
HOW YOU DO IT
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7. Basal ganglia – anatomy
Corpus Callosum
Caudate
Lateral Ventricle
Putamen
Thalamus
External GP
Internal GP
Internal Capsule
Subthalamic Nuclei
Claustrum
Substantia
Nigra
Amygdala
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8. Basal ganglia – anatomy
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9. Basal ganglia – anatomy
Fornix
Caudate
Lateral medullary lamina
External GP
Claustrum
Internal GP
Hippocampus
Amygdala
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10. Basal ganglia – anatomy
Corpus callosum
Lateral V (A)
Head of Caudate
Putamen
Globus Pallidus
HORIZONTAL PLANE
Thalamus
Caudate Tail
Third ventricle
Posterior horn
Lateral ventricle
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11. Basal ganglia – anatomy
Anterior horn of left ventricle
Corpus Callosum
Head of caudate
Internal capsule (A)
Putamen
Globus Pallidus
Internal capsule (P)
Thalamus
HORIZONTAL PLANE
They can ask you about ventricles on this image as well
Posterior horns, lateral ventricles
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12. Basal ganglia – blood supply
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13. Basal ganglia – anatomy summary
Structures:
Putamen
Caudate (head, body & tail)
Globus pallidus (lateral & medial segments) - always on inside of putamen
Lentiform nucleus (putamen and globus palidus)
SubthaLamic nucleus (always Lateral to red)
Substantia Nigra (line)
Surrounding:
Thalamus
Claustrum
Internal capsule
External capsule - separates claustrum from putamen
Medullary lamina - white matter between putamen and globus pallidus (lateral and medial)
Corona radiata
Corpus callosum
Amygdala
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14. Basal ganglia – physiology
BASAL GANGIA – BASICS
Re-entrant loops
Most of the basal ganglia is GABA inhibitory neurons
Output is inhibitory – this means under baseline conditions the thalamus is inhibited = no action
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15. Basal ganglia – physiology
BASAL GANGIA – PATHWAYS
Direct = activate thalamus = action selection = GO
Indirect = inhibit thalamus= action selection = STOP
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16. Basal ganglia – physiology
BASAL GANGIA – NEUROTRANSMITTERS
Dopamine = GO
GABA = STOP
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17. Basal ganglia – physiology
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18. Basal ganglia – physiology
Alternative diagram for learning direct & indirect pathways - taken from phase1 lecture slides
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19. Basal ganglia – physiology summary
Direct pathway = GO
Indirect pathway = STOP
Dopamine = GO
GABA = STOP
Underactivity of direct pathway or low dopamine = freezing, problems with initiating movement (Parkinson’s)
Underactivity of indirect pathway or low GABA = too much movement, not enough inhibition (Huntington’s)
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20. Basal ganglia – application
Parkinson’s
Problem not enough DA
Symptoms
Reduced movement (shuffle)
Slow to initiate movement
Freezing (doorways, stairs etc)
Treatment
L-dopa
DA agonists
STN lesion
Huntington's
Problem too much DA
Symptoms
Chorea
Overshooting movements
Treatment
DA blockers = neuroleptics (also used for psychosis)
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21. Basal ganglia – application
Several different circuits
Motor circuit
Limbic circuit
Oculomotor circuit
Illnesses associated with Basal Ganglia dysfunction:
Parkinson’s Disease
Huntington’s Disease Motor
Dystonia
Gilles de la Tourette syndrome
Obsessive compulsive disorder Psychiatric
Attention Deficit Hyperactivity Disorder (ADHD) Disorders
Cerebral Palsy Secondary
Wilson Disease Damage
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22. Cerebellum – what does it do?
Function – coordinated voluntary motor movement, balance, equilibrium, and muscle tone
“Continually compares the brains intentions with its actions and makes any necessary modification”
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23. Cerebellum – anatomy
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24. Cerebellum – anatomy
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25. Cerebellum – anatomy Blood supply Superior cerebellar artery
Anterior Inferior
Cerebellar Artery
Posterior Inferior
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26. Cerebellum – anatomy
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27. Cerebellum – functional anatomy
Three peduncles
Superior – output (mainly) – to midbrain then anywhere
Middle – input – from cerebral cortex via midbrain
Inferior – input – from spinocerebellar tracts, vestibulocerebellar tract
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28. Cerebellum – physiology
Re-entrant loops
Structure of origin  cerebellum  structure of origin
Output is excitatory
Three cortical layers, with different cell types
Monitors body position and movement by spinocerebellar input
Monitors cerebral intention via corticopontarcerebellar tract
Matches the last two to give fluid movement
Not just movement – working memory, learning, implicit & explicit memory, language, dyslexia
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29. Cerebellum – application
In cerebellar disease, you may see:
Movements become jerky, erratic and poorly coordinated
Voluntary movement loses fluidity – appears mechanical and robotic
Intention tremor – opposite to PD
Dysarthria – disruption of fine control of speech, slurring
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30. Cerebellum – application
Symptoms may indicate (roughly) where damage is:
Usually ipsilateral to side of damage – eg, if tremor on the right, lesion/ damage on the right of cerebellum
Midline damage – unsteady gait, wide based ataxia, or truncal ataxia, eg damage to vermis
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31. Questions The basal ganglia is responsible for: a)Fine motor control
b)Action selection
c)co-ordinating how we walk
d)Episodic memory 
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32. Questions
Which of the following symptoms is not associated with Parkinson's
Shuffled steps when walking
Muscle rigidity
Intention tremor
No arm swing 
Resting tremor is associated with Parkinsons
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33. Questions
You see a patient in clinic who has left sided violent flinging movements. Most commonly this is caused by a vascular incident affecting the:
a)Left subthalamic nucleus
b)Right subthalamic nucleus
c)Left striatum
d)Right striatum 
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34. Questions
Which of the following is not associated with cerebellar disease:
Resting tremor
Wide based gait
Over-shooting
Nystagmus 
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35. Questions
You see a patient in clinic who has a broad base ataxic gate. You notice that they are mostly unsteady on their right. The most likely location of damage is:
Right striatum
Left cerebellum
Right subthalamic nucleus
Right cerebellum 
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36. Questions
A patient is brought into A&E with a sudden onset of difficulty sitting up or standing. Where is the lesion most likely to be?
Vermis
Flocculus
Striatum
Globus Pallidus 
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