20172018 Basal Ganglia Cerebellum Phase 1 Revision Session

2017/2018

Basal Ganglia & Cerebellum Phase 1 Revision Session 5 th March 2018 The Peer Teaching Society is not liable for false or misleading information…

Learning objectives • Recap basic concepts • Recap anatomy • Recap physiology • Questions! The Peer Teaching Society is not liable for false or misleading information…

The brain – basic concepts • The brain is a multifunctional system, this system includes: 1. Structures with specific function 2. Structures with generic function • Normal processing (physiology) between these structures enables us to function in the world The Peer Teaching Society is not liable for false or misleading information…

The brain – basic concepts Cortex – specific structures Sensory modalities : sight, sound, touch, taste, smell INPUT Memories Thoughts. Cortex & sub-cortical structures – Emotions specific & generic PROCESSING Ganglia -- HOW GENERIC ACTIONBasal SELECTION DO WE CHOOSE? PROCESSING ARE WECerebellum DOING IT CORRECTLY? - GENERIC PROCESSING The World Cortex – specific structures Motor systems : behaviour The Peer Teaching Society is not liable for false or misleading information… OUTPUT

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. WHAT selection. YOU DO Cerebellum – is a hindbrain structure that coordinates movement, balance, equilibrium, HOW YOU DO IT and muscle tone The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – anatomy Corpus Callosum Lateral Ventricle Thalamus Internal Capsule Claustrum Amygdala The Peer Teaching Society is not liable for false or misleading information… Caudate Putamen External GP Internal GP Subthalamic Nuclei Substantia Nigra

Basal ganglia – anatomy The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – anatomy Fornix Caudate Lateral medullary lamina External GP Internal GP Amygdala The Peer Teaching Society is not liable for false or misleading information… Claustrum Hippocampus

Basal ganglia – anatomy Corpus callosum Lateral V (A) Head of Caudate Putamen Globus Pallidus Thalamus Caudate Tail Third ventricle Posterior horn Lateral ventricle The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – anatomy Anterior horn of left ventricle Internal capsule (A) Internal capsule (P) Thalamus The Peer Teaching Society is not liable for false or misleading information… Corpus Callosum Head of caudate Putamen Globus Pallidus

Basal ganglia – blood supply The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – anatomy summary • Structures: • Surrounding: • Putamen • Caudate (head, body & tail) • Globus pallidus (lateral & medial segments) - always on inside of putamen • Lentiform nucleus (putamen and globus palidus) • 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 • Subtha. Lamic nucleus (always Lateral to red) • Substantia Nigra (line) The Peer Teaching Society is not liable for false or misleading information…

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 The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – physiology BASAL GANGIA – PATHWAYS • Direct = activate thalamus = action selection = GO • Indirect = inhibit thalamus= action selection = STOP The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – physiology BASAL GANGIA – NEUROTRANSMITTERS • Dopamine = GO • GABA = STOP The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – physiology The Peer Teaching Society is not liable for false or misleading information…

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) The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – application • Parkinson’s • Huntington's Problem not enough DA Symptoms Reduced movement (shuffle) Slow to initiate movement Freezing (doorways, stairs etc) Treatment Problem too much DA Symptoms Chorea Overshooting movements L-dopa • DA blockers = neuroleptics (also used for psychosis) DA agonists STN lesion Treatment The Peer Teaching Society is not liable for false or misleading information…

Basal ganglia – application • Several different circuits – Motor circuit – Limbic circuit – Oculomotor circuit • Illnesses associated with Basal Ganglia dysfunction: – Parkinson’s Disease – Huntington’s Disease – Dystonia – Gilles de la Tourette syndrome Motor – Obsessive compulsive disorder – Attention Deficit Hyperactivity Disorder (ADHD) –Cerebral Palsy –Wilson Disease Secondary Damage The Peer Teaching Society is not liable for false or misleading information… Psychiatric Disorders

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” The Peer Teaching Society is not liable for false or misleading information…

Cerebellum – anatomy The Peer Teaching Society is not liable for false or misleading information…

Cerebellum – anatomy Blood supply • Superior cerebellar artery • Anterior Inferior Cerebellar Artery • Posterior Inferior Cerebellar Artery The Peer Teaching Society is not liable for false or misleading information…

Cerebellum – anatomy The Peer Teaching Society is not liable for false or misleading information…

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 The Peer Teaching Society is not liable for false or misleading information…

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 The Peer Teaching Society is not liable for false or misleading information…

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 The Peer Teaching Society is not liable for false or misleading information…

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 The Peer Teaching Society is not liable for false or misleading information…

Questions The basal ganglia is responsible for: a)Fine motor control b)Action selection c)co-ordinating how we walk d)Episodic memory The Peer Teaching Society is not liable for false or misleading information…

Questions • Which of the following symptoms is not associated with Parkinson's a) Shuffled steps when walking b) Muscle rigidity c) Intention tremor d) No arm swing The Peer Teaching Society is not liable for false or misleading information…

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 The Peer Teaching Society is not liable for false or misleading information…

Questions • Which of the following is not associated with cerebellar disease: a) Resting tremor b) Wide based gait c) Over-shooting d) Nystagmus The Peer Teaching Society is not liable for false or misleading information…

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: a) Right striatum b) Left cerebellum c) Right subthalamic nucleus d) Right cerebellum The Peer Teaching Society is not liable for false or misleading information…

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? a) Vermis b) Flocculus c) Striatum d) Globus Pallidus The Peer Teaching Society is not liable for false or misleading information…