Basal ganglia/nucleus Parts Function of the basal ganglia Direct = - - PowerPoint PPT Presentation

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basal ganglia nucleus parts function of the basal ganglia
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Basal ganglia/nucleus Parts Function of the basal ganglia Direct = - - PowerPoint PPT Presentation

Nov 24, 2022 46 likes •481 views

Basal ganglia/nucleus Parts Function of the basal ganglia Direct = Dark grey Red Blue Light grey Indirect = Dark grey Green Blue Light grey Text Fig. 26-9 Medium spiny neuron projections Neurons of the basal ganglia

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Basal ganglia/nucleus

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Parts

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Function of the basal ganglia

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Direct = Dark grey – Red – Blue – Light grey Indirect = Dark grey – Green – Blue – Light grey

Text Fig. 26-9

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Medium spiny neuron projections

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Neurons of the basal ganglia

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Connections and circuits

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Functional loops

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Motor Loop

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Text Fig. 26-10A,B

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Text Fig. 26-10C,D

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Text Fig. 26-10C,D

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Modulators (associated nuclei)

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  • Subthalamic Nucleus ?????
  • Nigral Complex (Dopamine)
  • Pedunculo-pontine nucleus (Acetylcholine)

Modulators (associated nuclei)

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  • Subthalamic Nucleus ?????
  • Nigral Complex (Dopamine)
  • Pedunculo-pontine nucleus (Acetylcholine)

Modulators (associated nuclei)

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Nigral modulation

R

glu DA Direct transmission

EPSP

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glu DA Almost No direct effect of DA

Direct transmission vs. modulation

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R

enhanced

  • r diminished

response Modulation glu DA D1-Rs in the direct pathway: Excitatory effect on the pathway, hence Increase cortical activity

Direct transmission vs. modulation

Striatal medium spiny neuron

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R

enhanced

  • r diminished

response Modulation glu DA

Direct transmission vs. modulation

D2-Rs in the indirect pathway: Inhibitory effect on the pathway, hence Increase cortical activity

Striatal medium spiny neuron

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Direct and Indirect Pathways (Including the Substantia Nigra

Text Fig. 26-14A,B

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  • Subthalamic Nucleus ?????
  • Nigral Complex (Dopamine)
  • Pedunculo-pontine nucleus (Acetylcholine)

Modulators (associated nuclei)

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R

enhanced

  • r diminished

response Modulation glu Ach M4-Rs in the direct pathway:

1) Inhibitory, hence decrease

cortical activation

Direct transmission vs. modulation

Striatal medium spiny neuron

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R

enhanced

  • r diminished

response Modulation glu

Direct transmission vs. modulation

M1-Rs in the indirect pathway: excitatory, hence Decrease cortical activity

Striatal medium spiny neuron

Ach

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Hypokinetic disorders

  • insufficient direct pathway output
  • excess indirect pathway output

Hyperkinetic disorders

  • excess direct pathway output
  • insufficient indirect pathway output

Motor behavior is determined by the balance between direct/indirect striatal outputs

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Parkinson’s disease

Pathophysiology

Primary: loss of nigrostriatal DA projection SNc Striatum

Michael J. Fox Muhammad Ali

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Parkinson’s disease

Treatment

Deep brain stimulation subthalamic nucleus (STN)/ globus pallidus interna (GPi) high frequency stimulation inactivates the STN or GPi. Dopamine Acetylcholine

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Hypokinetic disorders

  • insufficient direct pathway output
  • excess indirect pathway output

Hyperkinetic disorders

  • excess direct pathway output
  • insufficient indirect pathway output

Motor behavior is determined by the balance between direct/indirect striatal outputs

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Involuntary (unwanted) movements

  • Chorea
  • Ballismus
  • Dystonia
  • Athetosis

Hyperkinetic symptoms

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Hyperkinetic disorders: choreatic syndromes

  • 1. Huntington’s Chorea
  • 2. Sydenham Chorea
  • 3. Dystonia
  • 4. Tardive dyskinesia
  • 5. DOPA-induced dyskinesia
  • 6. Hemiballismus
  • 7. Tourette’s syndrome
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Huntington’s disease

Pathophysiology

  • Atrophy of striatum
  • Loss of striatal neurons
  • Neuropathological sequence
  • start , rostral and medial then caudal and

lateral

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Huntington’s disease

Symptoms

Early motor signs

  • chorea (brief,

involuntary movements)

  • later have dystonia

episodes Choreatic gait Dystonic movements

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Hyperkinetic disorders:

  • 1. Huntington’s Chorea
  • 2. Sydenham Chorea
  • 3. Dystonia
  • 4. Tardive dyskinesia
  • 5. DOPA-induced dyskinesia
  • 6. Hemiballismus
  • 7. Tourette’s syndrome
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Hyperkinetic disorders: choreatic syndromes

Huntington’s disease Dystonia Tardive dyskinesia DOPA-induced dyskinesia Hemiballismus Tourette’s syndrome

Cervical dystonia After botulinum toxin

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Hyperkinetic disorders: choreatic syndromes

Huntington’s disease Dystonia Tardive dyskinesia DOPA-induced dyskinesia Hemiballismus – unilateral STN stroke Tourette’s syndrome

After treatment with the D2-R blocker sulpiride

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Hyperkinetic disorders:

  • 1. Huntington’s Chorea
  • 2. Sydenham Chorea
  • 3. Dystonia
  • 4. Tardive dyskinesia
  • 5. DOPA-induced dyskinesia
  • 6. Hemiballismus
  • 7. Tourette’s syndrome
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Hyperkinetic disorders:

  • 1. Huntington’s Chorea
  • 2. Sydenham Chorea
  • 3. Dystonia
  • 4. Tardive dyskinesia
  • 5. LDOPA-induced dyskinesia
  • 6. Hemiballismus
  • 7. Tourette’s syndrome
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Hyperkinetic disorders:

  • 1. Huntington’s Chorea
  • 2. Sydenham Chorea
  • 3. Dystonia
  • 4. Tardive dyskinesia
  • 5. LDOPA-induced dyskinesia
  • 6. Hemiballismus
  • 7. Tourette’s syndrome
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Hyperkinetic disorders:

Tourette’s syndrome

https://www.youtube.com/watch?v=e8HtTb0Vk_o https://www.youtube.com/watch?v=jYRa-fpNonY