Higher Functions: Movement Planning😊

Higher Functions: Movement Planning

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  • SNc/SNpc → Substantia Nigra
  • STN → Subthalamic nucleus
  • GPi → Inhibitory
  • GPe → Excitatory

Cerebellum

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Parts & Functions

Part
Function
Cerebrocerebellum (Lateral)
• Planning and timing of movement
• Lesion: I/L Limb ataxia
Spinocerebellum (Intermediate + Vermis)
• Smoothening and coordination of movement
• Lesion: Truncal ataxia/ Proximal limb
Vestibulocerebellum (Flocculonodular)
• Vestibular reflex, balance, and posture
• If affected:
↳ Alcoholic gait and Nystagmus

Cerebellar lesions

Cerebellar Lesions – DANISH

  • D: Dysarthria, Dysmetria, Decomposition of movement
  • A: Truncal Ataxia (drunken gait)
    • Wide based stance
  • N: Nystagmus
    • Kinetic /Intention tremor (during voluntary movement)
      • Seen with activity.
      • Absent at rest.
    • Titubation 
      • Tremors of head
  • I: Incoordination / Intention tremor
  • S: Slurring or scanning speech
  • H: Hypotonia

Others

  • Past pointing (Finger-nose test)
  • Pendular knee jerk
  • Dysdiadochokinesia:
    • Inability to perform alternating supination and pronation movements.
  • Rebound phenomenon:
    • Unable to stop the movement.

Note:

  • No sensory deficit
  • No abnormality at rest

Note

Posterior column defect
  • Stomping gait
  • Inability to walk with eyes closed

Basal Ganglia

Anatomy functions of Basal Ganglia

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Subthalmic nuclei → motor function
Subthalmic nuclei → motor function
• Basal ganglia/ Gangliocapsular bleed • Presentation - Dense hemiplegia
• Basal ganglia/ Gangliocapsular bleed
• Presentation - Dense hemiplegia
  • Frontal horn of lateral ventricle adjacent to caudate nucleus.
  • Thalamus is adjacent to 3rd ventricle
  • Then medially to laterally
    • Internal capsule → Lentiform nucleus → Insula
  • White area indicates acute hemorrhage
    • M/c: Putamen
    • Most common cause: HTN.
    • Management: Conservative

Functions of Basal Ganglia

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Step
Function
Structure
1
Idea for movement
Cortical association area
2
Planning and programming
of voluntary motor movement
Basal ganglia & Lateral cerebellum
(cerebrocerebellum)
3
Prepare for execution
Premotor cortex & Motor cortex
4
Feedback to premotor/motor cortex
Basal ganglia & Cerebellum
5
Initiate movement
Motor cortex → α motor neurons
6
Receives initiation info
(parallel input)

Continuous sensory info during movement
Spinocerebellum
7
Skill and procedural memory
Striatum
8
Cognitive functions
Prefrontal cortex
↳ Motivation
↳ Emotional regulation
↳ Decision making
↳ Memory

Disorders of Basal Ganglia

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Disorder
Lesion Site / Pathophysiology
Type
Key Features
Parkinsonism
Dopamine deficiency in substantia nigra → affects striatum
Mainly hypokinetic
Bradykinesia, akinesia, tremor (hyperkinetic)
Hemiballismus
Subthalamic nucleus
Hyperkinetic
(thala de thazhe (subthalamus) bale (hemibalismus))
Huntington disease → Chorea
Striatum damage - GABA
(Putamen + Caudate)
Hyperkinetic
Choru (chorea) Puttu (putamen) Curry (caudate)
Dystonia
Direct pathway damage → thalamocortical overactivity
Hyperkinetic
Sustained involuntary contractions
Athetosis
Globus pallidus
Hyperkinetic
Slow, writhing movements

(writing (writhing movement) on globe (globus pallidus))
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  • SNc → Substantia Nigra
  • Norepinephrine locked in ICU → Locus ceruleus
  • ↑↑ Dopamine activity → Madly (Schizophrenia) hunting ()
  • ↓↓ GABA → ↓↓ inhibitions → during anxiety () and hunting ()
  • Norad → patients becomes anxious ()
  • ↓↓ AcH → Alzheimer's, Huntintons (↑↑ in Park)
Condition
NT
Location
Alzheimer's disease
↓↓ Acetyl choline
Nucleus basalis of Meynert
Parkinson's disease
Dopamine ↓↓
↳ bradykinesia

↑↑ Acetyl choline
Nigrostriatal

Mnemonic: Mayil (Meynert) Basil (Basalis) nu Achingum (Acetylcholine) Alzheimersum vannu
Addiction
Dopamine
Nucleus accumbens
Mesolimbic

Location
↳ Medial Frontal area
↳ Ventral tegmental area
ALS
Glutamate

Amy → Glue
Hippocampus,
Subthalamic nucleus → Memory

A-delta fibres → Fast pain
Huntington's chorea
Dopamine ↑↑
GABA ↓↓
AcH ↓↓
Loss of GABA in striatum
Tetanospasmin
↳ spastic paralysis
↳ Presynaptic
GABA 
Inhibits release of GABA
Strychnine
↳ spastic paralysis
↳ Postsynaptic
Glycine

Stry → Gly
Inhibits release of glycine.
Mesocortical
ã…¤
Prefrontal cortex
↳ Motivation
↳ Emotional regulation
↳ Decision making
↳ Memory
Tuberoinfundibular
Dopamine
• Hypothalamus
• Physiologic inhibition of prolactin

IDENTIFY

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1-caudate nucleus
2-globus pallidus
3-putamen
4-external capsule
 
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Transverse section of midbrain

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At the level of Superior colliculus
At the level of Inferior colliculus
• III cranial nerve orginates
• 3 lemnisci
• Red nucleus
• 4 lemniscus
• 4th CN originates
↳ Has internal decussation
↳ Only CN with dorsal origin