Basal Ganglia

CAUDATE  NU

PUTAMEN

GLOBUS PALLIDUS

AMYGDALA

CLAUSTRUM

Blood Supply: Corpus Striatum

Medial

&

 Lateral Striate

Arteries

Blood Supply: Subthalamus 

Posteromedial

Arteries

Blood Supply: Substantia Nigra

Posteromedial

Posterolateral

Ant. Choroidal

Arteries

Motor System: Functions

Planning, Initiation, Facilitation, and

Suppression of Movement

CAUDATE NU

PUTAMEN

GLOBUS PALLIDUS

Limbic System: Functions

Mood,  Motivation,  and  Behavior

NU ACCUMBENS

AMYGDALA

Basal Ganglia Mechanisms and Concepts

  lower motor neurons

  Basal ganglia connect with

  the cerebral cortex on same

  (ipsilateral) side

  ganglia neurons fire

  continually during movement

  ganglia neurons fire prior to

  the upper motor neuron

  mediated via striatum and

  subthalamus

  mediated via striatum and

  substantia nigra (dopamine)

Input to Basal Ganglia

INPUT :Planning & Initiation

 of movement (Glutamate)

Striatum: Mechanisms and Concepts

Striatum: sporadically active.

Interneurons (Ach) modulate

and suppress dopamine activity.

Striatal Output:

I = Indirect Pathway suppresses

movement (GABA-Enkephalin)

D = Direct Pathway facilitates

      movement (GABA-

      Substance P)

Dopamine from substantia nigra ALWAYS

Dopamine from substantia nigra ALWAYS facilitates movement.

It is excitatory to the striatal Direct Pathway and is inhibitory to the Indirect Pathway.

Basal Ganglia Output

Basal Ganglia Output:

Medial Globus Pallidus

Inhibits(GABA) movement

and is tonically active.

During movement 20% of

neurons decrease activity;

80% increase activity to inhibit

competing movements.

OUTPUT: Excitation to

upper motor neurons

allowing movement

     (Glutamate)

BASAL GANGLIA

 &

 CEREBELLAR

CIRCUITRY  SIMILARITIES

  Cerebellum have any direct

  connections with Lower Motor Neurons. 

 - Both Basal Ganglia & Cerebellum

   receive fibers from widespread areas

   of cortex

   converge on Motor areas of Frontal

   Lobe  via Dorsal Thalamus to

   modulate the Upper Motor Neuron

   well as Feedback  systems

  same Upper Motor Neurons

   systems

HYPOKINESIA

HYPOKINESIA  =  Movement ↓ Tone↑

Akinesia  =  Absence of movement; Impaired initiation of movement or stopping movement

Bradykinesia  =  Reduced velocity and amplitude of movement

DOPAMINE   <  GABA + ACETYLCHOLINE

Hyperkinesia 

Hyperkinesia= Movement ↑ Tone ↓

*Note:  Involuntary movements are ARAS dependent and disappear when asleep.

Unilateral lesions affect  Contralateral side of body.

DOPAMINE   >  GABA + ACETYLCHOLINE

Disorders: Involuntary Movements

TREMOR   =    Rhythmic oscillatory movement

ATHETOID  =  Slow, twisting movements of distal muscles

CHOREIFORM  =  Brisk, fast, dance-like

BALLISTIC  =  Fast, flailing (flinging) and rotatory movement of proximal extremities

DYSTONIA  =  Sustained or repetitive muscular contraction or cramping often resulting in joint distortions

* TIC  =  Brief, abrupt spasmodic twitching and other stereotyped movements.

* AKATHISIA  =   Movements acted out by an inner feeling for the need  to move.  Often induced by antipsychotic medications

 MYOCLONUS  =  Lightning like intermittent muscle jerks (origin unknown)

Parkinson's Disease

PARKINSONISM  or Paralysis Agitans (“The Shaking Palsy”) is characterized by akinesia,

bradykinesia, festination, resting tremor, rigidity, impaired postural (vestibular)  reflexes as

well as cognitive and emotional disorders.

 AKINESIA = difficulty initiating or stopping movement

 BRADYKINESIA = slow movement with decreased amplitude and velocity

 TREMOR AT REST = Tremor of 3 to 5 CPS involving fingers, wrist, lips, or head RIGIDITY =  Resistance to stretch throughout the range of motion characterized by hypertonia of all muscles, agonists and antagonists, throughout the body.  

  returns and the sequence is repeated like a cogwheel ratchet. Tremor is superimposed on

  rigidity.