The basal ganglia are a group of subcortical nuclei that function with the cerebral cortex to control motor activity. They receive input from the cortex and send output back to the cortex. The putamen circuit executes patterns of motor activity like writing or throwing a baseball. Lesions in different parts of the basal ganglia circuit cause movement disorders like chorea or hemiballismus. The caudate circuit controls sequences of motor patterns through cognition. Parkinson's disease results from dopamine depletion in the basal ganglia and causes tremors, rigidity, bradykinesia, and other motor and non-motor symptoms. Treatment involves dopamine replacement therapy and other drugs or surgery.

1. BASAL GANGLIA

2. Basal Ganglia (Nuclei) Group of deep, interrelated subcortical N Accessory motor system that Functions usually not by itself but in close association with cerebral cortex & corticospinal motor control system Most input signals from: cerebral cortex Most output signals back to: cerebral cortex

3. Anatomy Caudate Putamen Globus pallidus Substantia nigra Subthalamic nucleus

4. Anatomy Overview

5. Anatomy

6. The Putamen Circuit – Executing Patterns of Motor Activity

7. The Putamen Circuit - Functions Putamen circuit + cerebral cortex Controls complex patterns of motor activity Writing, Cutting paper with scissors, Hammering nails Shooting a basketball through a hoop, passing a football, Throwing a baseball Most aspects of vocalization Controlled movements of the eyes And virtually any other skilled movements

8. The Putamen Circuit - Lesions Globus Pallidus: Spontaneous, continuous writhing movements of a hand, an arm, the neck, or the face – Athetosis Subthalamus: Sudden flailing movements of an entire limb – Hemiballismus Putamen: Flicking movements in hands, face, & other parts of body – Chorea Substantia Nigra: Common and extremely severe disease of rigidity , akinesia , and tremors - Parkinson ’ s disease

9. The Caudate Circuit – Cognitive Control of Sequences of Motor Patterns Cognition Most motor actions occur as a consequence of cognition Caudate nucleus is pivotol

10. The Caudate Circuit Timing and Scaling of movements

12. BG Circuit - Neurotransmitters

13. ? What was common between Yasir Arafat , Muhammad Ali & Adolph Hitler ?

14. Parkinson’s Disease Degenerative disorder of basal ganglia Dopamine depletion results from: Degeneration dopamine nigrostriatal system Antipsychotic drugs that block dopamine receptors Toxic reaction to a chemical agent The Northern California drug dealer!* Severe carbon monoxide poisoning

15. Parkinson’s Disease – Clinical Tremor (involuntary tremor) Affects distal segments of limbs (hands and feet; head, neck, face, lips, tongue; or jaw) Characterized by rhythmic, alternating flexion & contraction movements (4-6 beats/minute) Disappears during voluntary movement Start unilateral- spread bilateral Rigidity Resistance to movement of both flexors & extensors throughout the full range of motion Most evident during passive joint movement involves jerky, cogwheel-type movements requiring considerable energy Start unilateral- spread bilateral

16. Parkinson’s Disease – Clinical Bradykinesia (slowness of movement) Movements: Are slow to initiate & perform Difficult to stop Are stiff & staccato in character instead of smooth While walking: Walking and turning en bloc is difficult Freezing spells take small, shuffling steps without swinging arms Posture: Lean forward to maintain center of gravity Loss of postural reflexes – fall (often backward) Masked face: Emotional & voluntary facial movements become limited Loss of blinking reflex Failure to express emotion Throat: Tongue, palate, and throat muscles – rigid Drooling common Speech: slow and monotonous, without modulation and poorly articulated

17. Parkinson’s Disease – Clinical Advanced Parkinsonian features: Dementia (similar to Alzheimer’s disease) Falls Fluctuations in motor function Neuropsychiatric disorders Sleep disorders

20. Parkinson’s Disease – Treatment Nonpharmacologic Group support Education Daily exercise, adequate nutrition Botulism toxin injections Pharmacologic Antiparkinson drugs act by: Increasing functional ability of underactive dopaminergic system Increase dopamine levels (levodopa) Augment release of dopamine (amantadine) Function as dopamine agonists (bromocriptine) Inhibit metabolic breakdown of dopamine (selegiline) Reducing excessive influence of excitatory cholinergic neurons Anticholinergic drugs

21. Parkinson’s Disease – Treatment Surgical Thalamotomy or pallidectomy performed using stereotactic surgery

22. Overall Motor Control