Table 1.

Maladies associated with the PPN in PD, the source and affected brain components, as well as its consequence/ indications.

Malady type	Source	Brain components affected	Consequence/ Indications
LOCOMOTOR
Akinesia/bradykinesia/hypokinesia	Overactive GABAergic BG output	MCx, thalamus, BG, PPN, SC, MLR	Decreases in velocity and amount of movement
Hypertonus	Increases in BG inhibition Increases in PPN inhibition Decreases in cortical PPN excitation Direct-indirect pathway imbalance via increased SNr inhibition	MCx, BG, PPN	Increased muscle tone
Dystonia	Diminution or instability of BG GABAergic outputs to the PPN	BG (SNr, Gpi), PPN	Central and spontaneous fluctuations in muscle tone, posture, or locomotion
Gait disturbances/ failure	Excessive MLR inhibition via SNr-GABAergic output Cortical excitation of brainstem reticular formation Decreases in cortical stimulation of the brainstem reticular formation Inactivity of the PMC Dysfunction of BG-BS system Direct-indirect pathway imbalance	MLR MCx, brainstem Primary MCx SNr, PPN, MLR, SC	Uncontrolled gait Limited movement Freezing of gait, increases in stance phases in locomotor cycles and decreases in locomotor velocity
COGNITIVE
Impaired attention and memory learning	PPN lesions	PPN	Inability to concentrate, unable to retain memory
Motivation and compulsion	PPN lesions, impaired brain mechanisms and neural circuitry formation involved in reward processing	NAcc, VTA, PPN	Obsessive compulsive disorder
SLEEP
REMS	Decreases in BG dopaminergic activity	SNr, GPi, DRN, LDT, PPN	REMS behavior disorder