Parkinson's Disease as Dopaminergic Wrong Attractor: Substantia Nigra Depletion, Motor Circuit Displacement, and the Progressive Landscape of Lewy Body Pathology

We apply the Displacement Framework to Parkinson's Disease (PD), formalizing it as W_PD — a progressive dopaminergic wrong attractor driven by substantia nigra pars compacta (SNpc) depletion through Lewy body (α-synuclein aggregate) pathology. The motor ground state S⁰_motor is defined across five dimensions: normal SNpc dopamine output, balanced basal ganglia direct/indirect pathway activity, fluid voluntary movement initiation, absence of resting tremor, and normal gait and posture.

W_PD is maintained by progressive dopaminergic depletion that hyperactivates the indirect pathway and suppresses the direct pathway, generating the TRAP symptom cluster (tremor, rigidity, akinesia, postural instability). Nine formal propositions cover: S⁰_motor definition with basal ganglia circuit mechanics (P1), W_PD as Lewy body wrong attractor with α-synuclein prion-like propagation (P2), the 80% threshold — SNpc must lose ~80% dopaminergic neurons before clinical motor symptoms emerge, representing the neuroprotective intervention window (P3), resting tremor as W_PD oscillatory signature at 4-6 Hz (P4), Braak staging as Φ accumulation trajectory from olfactory/dorsal vagal nuclei (Stage 1) to cortex (Stage 6) (P5), the non-motor prodrome — anosmia, REM sleep behavior disorder, and constipation as D(ξ_nonmotor) preceding motor symptoms by 5-20 years (P6), L-DOPA/carbidopa as dopamine replacement return path (P7), deep brain stimulation of subthalamic nucleus as circuit-level landscape modification (P8), and exercise as neuroprotective return path through BDNF upregulation (P9).

Genetic PD forms (SNCA, LRRK2, PINK1) are formalized as landscape pre-distortion.