ARIA

How Gait Normally Works

Walking is mostly automatic—your brain's basal ganglia (deep brain structures) generate internal timing signals that sequence your steps without conscious thought. You don't think "lift right foot, swing forward, plant heel, shift weight..."—it just happens.

Basal Ganglia → Internal Rhythm → Motor Cortex → Leg Movement
       ↑                                                    ↓
       └──────────────── Feedback Loop ────────────────────┘

The basal ganglia act as an internal metronome, providing the rhythmic timing that allows walking to feel effortless and automatic.

What Breaks in Parkinson's Disease

Parkinson's disease damages dopamine-producing neurons in the substantia nigra, which connects to the basal ganglia. Without adequate dopamine, the internal rhythm generator fails. The brain literally loses its internal metronome.

Basal Ganglia → ❌ NO SIGNAL → Motor Cortex → Nothing happens
       ↑
       └── Dopamine depleted, rhythm generator offline

Why External Cueing Works: The Neural Bypass

Here's the critical insight: the motor cortex still works perfectly. Only the internal timing mechanism is broken. External cues provide a substitute rhythm that bypasses the damaged basal ganglia entirely, using sensory pathways that remain intact.

                          ┌─────── BYPASS ───────┐
                          ↓                      │
Eyes/Ears → Sensory Cortex → Motor Cortex → Walking!
     │
Laser line / Metronome click

Why the Effect Is Immediate

This isn't therapy that takes weeks of training. The effect is instant because:

1. The motor system is fully intact—it's just waiting for a "go" signal
2. External cues provide that signal through an alternate neural route
3. The moment the cue appears, the brain has something to respond to

ARIA Guide Implementation

ARIA Guide translates this neuroscience into a practical intervention system:

Detection:   Camera sees feet stopped > 2 seconds
     ↓
Visual Cue:  Projects green laser line 18" ahead (stepping target)
     ↓
Audio Cue:   Starts metronome at 100 BPM (rhythm substitute)
     ↓
Patient:    Steps onto line, synchronized to beat
     ↓
System:     Advances laser, maintains rhythm until walking fluid
     ↓
Result:     Walking restored in seconds

The laser and metronome aren't "helping" the damaged system—they're replacing the broken internal signal with an external one that uses pathways that still work perfectly.