12/12/2025
⭐️ **WHEN THE BRAIN LOSES ITS MAP:
The “Where” & “What” Pathways, The Superior Colliculus, Midbrain Concussion & Post-Trauma Vision**
One of the most overlooked consequences of concussion isn’t just blurry vision…
…it’s the breakdown of how the brain maps the world and how the world maps onto you.
The visual system doesn’t just help you see.
It helps you predict, locate, orient, stabilize, and navigate.
After a concussion, these pathways can become desynchronized—leading to dizziness, headaches, light sensitivity, motion intolerance, anxiety, spatial disorientation, and difficulty reading or focusing.
At The Functional Neurology Center, we evaluate and rehabilitate the entire visual-vestibular-midbrain network—because recovery depends on restoring the brain’s internal GPS.
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🔵 THE TWO MAJOR VISUAL STREAMS: OUR INTERNAL “WHAT” & “WHERE” SYSTEMS
The visual cortex branches into two powerful processing highways:
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🔷 1. The WHERE Pathway — The Dorsal Visual Stream
(Occipital → Parietal → Midbrain)
This pathway answers:
• Where am I?
• Where is the object?
• How fast is it moving?
• How do I move my body relative to it?
It integrates:
• Motion detection (V5/MT)
• Spatial awareness
• Balance & postural control
• Eye–head coordination
• Saccades and pursuit eye movements
This system relies heavily on the midbrain, superior colliculus, parietal cortex, and vestibular system.
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🔶 2. The WHAT Pathway — The Ventral Visual Stream
(Occipital → Temporal)
This pathway answers:
• What is it?
• What color?
• What shape?
• Is this familiar? (facial & object recognition)
It integrates:
• Detailed recognition
• Reading & tracking
• Object identification
• Emotional responses through the temporal lobe & limbic system
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🧠 WHAT HAPPENS AFTER A CONCUSSION?
A concussion can shear, slow, or desynchronize these pathways.
It’s not uncommon to see:
❌ Dorsal stream dysfunction (WHERE pathway):
• Feeling “off” or disoriented in space
• Motion sensitivity
• Difficulty with saccades
• Over- or under-shooting targets
• Losing your place when reading
• Balance or gait instability
• Trouble filtering visual motion (e.g., busy environments, scrolling screens)
❌ Ventral stream dysfunction (WHAT pathway):
• Difficulty recognizing faces quickly
• Reading fatigue
• Visual distortions
• Slow object recognition
• Sensory overload
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🎯 **THE SUPERIOR COLLICULUS:
Your Brainstem’s Motion-Mapping Command Center**
The superior colliculus (SC) sits in the midbrain, and acts like a primitive but extremely fast “orienting machine.”
Its jobs include:
• Mapping where things are in space
• Directing saccades (fast eye movements)
• Integrating visual + auditory + sensory cues
• Generating rapid head/neck orientation
• Filtering threats vs non-threats
• Helping you stabilize posture and gaze
After concussion, the SC often becomes:
• Hyperactive (light sensitivity, startle responses, panic-like reactions)
• Hypoactive (poor target acquisition, slowed saccades, delayed orientation)
• Disorganized (spatial disorientation, dizziness, driving difficulty)
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⚠️ THE MIDBRAIN & MIDBRAIN CONCUSSION
The midbrain is the crossroads of:
• Vision
• Vestibular reflexes
• Eye movements
• Hearing
• Pain modulation
• Autonomic integration
When the midbrain is injured or inflamed, patients may experience:
• Difficulty mapping where they are in space
• Problems generating accurate saccades
• Trouble stabilizing vision with head movement
• Sluggish convergence or vergence
• Fight-or-flight activation and increased anxiety
• Light/noise sensitivity
This is why midbrain injuries don’t just cause visual issues—
they create global sensory dysfunction that impacts mood, balance, and cognition.
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👁🗺 SACCADE MAPPING — THE BRAIN’S INTERNAL RADAR
Saccades allow you to rapidly shift between targets.
Healthy saccades require:
• A clean superior colliculus map
• Balanced frontal eye fields
• Accurate parietal spatial awareness
• Stable vestibular input
• Timely cerebellar calibration
After concussion, saccades may become:
• Overshooting
• Undershooting
• Slow
• Jerky
• Fatiguing
This affects reading, balance, depth perception, and your ability to feel grounded.
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🧩 HOW WE ASSESS & REHABILITATE THESE SYSTEMS AT THE FNC
We use a multi-system evaluation to determine which visual pathways and midbrain networks are disrupted:
• VNG, vHIT, Retitrack & saccadometry
• Oculomotor testing (saccades, pursuits, OKN, fixation stability)
• Cervical & proprioceptive integration testing
• Vestibular reflex mapping
• Midline & spatial awareness tests
• Convergence/vergence assessments
• Motion & gaze stabilization tasks
Based on these findings, we create a customized rehabilitation plan that may include:
• Targeted dorsal stream rehabilitation
• Saccadic retraining and spatial remapping
• Superior colliculus & midbrain modulation
• Vestibular recalibration
• Cervical proprioceptive integration
• Optokinetic and gaze-holding exercises
• Primitive reflex & postural restoration
• Ciatrix CSF flow modulation
• ARPwave neuromodulation to trigeminal pathways
• Light, laser, PEMF, and recovery-based sensory therapies
Our goal is to restore clarity, stability, motion tolerance, and spatial confidence—
so patients not only see again…
but navigate the world with ease.
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💬 BOTTOM LINE: Vision Is Not Just Sight — It Is Spatial Existence
When the WHAT and WHERE pathways, superior colliculus, and midbrain are disrupted, the world can feel unsafe, unpredictable, and visually overwhelming.
With targeted, neuroscience-based rehabilitation, the brain can rebuild its maps, restore orientation, and regain control.
👉 If you or a loved one is still struggling after a concussion, dizziness, or visual motion intolerance, there is hope, and we can help.
The Functional Neurology Center
Advanced Brain-Based Rehabilitation — Minnesota & Beyond
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TheFNC.com
612 223 8590
