The Brain Filling in the Gaps: Why Benign Sensations Can Feel So Powerful

By Dr. Jennifer Gans

The brain relies on several sensory systems to understand and navigate the world. These systems continuously provide information about what is happening both around us and within our bodies.

Our primary sensory channels include:

• Hearing (auditory system)
• Vision (visual system)
• Balance and spatial orientation (vestibular system)
• Touch and body position (somatosensory system)
• Taste
• Smell

Together, these systems allow the brain to build a stable understanding of the environment and our place within it.

Importantly, the brain is not simply receiving these signals. It is constantly interpreting, predicting, and organizing them in order to construct perception.

In clinical terms, the brain is always asking a simple question:

“What should I be sensing right now?”

When sensory input from one of these systems changes, becomes reduced, or becomes ambiguous, the brain does not simply turn that channel off. Instead, it attempts to maintain a coherent picture of the world by adjusting sensitivity, predicting signals, or filling in missing information.

Many puzzling sensory experiences arise from this process. Although the sensations can feel alarming, they are often examples of the brain working exactly as designed.

Understanding this principle can dramatically change how people experience these sensations.

 
Tinnitus: When the Brain Generates Sound

(Auditory System)

Tinnitus is the perception of sound—such as ringing, buzzing, or humming—without an external source.

It begins after a change in the auditory system, typically involving some degree of hearing loss related to noise exposure, aging, or other shifts in auditory input.

When the brain receives less auditory information than it expects, it increases sensitivity in the auditory pathways in an attempt to locate the missing signal.

The sound itself is benign, but if the brain interprets it as dangerous or threatening, attention becomes locked onto it. Increased monitoring makes the sound feel louder and more intrusive.

 
Phantom Limb Sensation: The Brain’s Body Map Remains

(Somatosensory System)

After an amputation, many individuals continue to feel sensations in the missing limb. These sensations may include itching, pressure, movement, or even pain.

This occurs because the brain maintains an internal map of the body within the somatosensory cortex. Even when the limb is gone, the neural representation of that limb remains active.

The brain continues predicting signals from that location and generates sensations accordingly.

 
Charles Bonnet Syndrome: The Visual Brain Creating Images

(Visual System)

In people with significant vision loss, the visual cortex sometimes produces vivid images such as faces, patterns, or scenes.

This condition, known as Charles Bonnet syndrome, occurs when visual input is reduced. With limited incoming information, the brain fills in the gaps by generating its own imagery.

Importantly, individuals with this condition typically understand that the images are not real.

 
Benign Paroxysmal Positional Vertigo (BPPV): When the Brain Tags Motion as a Threat

(Vestibular System)

Benign Paroxysmal Positional Vertigo (BPPV) occurs when tiny calcium crystals from the inner ear shift into the semicircular canals, where they do not belong. This change is unexpected and confusing to a brain that has largely experienced the body as stable and balanced.

When the head changes position, these crystals stimulate the balance sensors and send inaccurate motion signals to the brain. The result is the sudden spinning sensation of vertigo.

The experience can be extremely alarming. A person may feel as if the room is violently spinning or that they are losing control of their balance. Because the sensation is so intense and unfamiliar, the brain often interprets it as a potential threat.

When this happens, the brain’s threat detection system activates. The amygdala signals danger, the autonomic nervous system increases arousal, and the person becomes highly vigilant about head movements that might trigger the sensation again.

Even after the crystals have been repositioned and the mechanical problem has resolved, the brain may continue anticipating danger when the head moves in certain ways. The nervous system remains on alert, scanning for signs that the vertigo might return.

This heightened monitoring can make normal sensations of movement feel unsafe or destabilizing.

In this way, a brief mechanical event can evolve into a learned threat response within the nervous system.

 
Eye Floaters: A Normal Visual Signal the Brain Usually Ignores

(Visual System)

Eye floaters are small clumps of collagen inside the vitreous gel of the eye. As light enters the eye, these particles cast shadows on the retina.

People may see:

• drifting dots
• strands
• cobweb-like shapes

Floaters are extremely common and typically harmless. Most of the time, the brain automatically filters them out through a process called perceptual adaptation.

However, when someone becomes worried about floaters and begins monitoring for them, attention can amplify the perception. The floaters may suddenly seem more noticeable or intrusive.

This pattern closely resembles what happens with tinnitus.

 
A Shared Neurological Pattern

Across these examples, different sensory systems are involved—hearing, vision, balance, and body sensation—but the brain’s response follows a similar pattern.

Sensory System Change in Input Brain Response Auditory
Somatosensory
Visual
Vestibular
Visual Reduced hearing input
Missing limb input
Reduced visual input
Distorted balance signal
Benign retinal shadow Phantom sound (tinnitus)
Phantom sensation
Visual imagery
False motion perception
Heightened visual awareness                        

In each case, the brain is attempting to interpret sensory information that is missing, altered, or ambiguous.

The system itself is not malfunctioning—it is trying to maintain a stable understanding of the body and environment.

 
The Role of Attention and Threat

Across these conditions, the key factor determining distress is not the signal itself but how the brain interprets the signal.

When the brain attaches danger to a sensation, several systems activate:

• the amygdala (threat detection)
• the autonomic nervous system
• heightened attention and monitoring

Attention acts like a spotlight. The more the brain searches for a sensation, the more prominent that sensation appears.

Over time, this can create a loop:

A benign sensation appears
The brain interprets it as threatening
Attention increases
The sensation becomes more noticeable

The signal itself has not changed—the brain has simply assigned it importance.

 
The Power of Understanding

Humans function best when we understand what we are experiencing.

When people learn that a sensation is benign, the nervous system often begins to relax. As fear and monitoring decrease, the brain gradually stops prioritizing the signal.

Attention loosens. The experience becomes less intrusive.

This shift—from fear to understanding—is often the first step in helping the brain recalibrate.

 
From Reaction to Response

The brain is always interpreting signals from the body. Sometimes it gets the interpretation wrong.

When a benign sensation is mistaken for a threat, attention and anxiety can amplify the experience.

But when the brain understands the signal for what it truly is—a normal byproduct of sensory processing—the nervous system can shift from reaction to response.

And when that shift happens, perception often begins to settle on its own.

 
Many people understand tinnitus intellectually, but still find themselves reacting to the sound.
That is where guided practice becomes important.

If it would be helpful to have structured guidance, the full program is available at MindfulTinnitusRelief.com.