Vestibular Sense

Try to imagine pushing a wheelbarrow across Niagara Falls on a tightrope. Scary, right? Jean François Gravelet, also known as The Great Blondin, did this in 1860. The senses, including the kinesthetic, visual, and vestibular senses, played an essential role in this incredible act. This section will focus on the vestibular sense - the balance sense!

• What is vestibular sense?
• Where is the vestibular sense located?
• What behavior would be difficult without our vestibular sense?
• How does the vestibular sense work?
• What is vestibular sense in autism?

Vestibular Sense Psychology Definition

The vestibular sense is our sense of how our bodies move and where they are in space, which facilitates our sense of balance. Our vestibular system is in our inner ear, which also has vestibular receptors. Vestibular sensations give us a sense of balance and help in maintaining body posture.

As babies, we use our senses and body movements to learn about our environment. As we age, we still use our senses to help us navigate our daily lives. Vestibular sensations are one of the ways our senses help us move easily.

Fig. 1 - A child walking into the living room requires vestibular sense to balance and navigate the area.

We need vestibular sense to engage in different activities that require our feet off the ground, such as:

• Riding a bike, swing, or rollercoaster
• Going down a slide
• Jumping on a trampoline
• Climbing a ladder

When walking on sand or a wet floor, your vestibular sense helps you stay upright and stable.

When processing vestibular sensations is difficult, such as in people with autism, they may over-respond, under-respond, or actively seek movements. In other words, the vestibular sense in autism involves the difficulty of the vestibular system to provide information about motion, balance, position, and force of gravity.

This situation can lead to:

• Over-response to movements. A child may avoid activities that trigger vestibular sensations, such as swinging, riding a seesaw, or going on a rollercoaster.
• Under-response to movements. A child may appear clumsy and uncoordinated. He may struggle to keep upright and become fatigued quickly from different activities.
• Actively seeking movement. A child may excessively engage in activities that promote vestibular sensations, such as jumping or spinning.

Vestibular Sense Organs

The inner ear is home to our body's vestibular system, which includes these sensory organs: three semicircular canals and two vestibular sacs (utricle and saccule). The semicircular canals and vestibular sacs help our vestibular sense tell us when our head tilts or turns.

Fig. 2 - The vestibular system is located within the inner ear¹.

Semicircular Canals

This pretzel-shaped sensory organ consists of three canals, and each canal resembles a pretzel loop. All canals contain fluid (endolymph) lined with hair-like receptors (cilia), cells that receive sensory information. Semicircular canals specifically sense head movements.

The first canal detects up-and-down head movement, such as when you nod your head up and down.

The second canal detects movement from side to side, such as when you shake your head from side to side.

The third canal detects tilting motions, such as tilting your head left and right.

Vestibular Sac

This pair of vestibular sacs, namely the utricle and saccule, also contains fluid lined with hair cells. These hair cells have tiny calcium crystals called otoliths (ear rocks). The vestibular sac senses fast and slow movements, such as when riding an elevator or speeding up your car.

When you move your head, your inner ear moves along with it, causing fluid movement in your inner ear and stimulating the hair cells in the semicircular canals and vestibular sacs. These cells send a message to your cerebellum (the key brain area in the vestibular sense) via the vestibular nerve. Then to your other organs, such as the eyes and muscles, allowing you to detect your body orientation and keep your balance.

The vestibulo-ocular reflex (VOR) is an example of this, which involves interaction between our vestibular system and eye muscles, allowing us to focus our eyes on a specific point even with head movements.

To test this reflex, you can do this simple exercise. Using your right hand, give yourself a thumbs-up. Look at your thumbnail while maintaining your thumb at arm's length. Then, nod your head up and down repeatedly. If you have a functioning VOR, you can see your thumbnail clearly even when you move your head.

Vestibular Sense: Example

Just as the vestibular system is crucial to a tightrope walker, artistic cyclist, or figure skater, we also use it in daily activities that require balance, maintaining position, and other activities where our feet leave the ground.

• Walking: The vestibular sense enables a baby to take its first steps. They learn to walk as they begin to feel balanced. Children have a very sensitive vestibular system but respond more slowly to movement as they age. Walking on a curb or another uneven surface is another example.
• Driving: While driving on bumpy roads, your vestibular system allows you to focus on the horizon as your car moves up and down.
• Dancing: Ballet dancers can also maintain stability as they spin and rotate their bodies with one leg and the other off the ground by fixing their gaze on a particular spot in the distance.
• Climbing stairs: The vestibular sense helps older adults keep their balance while moving up and down the stairs and not fall off.
• Maintaining our posture: Our bodies can remain steady in actions that require good postural control, such as throwing a ball without losing our footing or reaching over the table without falling out of our chairs.
• Spatial awareness: We can sense whether we're on or off the ground or walking on a flat or a slope. The vestibular system gives us awareness of the direction of our movement.

Vestibular Sense vs Kinesthetic Sense

We know that both the vestibular and kinesthetic senses relate to body position and movement. These two sensory systems combine with visual information to allow us to maintain our balance. But how are they different?

The vestibular sense is concerned with our sense of balance, while the kinesthetic sense is concerned with our awareness of the movements of various body parts.

Fig. 3 - Playing sports uses both vestibular and kinesthetic senses.

The receptors of the vestibular system respond to fluid movement in the inner ear due to changes in body or head position. Kinesthetic receptors, on the other hand, detect changes in the movement and position of a body part through the receptors located in the joints, tendons, and muscles.

Both kinesthetic and vestibular systems communicate with the cerebellum via the vestibular nerve and spinal column.

Vestibular Sense and Balance

Balance involves complex interactions between the brain, vestibular system, vision, and kinesthetic senses. But, how does the vestibular system contribute to our balance?

When you move, the different sensory organs of the vestibular system sense your body position relative to gravity. The vestibular system communicates this sensory information to your cerebellum, also called the "little brain," located at the back of your skull, which is the brain region responsible for movement, balance, and posture. Balance occurs as the cerebellum uses this information combined with sensory information from your eyes (vision), muscles, and joints (kinesthetic sense).