Do you enjoy roundabouts, roller coasters, downhill skiing or parachute jumping? Do you like to relax in a rocking chair, garden swing or hammock? The answers to these questions, regardless of whether you said yes or no, are all linked to the development of our vestibular system.
This is the sensory system that is interconnected with almost every other aspect of our brain. It is considered to be the oldest in evolutionary terms and has its origins in the gills found in ancient fish. During pregnancy, thickenings appear on both sides of the embryo head. These sink into the head to form the hollow spaces which will become the inner ear. They divide into two connected structures.
In the upper part, three hollow, semi-circular tubes or canals form. These are arranged at right angles to each other to become the major part of the vestibular system. The lower part of the ear cavity coils up in a long tube to create the cochlea and becomes the hearing part of the ear.
Gravity
The vestibular system is mostly thought of in terms of balance, but its importance is even more fundamental than that. It links us to our awareness of gravity, which is something we tend to take for granted. But the way we process the sensations of gravity flowing through our nervous system helps provide a reference for all our other sensory experiences.
Our vestibular receptors are the most sensitive of all our sensory organs, because the information they process is vital to our development. The vestibular system is already working in the womb. A foetus responds to movements of the mother's body long before the brain can respond to sight or sound. It is this vestibular activity that provides the foundations for later visual and hearing development.
Every time we move our head, we stimulate the vestibular receptors. This is because gravity shifts the calcium carbonate crystals in our inner ear, which changes the flow of impulses to the vestibular nerve. Jumping makes the crystals go up and down; running and swinging send them in other directions.
Feeling 'gravitational security' is fundamental to our well-being. Think about it for a minute. How scary would it be to not feel anchored to the ground? We need to trust that we are firmly connected to the earth and will not float off into space.
Our vestibular system is what tells us we are secure on the ground, even when we are off it! Our drive for this security is so strong that as babies and young children, we instinctively do the kinds of things that build our vestibular systems. Swinging, climbing, sliding, riding a see-saw or roundabout all provide vestibular stimulation. Whether young or old, we all know the calming influence of a rocking chair or a swing. We instinctively soothe agitated babies with rocking and stimulate them with gentle jiggling or rough and tumble play.
Sensory processing
The vestibular system does an important job in interpreting what we see in relation to ourselves and helping us orientate our body in response. My eyes tell me what is in front of me, but my brain needs to know if it is near or far away. Is it moving, or is it me that is moving? Is something the right way up, or am I upside down?
The brain understands the relationship between object, head and body, because gravity and movement sensations interact with the sensations from all our muscles and joints, and especially those from the eyes and neck.
These muscles play a particularly important role in organising the vestibular system, particularly when it comes to maintaining a 'stable visual field', which is what stops things from fluttering around if we look at them while we are moving.
To compensate for any movement in the head and body, the vestibular system adjusts the neck and eye muscles. This is particularly important in tasks such as reading and copying from a board or screen.
Nystagmus
Nystagmus isn't a word we hear very often, but we all know what it feels like. It refers to the reflex eye muscle contractions that happen after we spin round and round. Observing how long the nystagmus lasts after spinning is currently one of the best ways of measuring how well the vestibulary system is working.
Therapists who are trained in sensory integration will often test the duration of nystagmus when they are working with children who have learning or behavioural difficulties. If the nystagmus is irregular, quickly stops or is not present at all, this would suggest that there is not enough vestibular stimulation or that it is not being processed correctly. If it lasts longer than average, then the system is over-respondng to the stimulation, probably because nothing is inhibiting or overriding it.
Modulation
Modulation is what the brain does to increase or reduce neural activity to keep the activity 'in harmony' with other functions of the nervous system. We should feel relaxed with the gentle stimulus of a rocking chair and aroused by the stimulation of a fast roller coaster.
A well-modulated vestibular system is important for keeping us in a calm, alert state. It helps to keep the level of arousal in our brains balanced. If the modulation is not so well-balanced, however, it can affect us in a variety of ways. Some of these may be fairly insignificant, but some may have a major impact on well-being, spatial awareness and learning development.
Imbalances
An imbalance in modulation, sensory processing or integration may lead to a variety of problems. These include difficulties with:
- following a moving object with the eyes or moving the eyes from one spot to another (can make it hard to catch a ball, or read a line of print)
- bumping into people and things, falling off steps
- protecting yourself when falling (for example, not knowing which way they will fall, forgetting to put your hands out in front of you)
- lining up two things together in space, for example, sticking one thing on to another
- spacing letters when writing
- playing hopscotch or games requiring movement and co-ordination, moving fluidly when dancing
- sitting still on a chair, working at a desk
- using tools
- riding a bike
- spatial awareness, standing too close to others
- anxiety in large open spaces, fear of getting lost.
Language and speech development
Studies have suggested that in some children a lack of vestibular stimulation has a negative effect on language development. One theory is that the language centre in the brain needs constant interaction with other parts of the brain, including the vestibular system.
An understimulated vestibular system therefore will have an impact on language development. It might also play a part in vocalisation and the urge to make sounds. We know that most children will happily shreik and yell when playing a very active or physically stimulating game. Studies have shown that some non-speaking children will increase the number of sounds they make when playing a game with lots of vestibular input.
In her book Sensory Integration and The Child - Understanding Hidden Sensory Challenges, A Jean Ayres suggests it is 'as if the brain needed a certain amount of vestibular input to produce sounds and the movements of daily life did not supply the amount needed in these children'. It is our job to ensure that we provide the right opportunities for playing, both indoors and out, to make up for the vestibular stimulation that our children may be missing out on in their daily lives.
Anne O'Connor is a freelance early years consultant and trainer. Anna Daly is an associate.ecturer at University of Central Lancashire and a freelance community dance artist, specialising in projects and training for early years dance play. She was formerly training and development co-ordinator with Ludus Dance and continues to work with them.
The final article in this series on 16 July will look at the importance of balance in children from birth to five
SUPPORTING CHILDREN'S VESTIBULAR SYSTEMS
We can encourage and support children to develop their vestibular systems by providing them with safe, fun opportunities for movement play.
Under-threes
- Rocking: position the child in your lap, either with your legs crossed or knees bent, gentle rocking, side to side, front and back, falling backwards
- Swaying: in arms close, side to side, forwards and backwards
- Swinging: through legs, low then high, side to side,
- Spinning: Can be done holding close in arms, cradle hold, or facing out, with arms wrapped around the child's tummy, holding out under the arms
- See-saws: child laying on back, forward and backwards tilting, cradled in lap, singing 'Row, row your boat', falling backwards with both sets of legs wriggling in the air
- Rolling: beginning moves on mat, rolling up legs, rolling together on floor, rolling some distance
Over-threes
- Spinning: in different positions - standing, sitting, on knees, on one side, on tummy, with eyes closed, stopping and starting (Note: spinning is stimulating and will cause dizziness, disorientation and over- excitement! These are to be noted, allowed and enjoyed, but do keep a watch for those children for whom it becomes too exciting or disconcerting and reduce the amount of that activity. Always work with a level and intensity that is led by them.)
- Rolling: across a floor space, across the grass, slowly then fast, stopping and starting; can try with eyes closed
- Dancing: indoors and out, with scarves, ribbons, twirling and spinning
- Walking and crawling on moving surface, such as a piece of rippling fabric
- Roundabouts, swings, see-saws and slides along the floor, on long pieces of fabric
- Swaying, rocking:for soothing, calming and focusing attention
Safety and well-being
- Never spin, twirl or swing children excessively or for lengthy periods.
- Always 'check in' with small children for their consent to the activity and to continue or repeat. Watch for the non-verbal signals of body language - tension/relaxation in the body, position and response, smiles, noises of encouragement, responding non-verbally/verbally to the request 'again?' Some children equally enjoy observing others, and their responses, before they want to try. This is all part of their learning process and their risk-assessing.
- Be aware of children who don't seem to get dizzy or like to spin or swing a lot. Observe their development in other areas and seek guidance if concerned.
References and further resources
- Sensory Integration and The Child - Understanding Hidden Sensory Challenges, A Jean Ayres
- Institute of Neuro-Physiological Psychology (INPP), www.INPP.org.uk
- 'Move On' by Mike Jess and Jan McIntyre of the University of Edinburgh (Nursery World, 29 January 2009)
- Sally Goddard Blythe, The Well-Balanced Child: Movement and early learning (Hawthorn Press)
- Penny Greenland, 'Hopping Home Backwards', Jabadao, see www.jabadao.org