.
Spectrum Center
Phone 1-877-4AUTKID
|
What is Sensory Integration?
|
By Valerie Dejean
Sensory integration is the ability to receive information from the senses,
combine it with prior information, memories, and knowledge, and use that
interpreted information to respond appropriately. In the lingo of Occupational
Therapy we refer to responding appropriately as an “adaptive response.”
Through the process of normal interactions with the environment the individual’s
brain constantly receives sensory input from the body—the ears constantly
hear external and internal sounds, the skin receives constant sensory
messages from the air and clothes, gravity a constant force that the individual
must always orient to, and the eyes (while open) continually adapt to
what is in their line of vision. These sensory messages are, in essence,
“food for the brain:” the brain needs sensory input in order
to function and thrive.
Sensory Registration and Regulation.
The first level of sensory integration is the ability to take in the sensory
information and adjust to it. We refer to this as sensory registration
and self-regulation. Initially, a baby reacts to sensory stimulation in
a total and often defensive manner. For example, a baby’s whole body
will startle to a loud sound or withdraw from an unexpected touch. This
is the early “fight or flight” response that needs to be modified
in order to respond “adaptively.” The baby learns to discriminate
whether the stimuli imposes a danger, or rather is something to be attended
to and enjoyed. As the baby’s brain matures and he is more accurately
able to register and regulate his responses, he enters a state of calm
alertness, from which he can learn from his environment.
Sensory Registration: Reactivity (Thresholds)
A child’s ability to register and regulate his response to sensory
input can be either over-reactive (what we refer to as having low thresholds
for sensory input, as described in the last paragraph), or under-reactive
(the child with high thresholds, who poorly registers sensory input).
This might be the child who you have to call five times before getting
his attention. More often we see a mixed profile; the child, for example,
who seems oblivious to pain yet is bothered by every little noise. It
can sometimes be confusing; for example, a child that has such over-reactivity
(low thresholds) to either touch or sound that they become overwhelmed,
shutting down and consequently presenting as a child who is not reacting
or registering the sensory input. This is important for the therapist
to distinguish, because when therapy starts to “open up” the
sensory systems of such children, they may appear to have swung to the
other extreme. An example of this is a child with such extreme auditory
sensitivities that he shuts down and therefore his auditory system is
not available to discriminate and learn language. During treatment it
is observed that, though the child is now starting to discriminate sounds
and develop language, he appears at the same time to be demonstrating
sound sensitivity. The truth is, he was always sensitive to sound; he
had just closed off this system in order to protect himself. The treatment
did not cause the sound sensitivities, but rather uncovered them as we
“opened up” the auditory sufficiently for this child to attend
to speech sounds. We can now treat the sound sensitivity that caused him
to shut down in the first place. There are many variations of how the
different sensory thresholds interact, and it takes careful study to determine
the patterns that exist in each child.
Sensory Regulation:
Registration and regulation operate on a scale with low thresholds and
high thresholds on either end, and with self-regulation the homeostatic
midpoint. It is in the balance between over-reactivity (low thresholds)
and under-reactivity (high thresholds) that we are well regulated. In
order for a baby, child, or for that matter anyone to be optimally available
for learning, they should be in this “quiet alert” state of
regulation. If one is over-reactive to touch for example and is focused
on the tightness of his belt or the seams in his socks, his sensory system
is not available to discriminate what the teacher is saying. Or a child
may be unavailable for learning because he is so under-reactive to sound
that he drifts off unless the conversation is highly animated. This lack
of balance between low and high thresholds can be observed in a number
of conditions from Autism, PDD, ADD, and auditory processing disorders.
By contrast, just think of the well-rested baby who awakes for his nap
ready to take in the world. This is the starting point of all learning
and it requires the registration and regulation of sensory input.
Sensory Integration
After children are able to register and regulate their responses to sensory
stimuli they must put these separate pieces of information into a meaningful
whole. This is what is referred to as “Sensory Integration.”
The period from birth to eighteen months is a period of massive sensory
integration where babies learn about the physical reality of the world
through their senses. From their sensorimotor experiences they develop
perceptual constructs of the world. The reality that they form based in
large part upon the accuracy of their sensory integration, becomes the
platform from which they interact and communicate with their environment.
For example, when we eat an orange, we have a total sensory experience.
We sense the orange through our eyes (we see it), ears (the sound of the
skin peeling), mouth (the taste), and skin (on our hands and fingers and
in our mouth). We also receive information from less conscious sensory
systems that tell us the exact position of our hand, how wide to open
our mouth, how hard to bite down, how much to move our head to our hand,
etc. Sensory integration allows us to put together all the needed sensory
information to experience eating an orange. If we have misinformation
(poor sensory integration) then we have a faulty picture of the world.
How Does Sensory Integration Relate to My Child?
In a well-functioning brain, messages from the central nervous system
reach their optimal destination in the brain and are responded to. However,
in some individuals, sensory messages are misinterpreted, intensified,
or omitted, which, in turn, does not allow the brain to respond appropriately.
A. Jean Ayres, Occupational Therapist and creator of Sensory Integration
Theory, asserts that the primary building blocks of the central nervous
system are the senses, particularly the special sensesævestibular,
tactile, and proprioceptive. All other skills are complex processes based
on a strong foundation of sensory integration. In Ayres book, Sensory
Integration and the Child, she likens sensory integration disorder to
a large city in which traffic consists of neural impulses. “Good
sensory processing enables all the impulses to flow easily and reach their
destination quickly. Sensory integration dysfunction is a sort of ‘traffic
jam’ in the brain. Some bits of sensory information get ‘tied
up in traffic,’ and certain parts of the brain do not get the sensory
information they need to do their jobs.” (Ayres, Sensory Integration
and the Child, page 51)
How the Senses Interact
Special Senses- The Vestibular System (Somatic Integrator)
Both Dr. Alfred A. Tomatis and Dr. A. Jean Ayres emphasized the importance
of the vestibular system in the inter-relatedness of the senses. The vestibular
system is part of the inner ear and its job is to detect motion and gravity,
and provides us with our sense of balance. It tells us where we are in
space. The vestibular system is a very old sensory system and in evolutionary
terms, was the first sensory system to develop. We needed to know whether
we were up or down before we needed to see, hear, taste, touch or smell.
The vestibular system is the first sensory system to develop in the womb,
and starts to develop when the fetus is only two weeks old. It is fully
formed and starting to function in the womb by 4 and 1/2 months gestation.
Because of this early development the vestibular system has many connections
with the rest of the brain, which develops around it; consequently, it
is believed to provide the foundation for many other functions. When the
influences of vestibular stimuli fail to reach their natural destinations,
they cannot adequately contribute to sensory integration.
One of the functions that is particularly influenced by the vestibular
system is a person’s muscle tone. Muscle tone is the normal level
of muscular tension that exists when the body is at rest yet ready for
action. The vestibular system particularly influences the muscle tone
that helps us resist the influence of gravity. Gravity is always pulling
us to the ground, and if muscle tone is decreased, it is more difficult
to initiate movement or to maintain muscle tension during movement. The
person may appear floppy, not sit up straight, or joints may appear hyper-flexible.
All refined movements of the extremities and head are dependent on an
adequate base of muscle tone to provide postural support. A lack of sufficient
postural support can contribute significantly to difficulties in controlled
movement of our limbs and tongue. This results in difficulties in gross,
fine and oral motor coordination.
Bilateral coordination is another function particularly influenced by
the vestibular system. It provides the opportunity for the two sides of
the body to communicate with each other at the level of the brain stem
via the vestibular nuclei. In this manner it supports the ability of the
body to use both sides in a coordinated manner. We see this initially
when the baby starts to develop equilibrium reactions where one side of
the body responds differently yet in a coordinated manner with the other
side of the body. From this activity the baby develops a sense of where
his center is, and then how to move around it (rotation), and across it
(crossing midline). This awareness provides the foundation for the development
of laterality (sometimes incorrectly referred to as dominance), and for
the specialization of skills on each side of the body. Many of our advanced
human skills, such as language, are dependent on a good foundation of
lateralization and specialization.
The tactile system, our sense of touch, is a sensory system that develops
very early and therefore has the opportunity to influence the developing
brain. Tomatis viewed the skin as part of the vestibular (somatic) integrator
because the tissue that goes on to become the skin in the developing fetus
emerges from the tissue that forms the ear. The tactile system starts
to develop soon after the vestibular system, and it is the only sensory
system that is fully functional at birth. As soon as a baby can move,
he reaches out to the world through his sense of touch. The mouth and
the hands are both very rich in tactile receptors and consequently are
the primary tools the baby uses to explore the world; consequently everything
is put in his mouth. The more accurate the information the baby receives
from his sense of touch, the more accurate his internalized picture of
the world will be.
We call this internalized picture, our body map or body schema. Sensory
information is registered from the body and organized into neuronal models,
which are replications of the environment and our mechanical selves. The
vestibular, tactile, and proprioceptive (information about our body position
from our muscles and joints) systems enable an individual to develop an
understanding of self. We need a “self” and a “non-self”
in order to interact with and understand the world around us. The vestibular
system of the inner ear plays a major role in integrating the information
from these other senses and putting it all together into a meaningful
whole. Dr. A. A. Tomatis described this role as the vestibular integrator.
Good sensory perception is important in the development of accurate neuronal
body models or rather body schema.
The Distance Receptors: Seeing (vision) and Hearing
(audition)
So far in discussing the vestibular integrator we have been talking about
experiences that are either within our body, in contact with our body,
or have to do with how our body relates to the environment. We feel something
when it touches us and we are constantly adjusting our bodies to the force
of gravity. When it comes to vision and hearing we have a different experience.
We see and hear things outside our bodies, and we refer to these sensory
systems as external or distance receptors. We hear or see things from
a distance; it does not have to come in contact with the body. Sensory
information from the visual and auditory systems has to be integrated
with the other senses and this is again accomplished through the vestibular
system.
Visual Integrator
Vision involves the mechanical reception of light, and visual perception
is how we interpret that information. Dr. A. A. Tomatis referred to the
visual integrator as the mechanism for integrating visual information
from the eyes with vestibular information from the body. The vestibular
system has a direct and very fast connection with the eyes. This allows
the individual to quickly detect whether he or the environment is moving.
Have you ever had the experience of sitting on a train stopped in the
station next to another train? As the other train starts to pull out,
you experience a moment of anxiety as your body tells you that you are
motionless, yet your eyes tell you that you are moving. In that instance
you have a sensory mismatch, and it is a good example for how these two
systems are always referencing back and forth between each other.
This vestibular-visual integration is very important developmentally because
a baby starts to attach meaning to his visual environment via this double-checking
with the vestibular system. The baby starts to recognize that it is the
same rattle whether he is lying down or sitting up. He recognizes that
objects are the same no matter which way they are flipped. He starts to
know if he is to the left, right, over, under, in front of, or behind
an object, as well as how these objects relate to him, long before he
knows the words for these orientations. In fact it is hard to learn the
words for these prepositions if you don’t “get” the physical
experience of these positions through good vestibular-visual integration.
The vestibular system provides the foundation for accurately interpreting
information from our visual field. Therefore it has a major impact on
the development of visual perception. People who have been blind since
birth and regain their vision, are completely overwhelmed by what they
see because their brain doesn’t know how to make sense out of it.
Developmentally the visual system depends on the vestibular system to
make sense out of what one sees. Space perception (where we are in space/directionality),
visual perception (spatial orientation of object and symbols such as letters),
and even linguistic concepts of prepositions are end products of sensory
integration that are dependent upon good vestibular-visual integration.
Cochlear (Linguistic) Integrator
Dr. A. A. Tomatis distinguished between hearing, which he described as
the passive reception of sound, and listening, which he described as the
active ability, intention, and desire to focus on sounds. This is similar
to how we distinguished between sight and visual perception. It is possible,
and even likely, to have normal hearing, yet have poor listening. A child
may be able to hear a pin drop from across the room, yet not be able to
attend and listen to what is being said to him.
The vestibular system and the cochlear, the part of the ear that analyses
sound, are anatomically joined and form what we call the inner ear. The
VIII cranial nerve carries sensory information to the brain from both
the balance and hearing parts of the inner ear. The auditory and vestibular
systems lie closely together throughout the nervous system. This allows
for much opportunity for sensory integration between the vestibular and
auditory systems. Sensory integration disorders that involve vestibular
processing can impact the area of speech and language development. Research
has found that therapy aimed to improve the function of the vestibular
system can also result in improved language.
Dr. A. A. Tomatis discovered that faulty sensory information from the
ear could affect vocal output. The concept that the voice can only produce
what the ear can hear was known as the “Tomatis Effect.” When
children mishear sounds, they will misarticulate them also. This can have
a significant impact on speech development.
Faulty sensory information can also affect auditory perception. The auditory
system is required to interpret all the sounds of spoken language and
attach linguistic meaning to them. For example, a dog is able to hear
as well or better than humans; however, the dog’s ear is not able
to separate the speech stream into meaningful words that he can understand.
This requires auditory perception and auditory processing. Together they
provide the foundation for understanding languageæspoken or written.
When we mishear sound through faulty perception and processing, we have
difficulty attaching these sounds to the visual symbols for them (letters).
Because we mishear the sounds we then misspell them. So problems with
reading and writing can be associated with an auditory problem, not just
a visual problem. Although we separate auditory perception and processing
for d
iagnostic reasons, we often refer to difficulties with them
under the single title of “auditory processing disorders.”
Auditory processing disorders are often related to a disorder of processing
within the vestibular system and to difficulties in integrating sensory
information between the vestibular and auditory systems. The auditory
system needs the stable base provided by the vestibular system in order
to process information. Much like the visual system, which has to reference
what it sees through the vestibular system, the auditory system also must
perform a similar reference. Without stability from the vestibular system,
it is difficult for the auditory system to accurately interpret the sound
stream. This topic is covered in more detail in the handout entitled “Auditory
Processing and the Tomatis Method.”
Motor Planning – Praxis
Motor planning is the next level of sensory integration that is imposed
on a foundation of sensory registration and regulation, and sensory integration
and body schema. Praxis is the ability to self-organize. It is the ability
of the brain to conceive, organize, and carry out a sequence of unfamiliar
actions. Dyspraxia means a reduced ability to carry out non-learned movements,
despite adequate motor and conceptual capacity. Praxis is believed to
be a single function involving several basic processes. The first is ideation
or generating an idea of how one might interact with the environment.
Next is the organization of a program of action that includes the correct
sequence and timing of the steps involved. This is the process most accurately
referred to as motor planning. The final process is the execution or the
actual performance of a motor act.
We need praxis in order to develop higher-level skills. It is after the
infant moves beyond the “hard wired” functions of sitting, standing,
walking and babbling that praxis is called upon. These innate functions
occur without praxis. Once the baby moves from sensory motor play (banging
the rattle) to more purposeful play (putting the rattle into a cup), he
starts to rely more on praxis. He needs to have an idea (ideation) of
what he wants to do; he needs to have a plan (organization) of how he
will sequence and time his movements; and finally, he needs to perform
(execute) the action. When we have adequate praxis for successful behavior,
we can adapt effectively to our environment. The better the baby is able
to do this, the more successful, or adaptive, his interactions will be.
It is through successful sensory motor interactions that we develop responses
that lead to further and more advanced interactions with our environment.
All of this, of course, is dependent upon good sensory integration and
a good body schema.
How Can the Spectrum Center Help?
The auditory stimulation and sensory integration techniques offered at
the Spectrum Center can help individuals with Sensory Integration Disorders
by making it easier for them to process and integrate sensory information.
By helping these children reach a more regulated state of calm alertness
they become more available for learning. Children whose systems have been
striving to shut out sensory stimulation become more relaxed and better
able to connect to those around them. Most children with Sensory Integration
Disorder are working much harder than their peers to accomplish the same
things. There is a tremendous experience of relief as things become easier,
leading to an improved sense of self-esteem. Their bodies are now able
to keep up with the things their brains are able to conceptualize. If
you have a child with Sensory Integration Disorder, call the Spectrum
Center to discuss your situation or schedule an initial evaluation.
Copyright 2008