SENSORY INTEGRATION
By Cindy Hatch-Rasmussen, M.A., OTR/L Therapy
Northwest, P.C. Beaverton, OR 97005
Children and adults with autism,
as well as those with other developmental disabilities, may have
a dysfunctional sensory system. Sometimes one or more senses are
either over- or under-reactive to stimulation. Such sensory
problems may be the underlying reason for such behaviors as
rocking, spinning, and hand-flapping. Although the receptors for
the senses are located in the peripheral nervous system (which includes
everything but the brain and spinal cord), it is believed that the
problem stems from neurological dysfunction in the central nervous
system - the brain. As described by individuals with autism, sensory
integration techniques, such as pressure-touch can facilitate attention
and awareness, and reduce overall arousal. Temple
Grandin, in her descriptive book, Emergence: Labeled Autistic,
relates the distress and relief of her sensory experiences.
Sensory integration is an innate neurobiological
process and refers to the integration and interpretation of sensory
stimulation from the environment by the brain. In contrast, sensory
integrative dysfunction is a disorder in which sensory input is
not integrated or organized appropriately in the brain and may produce
varying degrees of problems in development, information processing,
and behavior. A general theory of sensory integration and treatment
has been developed by Dr. A. Jean Ayres from studies in the neurosciences
and those pertaining to physical development and neuromuscular function.
This theory is presented in this paper.
Sensory integration focuses primarily on three
basic senses - tactile, vestibular, and proprioceptive. Their interconnections
start forming before birth and continue to develop as the person
matures and interacts with his/her environment. The three senses
are not only interconnected but are also connected with other systems
in the brain. Although these three sensory systems are less familiar
than vision and audition, they are critical to our basic survival.
The inter-relationship among these three senses is complex. Basically,
they allow us to experience, interpret, and respond to different
stimuli in our environment. The three sensory systems will be discussed
below.
Tactile System
The tactile system includes nerves under the skin's
surface that send information to the brain. This information includes
light touch, pain, temperature, and pressure. These play an important
role in perceiving the environment as well as protective reactions
for survival.
Dysfunction in the tactile system can be seen
in withdrawing when being touched, refusing to eat certain 'textured'
foods and/or to wear certain types of clothing, complaining about
having one's hair or face washed, avoiding getting one's hands dirty
(i.e., glue, sand, mud, finger-paint), and using one's finger tips
rather than whole hands to manipulate objects. A dysfunctional tactile
system may lead to a misperception of touch and/or pain (hyper-
or hyposensitive) and may lead to self-imposed isolation, general
irritability, distractibility, and hyperactivity.
Tactile defensiveness is a condition in which
an individual is extremely sensitive to light touch. Theoretically,
when the tactile system is immature and working improperly, abnormal
neural signals are sent to the cortex in the brain which can interfere
with other brain processes. This, in turn, causes the brain to be
overly stimulated and may lead to excessive brain activity, which
can neither be turned off nor organized. This type of over-stimulation
in the brain can make it difficult for an individual to organize
one's behavior and concentrate and may lead to a negative emotional
response to touch sensations.
Vestibular System
The vestibular system refers to structures within
the inner ear (the semi-circular canals) that detect movement and
changes in the position of the head. For example, the vestibular
system tells you when your head is upright or tilted (even with
your eyes closed). Dysfunction within this system may manifest itself
in two different ways. Some children may be hypersensitive to vestibular
stimulation and have fearful reactions to ordinary movement activities
(e.g., swings, slides, ramps, inclines). They may also have trouble
learning to climb or descend stairs or hills; and they may be apprehensive
walking or crawling on uneven or unstable surfaces. As a result,
they seem fearful in space. In general, these children appear clumsy.
On the other extreme, the child may actively seek very intense sensory
experiences such as excessive body whirling, jumping, and/or spinning.
This type of child demonstrates signs of a hypo-reactive vestibular
system; that is, they are trying continuously to stimulate their
vestibular systems.
Proprioceptive System
The proprioceptive system refers to components
of muscles, joints, and tendons that provide a person with a subconscious
awareness of body position. When proprioception is functioning efficiently,
an individual's body position is automatically adjusted in different
situations; for example, the proprioceptive system is responsible
for providing the body with the necessary signals to allow us to
sit properly in a chair and to step off a curb smoothly. It also
allows us to manipulate objects using fine motor movements, such
as writing with a pencil, using a spoon to drink soup, and buttoning
one's shirt.
Some common signs of proprioceptive dysfunction
are clumsiness, a tendency to fall, a lack of awareness of body
position in space, odd body posturing, minimal crawling when young,
difficulty manipulating small objects (buttons, snaps), eating in
a sloppy manner, and resistance to new motor movement activities.
Another dimension of proprioception is praxis
or motor planning. This is the ability to plan and execute different
motor tasks. In order for this system to work properly, it must
rely on obtaining accurate information from the sensory systems
and then organizing and interpreting this information efficiently
and effectively.
Implications
In general, dysfunction within these three systems
manifests itself in many ways. A child may be over- or under-responsive
to sensory input; activity level may be either unusually high or
unusually low; a child may be in constant motion or fatigue easily.
In addition, some children may fluctuate between these extremes.
Gross and/or fine motor coordination problems are also common when
these three systems are dysfunctional and may result in speech/language
delays and in academic under-achievement. Behaviorally, the child
may become impulsive, easily distractible, and show a general lack
of planning. Some children may also have difficulty adjusting to
new situations and may react with frustration, aggression, or withdrawal.
Evaluation and treatment of basic sensory integrative
processes is performed by occupational therapists and/or physical
therapists. The therapist's general goals are to:
• provide the child with sensory information which
helps organize the central nervous system
• assist the child in inhibiting and/or modulating
sensory information
• assist the child in processing a more organized
response to sensory stimuli.
For further information, contact: Sensory Integration
International, P.O. Box 9013, Torrance, CA 90508, USA
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Visit their site for more useful resources
Click here for the full
range of Asperger's and autism fact sheets at www.autism-help.org
Sensory issues are explored further in the Sensory
Problems fact sheet
Click here
to read an interview with Lorna Jean King on Sensory Integration
Therapy |
