"Seven senses? Like that movie with Bruce Willis where the kid can see dead people?" Sensory Processing and our Seven Senses

I’ve mentioned sensory processing (also known as sensory integration) a few times in my past blog entries. Non-OT readers of this blog have probably been wondering exactly what I’m talking about. It’s a part of my everyday language as a pediatric OT, and it’s actually part of every single person’s everyday neurological process, but outside my field it’s not something commonly known about or talked about. So here’s my “sensory processing in a nutshell” explanation.

Those not familiar with the term “sensory processing” may be able to deduce that it has something to do with how the brain processes information from one’s senses. However, what you may not know is that people actually have SEVEN senses that we receive input from. (And no, the sixth sense is not being able to see dead people!) There are the 5 “basic” senses that most people are familiar with: touch (tactile sense), sound (auditory sense), sight (visual sense), smell (olfactory sense) and taste (gustatory sense). However, there are also two other systems from which receive input and contribute to sensory processing: the vestibular system (movement sense) and the proprioceptive system (position sense).

The first "secret sense" that is very much a part of your sensory system but few people are aware of is your movement sense. The vestibular system. Vestibular receptors are structures within the inner ear. When the head changes position, these structures register this information and send it to the brain to process it to help determine the body’s position in relation to earth’s gravity. This system is how people know when they are in motion.

The OT in this picture is providing vestibular input to a child on a therapy swing

Proprioception, "the position sense" is the brain’s unconscious ability to determine where all one’s body parts are without having to look at them, and where the body is in relation to other objects or people without having to touch them. Receptors in our muscles, joints, and connective tissue (ligaments and tendons) receive propioceptive input and send it to the brain to process. It is how the brain interprets sensory messages about the position, force, and direction of one's body and its parts. Gravity acts on these receptions even when we are not moving.

Sensory integration/processing is a normal neurological process that every person’s neurological system does, all the time. Every person’s nervous system/brain is designed to receive information from the world around us through sights, sounds, touch, tastes, smells, movement and gravity. The body receives this input, and the brain perceives and interprets the information. The brain then “tells” the body what to do based on how it is interpreting the sensory information. When people experience a challenging level of sensory simulation and successfully respond to it, they develop an “adaptive response.”

Sensory processing problems occur when some aspect of sensory processing does not function effectively, and the person may experience stress throughout the course of everyday occupations. This is because the neurological processes should be automatic and accurate (the processes of taking in sensory input, interpreting it, and generating an appropriate adaptive response) are not.

Even with properly functioning sensory processing, everyone has sensory preferences and dislikes. For example, loving or hating rollercoasters, spicy foods, certain musical dynamics, scents or colors. That is normal. However, for children who have sensory processing disorder/sensory integration dysfunction, or “sensory issues,” the way they experience the world is so much more than sensory preferences or dislikes.

When there is a breakdown in these neurological processes, it can manifest in several different ways (and every child is different!) It can present as a trouble with sensory modulation, which causes the child’s responses to sensory input to be out of proportion to the actual experience. This can present as over-, or under-responding to sensory stimuli, seeking sensory stimulation, or a mix depending on the type of input and the situation. Another effect of sensory processing difficulties can be motor output that is disorganized as a result of incorrect processing of sensory information. The child may be dyspraxic (unable to plan and execute motor movements necessary for everyday tasks), and appear accident-prone, clumsy, physically awkward and struggle with both gross and fine motor skills.  Another manifestation can be difficulty perceiving the salient qualities of sensory input, and/or struggling to differentiate between sources of sensory stimuli, such as judging how much force to use on different objects. However, the most common manifestation is disordered modulation and the seeking or avoiding of types of sensory input due to the inability to effectively process that input.

Sensory Processing Disorder (SPD) will be recognized for the first time in the upcoming DSM-V (the Diagnostic and Statistical Manual of Mental Disorders). SPD is becoming more widely recognized in the pediatric community, with many books shedding light on this issue hitting the shelves for both professionals and as self-help for parents of children experiencing these problems. These books include “The Out of Sync Child” and “The Out of Sync Child Has Fun” both by Carol Stock Kranowitz, “Raising a Sensory Smart Child” by Lindsey Biel and Nancy Peske, and “Sensational Kids” by Lucy Jane Miller and Doris A. Fuller. These are all books I’ve read, loved, and recommended to parents, and parents have reported back to me about finding hope and understanding in these books.

In addition to children with SPD, most  children diagnosed on the autism spectrum also have significant sensory processing problems. In a study of children with autism spectrum disorders, 94% of the 200 children studied having significant sensory issues*. In the mental health realm, sensory processing issues are inherent to schizophrenia. A number of other disabilities include problems with sensory processing and/or are co-morbid with sensory processing disorder.

So what do occupational therapists have to do with sensory processing? OTs deal with sensory processing because when a child has issues with sensory processing, it affects his or her ability to play, work, learn, have appropriate social interactions, dress, eat, and function within their family or school environment. Anything affecting a child’s ability to engage in his or her childhood occupations (self-help, eating, functioning in his or her family unit, and functioning in school) OTs can be involved. Now you may be wondering what is it that OTs do for these “sensory kids”? OTs use the Sensory Integration Frame of Reference (affectionately known as SI) developed by A. Jean Ayres to guide treatment. First, when beginning treatment, OTs meet the child where he or she is at. Therapists provide the child with opportunities to get a lot of the input he or she is seeking while monitoring it to help the child stay regulated, and do not force input that he or she is defensive of. Therapists help the child feel safe, calm, and comfortable in his or her own body and in the environment. We as pediatric OTs create an environment that facilitates exploration of different sensory experiences that is both fun for the child and therapeutic. OTs use a variety of swings and suspended equipment, textures, fabrics, toys, games, places to crash, things to climb, music, and other equipment to create a sensory environment that is both comfortable and challenging for each child. We use knowledge of sensory processing and how the brain perceives the different types of sensory input to create experiences that will affect his or her brain’s ability to process and regulate sensory information and generate adaptive responses.

Not the gym I work in but a very good example of the equipment used in an OT "sensory clinic" much like where I work

Hope that clarifies a bit. Not wanting to make this entry too long, I will save specific examples of sensory processing disorder with the kids I treat for a later blog :)

*(Greenspan & Wieder, 2000)