This post is intended to provide important background information regarding Sensory Integration and to help understand underlying pathophysiology of Sensory Processing Disorders.
Sensory Modulation Disorders
Sensory Modulation refers to the ability to match behaviors to the intensity of the stimuli. Three identified subtypes of Sensory Modulation disorders include:
- Sensory Over-Responsivity (SOR): A child prone to over-responsivity may be irritated by sounds, touch, or imposed movement.
- Sensory Under-Responsivity (SUR): A child prone to under-responsivity may not be focused/seem aware of surroundings, for example not hear his or her name being called or may not be able to maintain an upright, seated position in his or her chair.
- Sensory Seeking (SS): A child prone to seeking/craving may be constantly in motion, opting to jump, talk loudly, or mouth objects.
- High Arousal: High activity (i.e. tendency to attack, demonstrate aggressive behaviors)
- High Arousal: Low activity (i.e. tendency to avoid, withdraw or “shut-down”)
- Low Arousal: High activity (i.e. tendency to seek sensory input, running/crashing)
- Low Arousal: Low Activity (i.e. tendency towards passivity)
Sensory Discrimination Disorders
Sensory Discrimination is the ability to distinguish between sensory signals. A child with Sensory Discrimination Disorder may have various difficulties, such as not being able to hear what is said if there is background noise, not being able to feel a pencil among the objects in his or her desk, or not being able to distinguish whether he or she is in motion, the speed of movement, or which direction he or she is moving in.
Sensory-Based Motor Disorders
Motor disorders often have a sensory basis, reflecting an underlying deficit within the proprioceptive and/or vestibular systems. The vestibular system provides information on balance and movement, as it responds to changes in gravitational pull. The proprioceptive system provides information from muscles, ligaments and joints, regarding the relational positions of different parts of the body, and force exerted.
A child with dyspraxia will have difficulty in planning and grading motor activities. He or she may appear clumsy or avoid daily activities that involve multiple steps. The child with postural disorder may slump at his or her school desk or have difficulties coordinating both eyes, both hands or upper and lower body movements.
Sensory processing problems may stem from a poor “physical sense of self” (touch and proprioception) which leads to a compromised body system, requiring the brain and the body to focus on keeping the self together (more brainstem function). This means the child is NOT ready for higher cortical functioning until the basic, subcortical needs are met. For example, a child that is not in a regulated state, (seeking crashing, in motion, eyes darting), is not ready for a fine motor activity or to perform a basic speech and language task.
By observing and assessing the child’s current presentation of physical state we can determine what type of input would help to regulate and provide each child with the tools needed to focus on higher level tasks for skill acquisition and development.
Children with sensory integration disorders often operate primarily at the brain stem level. They may display primitive instincts for survival and protection, demonstrating fight or flight, causing the body to function on “auto pilot”, thereby limiting function and learning. It is so important for children to feel safe, secure, comfortable and confident in every learning environment, because we cannot learn when we are stressed.
Specific somatosensory input from the vestibular, proprioceptive and tactile systems often help the individual with sensory processing difficulties get “ready” to process information, allowing for true sensory integration, and help to limit feelings of being bombarded by external stimuli. Different sensations provide different responses, and are typically specific to the individual. However, in general, think of what is calming, or organizing to a child, as well as to you. Rhythmic, linear movement, swaddling, and mouthing all provide intense input to the somatosensory system. In addition, when we are upset or anxious, a big hug can often make us feel better, as can a good massage, and/or exercise. These aforementioned activities incorporate tactile, proprioceptive and vestibular sensations. These sensations are believed to facilitate the release of specific chemicals, which have neuromodulatory effects on the central nervous system, meaning that they can either facilitate or inhibit neural signals.
Ayres, A. Jean, and Jeff Robbins. Sensory integration and the child: Understanding hidden sensory challenges. Western Psychological Services, 2005.
Bogdashina, Olga. Sensory perceptual issues in autism and asperger syndrome: Different sensory experiences-different perceptual worlds. Jessica Kingsley Publishers, 2016.
Parham, L. Diane, et al. Fidelity in sensory integration intervention research. The American Journal of Occupational Therapy 61.2 (2007): 216.
Siegelbaum, Steven A., and A. J. Hudspeth. Principles of neural science. Eds. Eric R. Kandel, James H. Schwartz, and Thomas M. Jessell. Vol. 4. New York: McGraw-hill, 2000.
Vargas, Sadako, and Gregory Camilli. A meta-analysis of research on sensory integration treatment. American Journal of Occupational Therapy; 53.2 (1999): 189-198.