Each of us has a sensory system. Put succinctly, it is how our brain and nervous system work together to interpret and act on what is going on around us. We respond to our external environment through the familiar five senses of sight, hearing, taste, smell, and touch, as well as through three lesser-known senses: movement (vestibular), body awareness (proprioception), and skin sensitivity (tactile).
Sensory integration is the process by which the brain takes incoming information, organizes it, and interprets it so that we can respond to it appropriately. For example, through the tactile sense, we learn fine motor movements such as those that enable us to button clothing and develop discrimination skills. It can also serve as a protective mechanism when we get too close to something dangerous like a heat source. The vestibular sense receives information about where a person is in space. Changes in head position, and body movement through space, are received through this sense, which coordinates the movements of the eyes, head, and body. Proprioceptive input is responsible for the muscle control in movement. It allows us to manipulate objects, jump, run, and walk. When all the senses are coordinated, they provide a foundation along with cognitive abilities for perceptual skills and motor planning. Motor planning is the ability to organize sensory information in order to plan and carry out the appropriate sequence of movement required to complete a task. For example, motor planning would be observed in a child, who acting on his desire to play with a ball, knows how to judge where the ball is in space and where to position his arms to catch it.
At times of stress, exhaustion, hunger, or illness, we all demonstrate difficulties in sensory integration, but for the most part, the nervous system is able to process and interpret meaningfully without difficulties. For some children, however, sensory integration does not develop as efficiently as it should. How and why this occurs may be linked to hereditary factors, prenatal development, or premature birth (which can be factors in both domestic and international adoptions). Lack of stimulation in early years of development, such as a limited repertoire of foods and textures in the diet or limited opportunity for movement and exploration, plays a large part in contributing to sensory integration problems. Therefore, children who have lived for a time in orphanages often display some sensory integration difficulties, which are usually transitional, if appropriate intervention is provided.
Depending on the severity of the symptoms, effects can be transitory or long term. However, since the nervous system in children is so malleable, intervention often significantly improves or ameliorates the problem. As children matures neurologically (both on their own and/or with intervention), positive changes in behavior will occur as well as achievement in the developmental milestones. Learning to accommodate to the changing environment or to a particular area of weakness is also possible as a child learns and grows.