The somatosensory system uses nerve endings and receptors embedded in skin to detect tactile (touch) information about body contact with the environment and with objects, and uses endings and receptors embedded in muscles, tendons, ligaments, and joint surfaces to receive proprioceptive information about body position in space and body segment positions relative to each other.
This important sensory information is then processed in the spinal cord, the cerebellum and basal ganglia, and the primary somatosensory area of the brain cortex where it is used to modulate both body balance and the precise execution of purposeful movements. [1,2]
The somatosensory system operates on a mature level in preschoolers.  There is a progressive improvement in balance function with age. Somatosensory function is intact and unchanged throughout the ages of 5 to 17 years, while there are significant increases in vestibular function with age and visual contribution with height.  While visual input prevails as a primary balance mechanism in normal children and adults, the contribution of somatosensory input to balance maintenance is significant, and does not change through most of adulthood. 
Effects of aging on sensory functions. One third of adults over the age of 65 years fall each year. Current laboratory and clinical evidence suggests that aging results in:
- Varying declines in the shape and physiologic function of assorted sensory structures
- Losses of distal large myelinated sensory fibers and receptors
- Impaired distal lower-extremity proprioception, vibration and discriminative touch sensation
- Impaired balance.
Further research is needed to clarify the relationship between sensory impairment and balance.
Sensory Modulation Dysfunction (SMD)
Formerly known as “sensory processing disorder” (SPD) and “sensory integration dysfunction”, SMD is a condition in which sensory signals are not successfully organized into appropriate responses. SMD can occur in isolation or as part of another disorder, such as one of the autism spectrum disorders or the attention deficit hyperactivity disorders.
A recent study found specific structural brain abnormalities in the sensory processing regions of the brain in children displaying clinical evidence of sensory modulation or processing issues.
SMD may affect one or more senses. Similar to many illnesses, the symptoms of SPD exist on a spectrum. One person with SMD may over-respond to sensation and find clothing, physical contact, light, sound, food, or other sensory input to be unbearable. Another might show little or no reaction to stimulation, even pain or extreme hot and cold. If the processing of sensory messages from the muscles and joints is impaired or delayed, posture and coordination of motor skills can be affected. Still other children exhibit an appetite for sensation that is in perpetual overdrive.
Find more information at: www.spdstar.org/.
TheraTogs’ Role in Improving Sensory Modulation
Proceeding upon the assumption that optimum motor output requires optimum sensory input, and in keeping with Dr. AJ Ayers’ principles of Sensory Integration therapy, for the child whose appetite for sensation is in perpetual overdrive, TheraTogs undergarments (made of specialized elasticized fabric and cozy foam lining) provide the wearer with maximum adjustability for delivering customized compression and optimum comfort. The typical result is a calming effect and an increase in attention to tasks and people.
The mechanism at work in this response seems to be one of satisfying the desire for somatosensory input in an organized and comfortable way. The increase in body awareness afforded by the garments appears to clarify the child’s impression of his or her body perimeter, and perhaps to alleviate the need to continually seek that information.
The addition of strapping that improves functioning postural alignment adds correct sensory information from the joint mechanoreceptors – a stimulus to coactivate the postural muscles – while further improving the biomechanical and kinesiological aspects of postural control and motor function.
Tip: If the child responds adversely to wearing the foam-lined garments against the skin, we suggest applying a heat- and moisture-wicking undershirt first.
- Steindl R, Kunz K, et al. 2006. Effect of age and sex on maturation of sensory systems and balance control. Dev Med Child Neurol. 48(6):477.
- Cumberworth VL, Patel NN, Rogers W, Kenyon GS. 2007. The maturation of balance in children.J Laryngol Otol. 2007 May;121(5):449.
- Pedalini ME1, Cruz OL, et al.2009. Sensory organization test in elderly patients with and without vestibular dysfunction. Acta Otolaryngol. 129(9):962.
- Shaffer SW, Harrison AL. 2007. Aging of the somatosensory system: a translational perspective. Phys Ther. 87(2): 193. Review.
- Owen JP, Marco EJ, Desai S, et al. 2013. Abnormal white matter microstructure in children with sensory processing disorders. Neuroimage Clin. 23;2: 844.