Understanding sensory integration and processing
Sensory Processing is a term that refers to the way the nervous system receives sensory messages and turns them into responses. All of us are constantly managing sensory messages. Sight, sound, touch, taste, smell- the five familiar senses, but we also constantly manage sensory information from the proprioceptive and vestibular senses which give us our perceptions of speed, movement, pressure on joints and muscles, and the position of our bodies. These messages are organised into the ´right´ behavioural and physiological responses. Sensory processing difficulties exist when sensory signals do not get organised into appropriate responses and a child's routines and activities are disrupted as a result.
Sensory Modulation is a dynamic Central Nervous System Process that is subject to the ebb and flow of continual input over multiple channels (Lane 2002). On a behavioural level, modulation is, ´the ability to regulate and organise reactions to sensory input in a graded and adaptive manner´(McIntosh 1999).
In order for the behaviours to be understood under the light of the model, the term neurological threshold needs to be explained. Simply put, it refers to the amount of stimuli required for brain cells to respond. A high threshold means that it would take a lot of stimuli to meet the threshold and fire a response, whereas low threshold means that it takes very little stimuli to meet the threshold and fire a response.
Sensory Processing difficulties are sub-divided into 3 different areas; Sensory Modulation, Sensory Discrimination and Sensory-based motor disorder.
Our sensory systems
Vestibular → receptors located in the inner ear provide information related to head position and movement, and respond to gravity and motion, especially change in direction. Vestibular processing is responsible for functions such as balance, equilibrium responses, muscle tone, coordination of eye and head movements and ability to use both sides of your body together. Vestibular input also regulates your arousal level and plays a critical role in helping to maintain a calm and regulated state.
Proprioceptive → receptors located in muscles and joints provide information on body and limb position along with orientation in space. Proprioceptive processing determines the amount of force and or pressure needed to accurately perform gross and fine motor tasks. It makes us aware of where our body is in space and enables us to move in a smooth coordinated manner.
Tactile → refers to the sensory messages received through our skin. Tactile information is a basis for learning about the external objects as well as the condition of our body.
Auditory → this system provides information about sound in the environment.
Visual → this system provides information about how we visually see our environment; orienting one's body to space and perceiving positions of objects in relation to oneself and to other objects, discriminating dominant features in different objects, distinguishing an object from its background, visual memory.
Olfactory → this is our sense of smell.
Gustatory → this is our sense of taste.
Appropriate processing and organisation of these senses are essential for children to adaptively respond to their environment. When a child has difficulty with processing and organising the sensory information, they may demonstrate difficulties with gross motor, fine motor, speech/language, perceptual, self-help skills as well as demonstrate difficulties with attention and behaviour.