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Tuesday, May 10, 2011

The role of hearing and sight in learning disabilities

Something many of us as parents come across when seeking therapy for our children with learning disability is the concept of sensory integration, or more often, sensory integration dysfunction. As humans, we use our sensory systems to gain the information that is necessary for us to respond appropriately to our environment, and of the sensory systems, the two that we use most are the visual and the auditory systems. If either of these systems do not work optimally, and we have not learnt to compensate for their deficit by some other means, we cannot respond optimally. This is more than just being “able to see” or being “able to hear” – in both the visual and the auditory systems, we have two organs (two eyes, two ears), which have to work well not only individually, but also together. Not only must the actual visual and auditory sensory organs work, but the information that they record, has to be dealt with appropriately by our brain, in order for us to make sense of the data.
Take the eyes for instance: if our two eyes do not see equally well, and the sight stimuli obtained through both eyes are not dealt with equally well by the appropriate brain areas, we may end up with double vision. This poses a problem not only in that we cannot see properly, but also results in many more physical and psychological symptoms: we may feel nauseous, have a headache, feel disoriented an extremely irritable, which in turn will cause us to react and respond in negative ways to our environment and people around us. Similarly, when we are not able to hear equally well through both ears, we end up like a radio-station that is not quite tuned-in: at a sub-conscious level, we keep picking up information and losing information, which, again, leaves us feeling disoriented and extremely irritated.
Not only can we have issues when our two eyes or two ears don’t work or don’t work equally well – we also face difficulties when our eyes or ears work too well – when certain frequencies of light or sound are like the proverbial fingernail on the chalk board to us. Many of our kids with “issues” are too sensitive for certain frequencies of light (and particularly fluorescent light) or sound, and when they are exposed to these, they may act out, or may shut-down cognitively, in an attempt to escape the irritating sensory stimulation – either way, they lose out on information that comes through these senses, and consequently, they are again unable to respond appropriately to their environment.
The auditory and balance systems are intertwined in the skull, just behind the ears. Often we find that when a child has issues around one of these systems, there are also issues around the other. The body is truly an interconnected whole: the balance system rules the proprioceptive system, that sensory system that tells the body about where the muscles and joints in the body are located, and which determines muscle tone. If there are therefore issues around the balance system, there are usually issues around the proprioceptive system and muscle tone as well. Muscle tone does not just refer to the base-line tension in the core muscles of the body, but also to that of the small muscles, such as those that facilitate the eyes working together, allowing us to track the words in a line while reading, or to accommodate our focus when altering from far to near vision. Thus, when there are issues around the auditory/balance systems, there are often also issues around binocularity. Thus, immaturity or inbalance in all of these systems, individually or collectively, can impact on our child’s behavior, and thus on their functionality.