An experiment was done where people's vision was completely removed for 5 days. In just a couple of days the brain had rewired itself to make other senses heightened (fingers for reading Braille, hearing to distinguish small differences in sound, as well as vestibular to detect small differences in movement). When the blindfolds were removed, the people had a hard time seeing and judging where they were in space...but after a couple of days, their brains adjusted once more and were back to the way they were before the experiment.
The conclusion was that, even though we have names for areas of our brains, such as "visual cortex" and "auditory cortex" those areas aren't reserved specifically for that function. But, in the visual cortex vision is the path of least resistance to receive that input, so those are the neuronal connections that are made and solidified. So, when that visual path is blocked, other connections are made for other senses, and that explains why Sadie's hearing is so sensitive, as well as her vestibular.
Here's a little background about Sadie and movement (vestibular). We discovered real early that to calm our baby she needed to move. And I'm not talking rock her in a rocking chair or put a vibrating mat in her crib, I'm talking brain rattling movement. If she was being held and bounced, you weren't doing it right unless your legs burned. If she was in the bouncy chair it had to be violent; we called it the hurricane. And in the chillout chair, her head needs to be rocking back and forth for the movement to truly be calming. It takes violent, extreme movement to stimulate that vestibular system. But, on the other hand, Sadie is also very sensitive to movement when she's sleeping. With most babies, once they're asleep you can get them out of a car seat and carry them all the way upstairs and put them to bed (I know, I've seen it), not Sadie. If Sadie falls asleep in my arms, sometimes a big sigh will wake her up. When we put her to bed at night, one of us usually lays down with her in the bed. Once she's asleep, the big challenge is to get out of that bed with as minimal movement possible so as not to wake her (maybe she needs a Tempurpedic memory foam mattress like we have!). So after reading about this vision experiment and how it effected the brain, I started thinking about how this knowledge applies to my own child.
Sadie is visually impaired, but her impairment is directly related to damage in her occipital lobe, which is where your visual cortex is. Because of this injury I am not sure how much of her visual cortex is functioning, obviously some since her vision is not completely gone. However, as her vision improves, I'm not sure another part of her brain hasn't taken that over. But, let's say she isnt' using her visual cortex to its full capacity, are her other senses taking over? Does this still happen even when your visual block is brain related (as opposed to eye related)? And if this is indeed the case, can we correct her extreme vestibular and hearing by blocking something else out?
The lesson in the chapter of the book I read, which included the previously mentioned experiment, was that if you want one part of the brain to be super-charged, you have to block its helper. This theory seems to be recurring in the book, when helping people regain strength, movement, and coordination after an accident, there was noted progress once that path of least resistance was blocked. So, if after a stroke, someone had lost the use of the left side of their body, the right hand would be inhibited to encourage the use of the left hand, therefore strengthening and reconnecting those neurons in their brain that had been damaged or destroyed. I have lots of other theories about how we can use this kind of technique to help Sadie's physical strength, but I'll save that for another post.
So, here's my hypothesis: Since Sadie is not fully using whatever visual cortex she has in operation (and there is obviously something working there!), then it's making her hearing and vestibular senses more sensitive. The goal then is to increase her use of vision and the input she receives through her eyes so that her other senses can normalize (or at least calm down some). Can we do this by blocking her hearing and stimulating her vision for certain amounts of time? Will this in fact increase the use of her vision? And will use of her vision in fact calm down her vestibular sensitivity?
I asked the eye doctor this question and he told me he feared that blocking her hearing might create other sensory problems instead of helping her vision. He recommended working on improving that vision through multi-sensory stimulation (as opposed to working on one sensory element in isolation), and we of course are working on patching Sadie's eyes. The patching is done to help improve her ability to track her eyes together. Right now, her left eye drifts off some, so by patching her right eye, it causes her left to work extra hard to focus and track. But we want to make sure she's not losing out on development, so we patch the right eye for 2 days and the left for 1. And it is improving her vision as well as her ability to track with her eyes together.