Higher cognitive functions including things such as learning and behavior depend upon having normal sensory integration.
As a psychologist, I am sad to say that when I was in graduate school, (1982 - 1987) that this disorder wasn't talked about much. At this time I am often involved with families who have a child with Sensory Integration Disorder.
Imagine, if you will, that for each of your 5 senses, there is a wire of a different color that leads the information form that particular sense, into your brain. For example, for the information that comes in from your eyes, or your visual senses, you might imagine a red wire; and blue one for hearing (auditory), etc.
Now, assuming that your brain was able to notice what color of "wire" the information was coming from, and knew that the red "wire" was information from your eyes, and blue was from your ears, it would be a fairly straightforward process for keeping things figured out. Someone with SID, however, doesn't experience it quite like this.
When someone is dealing with SID, their brain is getting mixed signals. At times, the red "wire "might be visual information; at other times, it might be the blue "wire" that is shuttling the visual data. Then, there may be times when the red "wire" is carrying both visual and auditory information. Can you see how this might be very confusing for the brain to interpret?
This sounds like a rather complex challenge, does it not? One could argue that it is, I suppose, but I've never been one for building a "case" for difficulty. Instead, I prefer to gather evidence for possibility.
In short, when neurofeedback is helpful for those with SID, it's as though neurofeedback is able to teach the brain to start recognizing the "wires" accurately and stop acting "color blind" when it comes to incoming sensory information. And, why shouldn't everyone's brain learn to clearly interpret sensory information?