I find this as a large part of Asperger's. There is this need for some sort of over stimulus in sensory, or maybe there is the need to not have it at all. What I mean in this is that maybe a person might need to be moving all the time or touching and feeling, but then another person with Asperger's might be someone who hates touching or spinning or jumping.
With MJ, he always seemed to be spinning. Jumping, dancing and spinning, he had to be moving all the time. He didn't like to sit still. Along with his spinning and toe walking, it didn't surprise me when one day he came to me and asked if he could take ballet classes. He already didn't like any sports, and so I thought this would be something fun as an extracurricular activity that he could do.
Not just the spinning and moving, but another thing we always noticed with MJ was his lack of personal space. He was always overly groping people I thought. Now, I don't mean this in an ugly way, but he just would be a little too grabby or huggy snuggly up with people. Surprised? Most people who think Asperger's think anti social and don't like to be touched, but really it still breaks down to the not understanding social rules or norms so to say. MJ would sit too close to people, hang on them, snuggle up to them, and always talk to them right up to their face.
This has caused a lot of problems when it came to school or church. He didn't understand or maybe he didn't realize how close he was getting to people. Once at school another boy punched him in the stomach for getting in his space. It's nice for a boy to be loving and snuggly, but it's not great in any given situation. You probably shouldn't be snuggling on up with your new church teacher or whoever strange person you come across.
Now, as far as underload, or the need to not touch or feel---this comes across all sorts of ways. The whole walking on toes things was pinpointed to the sensory need to not have his heels touch the ground. Or what about the way clothes scratch and poke? As an NT, I don't seem to have that much problem wearing something a little scratchy or whatever, but give a stiff shirt to an Aspie and they will just about freak out. I find this more with my husband who thinks he is going to die sitting through a church meeting in a button up shirt.
Or, what about the need to not have people touch you? I am very lucky that my husband is not an Aspie that hates to touch or be touched as far as in a relationship, but at the same time he says that he can't stand to be sitting in a group in a small setting where his knee might possibly touch someone elses. It about kills him trying to focus on not moving his legs or feet in the chance he might touch another person.
We work with MJ as far as his sensory issues by letting him be in dance and spinning away, and then trying to teach him about personal space and when it's OK to hug someone or not. Everyday is a teaching day as far as "what should you do in this situation".