Have you thought about stimulating baby with smells? A newborn's sense of smell is well developed. She is capable of distinguishing smells he likes and those he doesn't. But smell is not merely a pleasant sensation, it has also been found to be important for motor growth promoting involuntary and skeletal movements. In other words - your baby sniffs and automatically has a reaction!
Offer your baby some pleasant smells: mom's perfume and dad's cologne. Put on cotton ball and wave under baby's nose 3 times. Watch for baby's reaction (if you do not wear perfume or cologne try to identify something similar that identifies each of you via smell - perhaps mom's breastmilk or dad's deodorant - as long as it is something pleasant)