To put simply sensory integration is the ability to take in, sort out , and connect information from the world around us in an organized manner. Sensory integration allows to put this all together to have and experience of eating an orange. Sensory integration nourishes the brain by helping the brain properly digest the sensory information it receives. Every moment countless bits of sensory information bombard our nervous system. It is estimated that 2 million bits per sec enter the central nervous system.
Sensations are the food of the brain.
Without adequate sensory information the brain gradually becomes disorganized. In sensory deprivation tanks at first the person relaxes with the reduction in sensory stimulation, however after prolonged periods gradually the person become disorganized and start to hallucinate sensory information, much like a person in the desert hallucinates water. The brain needs sensation and without it, it will create it's own. With too much unmodulated sensory information a person is also overwhelmed and they can either become over stimulated or so overwhelmed they shut down. So the brain needs sensory information as food yet sensory integration can be thought of as how we digest that food.