Sentence:  The fact that similar cortical abnormalities can be experimentally induced in monkeys has allowed Michael Merzenich and his colleagues in San Francisco to explore an animal model of focal dystonia, and to demonstrate the abnormal <WSD>feedbacks</WSD> in the sensory loop and the motor misfirings that, once started, grow relentlessly worse. 
Meaning of the word marked with <WSD> tags:  The signal that is looped back to control a system within itself.