LONDON - The doctors prepared to carry out the brain surgery, their medical tools laid out. Their patient, wide awake on the operating table, was given an instrument of her own: her clarinet, which she began to play. Denise Bacon, 65, blew into the mouthpiece as doctors stood behind her, piercing holes into her skull to implant electrodes that would deliver electrical pulses to the brain in a bid to improve her motor skills. The electrodes were connected to a pulse generator - a device likened to a pacemaker - which sent continuous pulses to modify the brain, helping her manage her symptoms of Parkinson's disease, for which there is no cure.