DIM BULB: Music and politics are a powerful but tricky combination. The use of the Heart song, “Barracuda,” to introduce Republican vice-presidential candidate Sarah Palin has raised protests from band members Ann and Nancy Wilson, who said they did not and would not have given permission for the song to be used. The protest follows legal action from Jackson Browne last month over the use of his song, “Running on Empty,” in a campaign commercial.