The clues vary, and many of the "typical" signs are misleading or even contradictory. One patient acts impetuously while another seems to have lost his spontaneity. Still another shows aggressive, animalistic behavior--or becomes apathetic, perhaps curling up in the fetal position or sucking, rooting, or grasping as an infant does. Some patients can memorize and recite a long list of numbers, remember events of the day before, and recall many of their childhood experiences--yet they "forget to remember" why they went to the store. When this happens, it's likely that the frontal lobe isn't performing its goal-orienting function as it should. If a patient takes small steps, has trouble initiating a step, or can't seem to find and keep his center of gravity--or if he involuntarily resists or aids an attempt to move his neck, arms, or legs--he doesn't necessarily have Parkinson's disease; he may have a frontal lobe lesion instead. Usually--but not always--the easiest way to find out is to check for a resting tremor.