MPTP treatments and clinical score of monkeys. The rhesus monkeys were treated with MPTP at the time points indicated by the color-coded asterisks. Doses were given on two consecutive days at the amounts (in mg/kg) indicated under the asterisks. The Kurlan rating score (rating the animal's posture, gait, tremor, general mobility, hand movements, climbing, holding food, eating, balance, gross motor skills, and defense reaction) is given for each monkey over time. Untreated control animals and animals before MPTP treatment had values of 0 (normal), higher values indicate increased deficiency. Daggers indicate time of sacrifice of each animal.