1.   At first, the dopamine cells would fire when the animals got the juice or saw the light, since the reward was not expected.

2.   A hallmark of the disease is that dopamine cells in the substantia nigra become clogged with tiny, gunky clumps of abnormal protein called Lewy bodies.

3.   But when they were no longer surprised by the reward, their dopamine cells no longer fired, Schultz said.

4.   Dopamine cells have no intelligence, Sejnowski said.

5.   Electrodes were placed in monkey dopamine cells and the animals were given squirts of apple juice paired with a flashing yellow light.

6.   If the factor was added before the toxin, dopamine cells were protected.

7.   Scientists are still debating whether the dopamine cells ever fully return to normal.

8.   The controversial fetal tissue transplants, which can help produce new dopamine cells, is recommended for younger patients with the disease.