Aspiring Svengalis rejoice! For BrainGate has reached a significant landmark in computational thought-control -- the 4 x 4-mm implantable chip has given a woman with tetraplegia the ability to point and click with her brain for 1,000 days. An article recently published in the Journal of Neural Engineering said the woman, known simply as S3, performed two easy tasks every 24 hours, using her mind to manipulate a cursor with 90 percent accuracy. Each day she was monitored, S3 would post up in front of a computer and continuously command