dr. leigh hochberg: scott, cathy now has neural control over that cursor. >> pelley: dr. achusetts general hospital is leading the clinical trial. we watched together as cathy showed us what she can do. we're seeing cathy moving this cursor with nothing but her mind? >> hochberg: that's right. she's thinking about the movement of her hand, and she's moving the cursor much as if she had her hand on a mouse. >> pelley: so if a patient who's paralyzed thinks, "move my left arm," the brain fires those neurons? >> donoghue: yes. >> pelley: even though the arm does not move? >> donoghue: yes. it's very surprising. it fires, even though you're not moving. >> hochberg: the cursor is still a bit wavy. >> pelley: moving the cursor with her mind is not as fluid or direct as using a mouse. while we were there, the cursor meandered a bit, sometimes overshot, but cathy always hit her target in the end. >> hochberg: do you want to play some music? all right. she'll click on it. imagine squeezing her hand, which is... or doing something else for the click. >> pelley: and she just clicked