...I mean no offense, but is she really the heart and soul? She does just one voice while all the other actors do multiple voices. I found that comment to be a little strange...

When Matt Groening comes out, he presents the Icon Award (he received it at the Futurama panel) to himself! Lastly, Yeardley Smith comes out and is introduced as the 'heart and soul' of the show.

12:53 Smith took a helicopter to get here but couldn't even get passed the security of SDCC without her credentials. Even after saying she's Lisa Simpsons... 'no ma'am.'

http://www.cinemablend.com/television/Simpsons-Comic-Con-2012-Live-Blog-44632.html

http://www.brimg.net/images/qa-yeardly-smith-1.jpg