Star Trek: 10 Things We NOW Know About The Holodeck

4. Some Of The Coolest Holographic Tech...Came From The Mayans

If you'll allow us a little indulgence, Voyager's sickbay effectively serves as a dedicated holodeck, without which the Doctor couldn't (initially) have existed. For The Phage, this technology became a focal point for the introduction of Star Trek's latest villains, the Vidiians. 

When creating this new race, Jeri Taylor took inspiration from Mayan history, particularly that of human sacrifice and cannibalism, but focussing on why they committed such acts. According to Cinefantastique, this, combined with Brannon Braga's idea of a new villain that resembled Frankenstein's Monster, gave the Vidiians their motive.

Their first victim was going to be Tom Paris, who would lose his heart to them - and that in the least romantic way possible. Lacking this vital organ, the Doctor would create a new holographic replacement. Though the logistics of this, such as confining another member of the main cast to sickbay, proved too much for the producers to consider, it gave birth to Neelix's lost lung, and to the idea that holo-technology was so advanced by the 2370s that it could create replacement organs, fully fuctional, and ready to deploy. 

While this would require a holographic emitter on hand at all times, it was a massive leap forward in the tech. However, as presented in the episode, Neelix's lung is supported by a holo-chamber and he is paralysed, as it can't handle movement. You win some...