Hi Amanda - volume isn't too high today all things considered. What often happens when events like this occurs is that it takes a couple days for the word to work thru the market (keep in mind NVIV is still OTCBB) as well as early investors may 'cash out' at this stage with a 5-fold return on their initial investment, etc.
Once the investors who want to 'cash out' are done and the news filters all the way thru to institutional money the PPS begins to pick up.
No guarantees obviously, but wouldn't be surprised if we don't see strong pick-up action until tomorrow and even into next week.
All of the foolish day traders who jumped in at the open took their profits or panicked out of it when it got sold off, the smart money who knows the real value of the future are loading up on the pull back, they know it's worth we'll over $3.00 in the future.
Even smarter money knows it will blow past the puny $3 level as well. Some may be holding off until a formal announcement on the IDE. Once that is announced, there will be an even bigger leg-up because that is the green light for the trials.