According to a report published this week in Nature, the scientists, including teams from the University of Vienna and MIT, have developed a technique to show neural activity (including the entire brain) of simple live animals in a video format.
The video link below shows the neural activity throughout the entire body of a specimen of Caenorhabditis elegans, a tiny nematode (we'll call him Charlie).
The good news for Charlie is that he doesn't have to be sliced open to see what he's thinking.
Because he's relatively transparent, it's fairly simple to see what's going on, especially when his neurons are specially prepared with a fluorescent chemical that is triggered when the neuron activates.
With 302 neurons, the nematode is a very simple organism, but the technique may be applied to other creatures in the future. Mice and rats are in their plans, although humans are likely to be a challenge, given that our skulls aren't usually transparent.