Scientists Watch a Fish Think; It's Not 'Just Keep Swimming' (Video)

Fish may not be thinking "just keep swimming." A new study by Japanese scientists is the first to produce a real-time recording of the exact brain processes at work in an animal carrying out its natural behavior. In this case, it shows the thought process of a fish as it tracks its prey.

The finding, published in the journal Current Biology, shows that fish (at least, zebrafish) tend to think a lot about food: how to obtain it and what to consume. The researchers used a very sensitive fluorescent probe that detects the activity of neurons. They then inserted the probe right into the neurons of the zebrafish using a genetic method. It allowed them to detect neuronal activity at a single-cell resolution.

Zebrafish are often used to study genetics and development in vertebrates. Their larvae in particular are ideal for neuroimaging because they possess translucent heads. This allows scientists to directly see into the fish's brains.

During the experiment, researchers applied several different stimuli to the zebrafish. First, they introduced a dot blinking on and off or moving back and forth on a screen. Then they introduced live prey for an immobilized zebrafish and watched the neural signals. Finally, they placed prey in front of a free swimming zebrafish.

The researchers found that signals flashed through the fish's brain in all of the experiments, tracking the movement of the dot and the prey. When the fish was able to pursue the prey, the researchers mapped the brain activity as the zebrafish zeroed in on the food and swam toward it.

The results of these experiments will improve researchers' understanding of brain circuits involved in predatory behavior. It could also be used to image other brain areas, as well.

Want to see how a fish's brain really works? Check out the video below, courtesy of Current Biology.