For the first time, scientists have image-mapped an entire brain at the cellular level.

In a study published in Nature Methods, researchers from HHMI's Janelia Farm Research Campus have mapped the brain of a fish larva, at such a detailed level that individual neuron activity can be seen.

The brain mapping is fast, too. Using high-speed light sheet microscopy, the researchers were able to map the entire fish brain in 1.3 seconds. This means that, for the first time, scientists are able to watch a vertebrate brain function in (approximately) real time. We can now watch a brain think.

The new development comes at an exciting time for neurology. Earlier this year, President Obama announced plans for the Brain Activity Map Project, which will seek to map the activity of every neuron in the human brain in 10 years.

Granted, a zebrafish brain is much smaller and simpler than a human brain, but this activity is a great starting point for the Brain Activity Map Project. The project has not yet presented its main goals and timetable, but it could be a scientific achievement similar to President Kennedy's push to land a man on the moon by the end of the 1960s.

In addition to mapping the brain, the researchers also made discoveries about the brain they studied. They found, as Nature reports, "correlated activity patterns measured at the cellular level that spanned large areas of the brain — pointing to the existence of broadly distributed functional circuits." Next, the team will study how these circuits affect and translate to behavior.

You can watch a video of the brain map here.