Dr. Seung, Jinseop S. Kim, Matthew J. Greene and M.I.T. colleagues analyzed the structure of the starburst amacrine cell and its connections, considering previous work on physiology and the workings of neurons. From that, they proposed a mechanism for how the cell responds to motion in only one direction. It involves two other cells, bipolar cells that are excited by light and send impulses to the starburst cell.

If their analysis is right, the impulses from the bipolar cells have to reach the starburst cell simultaneously in order to make the starburst cell send out its own signal. Although one bipolar cell fires first as an object moves across the mouse’s field of vision, and another fires second, the signal of the first is delayed along the way so that the signals from both bipolar cells arrive at the starburst amacrine cell at the same time. That simultaneous stimulation causes the starburst amacrine cell to send out its own signal, which carries the news that something is moving in a particular direction on to ganglion cells and then to the brain itself. This is a simplified analysis because in reality many pairs of bipolar cells are reporting to any given starburst amacrine cell.

The system is very similar to the motion detection circuit in the fruit fly that Dmitri B. Chklovskii and his colleagues at Janelia Farm reported on last summer. Dr. Chklovskii, who is about to move to the Simons Center for Data Analysis in New York, said of Dr. Seung’s paper, “It validates our results with the fly.” And it raises all sorts of questions about how evolution produced such similar systems in such different animals with such different brains and vision systems, he said.

Calling Dr. Seung’s hypothesis “very bold,” Dr. Chklovskii added: “There’s not much wiggle room there. It’s a very concise model, a very specific mechanism that can be tested with existing tools.” If Dr. Seung is wrong, he will be clearly wrong.

If he is right, then his findings and Dr. Chklovskii’s study are steps toward cracking the code of the brain — exactly how information is coded and travels through circuits of neurons to allow perceptions to be formed, actions to be taken and decisions to be made.

A Drive to Get Data

That is, after all, why Dr. Seung “paused” in his theorizing to be able to put ideas to the test, another bold action. And the adjective is characteristic of his personality as well as his research. He has been called a “rock-star neuroscientist” in the news media, and he takes easily to the stage. In addition to developing Eyewire, he dances and mugs shamelessly for the camera in videos to promote it.