Place fields
Be the rat. Move through the room and watch eighteen simulated units fire, each in its own patch.
unit 07 0.0 Hz mean 0.00 bits/spike driven by simulated rat
What you're looking at
The square is a room seen from above. The grey line is the path, yours or the simulated rat's. Each row on the right is one unit, and each tick is a spike. The selected unit's spikes are also drawn in red in the room, at the place where each one happened. Click a row to select a different unit.
Every unit has one field: a patch of the room where it fires at up to twenty spikes a second, and almost never outside it. Turn on true field to see where the selected unit's patch is, or leave it off and find it by walking.
The score
Bits per spike is spatial information, the standard score for a place cell. The room is cut into a 12 × 12 grid, and each bin gets a firing rate: spikes in the bin divided by time spent there. The rate map toggle shows that grid. The score is high when a few bins hold most of the firing, so that one spike tells you a lot about where the animal is. It keeps changing as you explore, and it's biased upward until you've covered the room.
Why it's here
These units are place cells by construction. Real recordings, and model activations, have to earn the name, and passing this test turns out to be easy: a unit that responds to one view of the room passes too. Everything on this page is simulated.