Figure 7.

Place cell ensemble activity in the cylinder and chamber. A, The amount of ensemble activity (magnitude of the ensemble firing rate vector) was similar in the two conditions across a broad range of timescales. B, Decoding the rat's position in the cylinder was much better than in the chamber for modestly sized (5–25 cells) place cell ensembles. Decoding position from simulated spike trains was similar (slightly better) than using the real spike trains. C, Decoding with a simulated ensemble of 322 spike trains was similar in the cylinder and chamber (cylinder slightly better). Decoding was optimal at 250 ms resolution. D, Decoding at 250 ms resolution improved with the size of the simulated ensemble. Decoding in the chamber was worse than the cylinder until ensembles of ∼200 cells or greater were used. Chance in C and D was determined by randomly selecting an estimate of the rat's location for each time step that the population vector was not null.