Figure 6. Neural correlates of cue conflict that are idiosyncratic but consistent within individual rats.

(A) Grid degradation. Rate maps and autocorrelograms of 4 grid cells recorded from four different tetrodes in rat 387 in both STD and ROT70 on four different days (including the first and last days in which grid cells were obtained in ROT70). The equilateral triangular structure, but not the multi-field nature, of the grid cells was dramatically reduced or entirely lost in ROT70. Rate maps for all sessions in which these cells were recorded and additional examples are given in figure supplement 1. (B) Grid realignment and dissociation from boundary cells. Rate maps for two units and all sessions of one experiment day, from rat 292. After varying amounts of realignment in the ROT20 and ROT70 conditions (i), the grid reverted back to its standard alignment relative to the platform boundaries in the SHIFT condition and shifted along with the platform (with a minor CCW rotation, as described in Figure 4B and G). However, in STD2, the grid did not maintain this standard alignment. Instead, the grid reverted to the same alignment relative to the platform boundaries that it had adopted in the ROT70 session. Pearson correlations between relevant maps quantify the poor overlap between STD and STD2 and the strong overlap between ROT70 and STD2 (after the ROT70 was rotated 20° CW). A simultaneously recorded boundary cell (ii) always fired along the upper platform boundary, dissociating from the realignment of the grid in ROT20, ROT70, and STD2 (re-illustrated as first example in Figure 7A). (Additional examples are given in Figure 6—figure supplement 2 and Figure 7A.) (C) Pearson correlations between rate maps from STD vs. STD2 (n = 4), STD vs. SHIFT (n = 6), and STD vs. the manipulation found to induce the new alignment in STD2 (n = 4), in a given day, for all grid cells and days in rat 292. Values referring to the same unit and day are linked. (D) Grid orientations in the standard sessions sampled over the course of 13 experiment days. Dot size is proportional to grid scale. Grid orientations in STD sessions (blue) are consistent across days in spite of the change of orientation experienced in STD2 sessions (red).

DOI: http://dx.doi.org/10.7554/eLife.21354.018

Figure 6—figure supplement 1. Selective loss of hexagonal grid structure in rat 387.

(A) Examples of grid cells that selectively lost or weakened the characteristic hexagonal structure in ROT70, including rate maps and autocorrelograms for all sessions recorded. (B) Examples of grid cells that passed the gridness test in the ROT70 manipulation but were subject to strong distortion. This distortion manifested itself in the autocorrelogram as an elliptical compression of the hexagonal pattern. (C) Example of boundary cell recorded in this animal. This cell functioned normally and tracked the same geometric boundary in all sessions, including ROT70. While a simultaneous recording of a grid cell lasting into this session was not available, in this rat grids dissociated from the platform boundaries in ROT70 (B, and Figure 3A), when they were not utterly disrupted (A, and Figure 6A). It is thus likely that a dissociation between grid and boundary receptive fields occurred in this animal, similar to rats 292 and 377 in Figure 7A,B.

DOI: http://dx.doi.org/10.7554/eLife.21354.019

Figure 6—figure supplement 2. Bistable anchoring of grids across reference frames and experimental sessions in rat 292.

All sessions are illustrated for grid cells recorded on the days when STD2 was run, in addition to the two cells in Figure 6B. Illustration and notations follow Figure 6B. In all examples, the alignment of the grid relative to the platform boundaries in STD2 differed from the alignment in STD but was the same as in a previous manipulation. The manipulation inducing the realignment affecting STD2 always preceded the SHIFT condition, regardless of the type of manipulation and the manipulation sequence. The STD2 session always inherited this orientation, even as markedly different orientations were experienced over the 1–2 intervening sessions. On Days 12, and 13, boundary cells were recorded simultaneously with the grid cells, similar to Figure 6B.

DOI: http://dx.doi.org/10.7554/eLife.21354.020