Figure 6. DL represents a variety of navigational variables other than location.
(A) Examples of head direction cells in anterior DL, showing two cells with narrow tuning (top) and two cells with broader tuning (bottom). Each plot shows firing rate as a function of head direction in polar coordinates. Peak firing rate in calcium events per second is indicated for each cell.
(B) Fraction of cells identified as head direction cells in each of the recording sessions. Different symbols are used for different birds. Horizontal lines indicate medians. Head direction cells are found in all three regions, with higher abundance in the hippocampus (p<0.001 Wilcoxon rank-sum test).
(C) Examples of speed cells in anterior DL, showing three cells with positive speed tuning and one with negative speed tuning.
(D) Fraction of cells identified as speed cells, plotted as in (B). Speed cells were found in all three regions.
(E) Example 3 min trajectory of the titmouse overlaid on a 3D schematic of the recorded arena. Behavioral data points are recorded every 50 ms. Trajectory indicates periods of relative immobility separated by fast, ballistic “dashes”.
(F) Example recording of the bird’s speed, showing four dashes.
(G) Examples of cells in anterior DL with modulation by time relative to the dash. Zero indicates dash onset. Each trace is an average across all dashes recorded in the session.
(H) Fraction of cells identified as dash-modulated cells, plotted as in (B). Dash-modulated cells were found in all three regions, but were more abundant in anterior DL compared to the anterior hippocampus (p<0.05 Wilcoxon rank-sum test).
(I) Activity of all dash-modulated cells in anterior DL, sorted according to the time of the peak firing rate. Each cell’s activity is normalized from 2.5th (blue) to 97.5th (red) percentile of its firing rates in the plotted window. Firing of all cells is concentrated around 0.5-1 s relative to the dash, but forms a sequence spanning the entire event.