Supplementary Figure 8: The impact of HCN1 loss on spatially modulated cells is restricted to grid cells.

P-values are provided in Table 1. (a) Examples of border cells. Rate maps (top) are coded from maximum firing rates (red) to minimum firing rates (blue). Peak firing rate (left) and border width (right) are indicated at the top of each plot. (b) The width of border cells was not significantly different between iWT (blue) and iCre-KO (red) mice. Inset: Schematic showing border cell width calculation. Left: rate map of a border cell with black dots indicating the center of mass of each detected firing field. Right: fields detected from the rate map are shown in black. The width of each field was first calculated by averaging the distance at each point along the field’s inner edge from the wall associated with that field (the wall over which the field spanned the greatest length). A border cell’s width was then defined as the average width of all of its fields, depicted in this schematic as red lines. (c) The firing rates of iWT and iCre-KO border cells similarly decrease as distance from the nearest arena wall increases. For each border cell (n = 86 iWT cells, n = 71 iCre-KO cells), the average firing rate was calculated at increasing distances from the nearest arena wall (for example, the average firing rate was calculated for all bins located 1 cm away from the nearest wall, then 3 cm away from the nearest wall, then 5 cm away from the nearest wall, and so on). For comparison across cells, firing rates were normalized by dividing the firing rate at each distance by the peak rate at any distance. As expected for border cells, firing rates decrease with distance from the nearest wall (repeated measures ANOVA; main effect of distance: F(17, 2635) = 279.16, p = 1.0e-13). However, there was no main effect of group (F(1,155) = 0.029, p = 0.87), nor was there an interaction between group and distance from the nearest arena wall (F(17,2635) = 0.31, p = 0.81). Plot shows the mean and SEM for all iWT (blue) or iCre-KO (red) cells. (d) Examples of spatially stable cells. Black dots indicate firing fields. Peak firing rate and percentage of the environment covered by a firing field are indicate at the top left and right, respectively. (e) The size of the average field is similar between spatially stable cells recorded in iWT and iCre-KO mice. (f) The percentage of the environment covered by a field is similar between spatially stable cells recorded in iWT and iCre-KO mice. (g) Examples of interneurons recorded in iWT and iCre-KO mice. Color coding of rate maps as in (a). Peak firing rate is indicated at top. Right: Spike time autocorrelation diagrams. (h) Box plot showing that the interspike-interval latency of theta-modulated interneurons (n = 13 iWT cells, 16 iCre-KO cells) does not differ between iWT and iCre-KO. Box shows first and third quartiles, and whiskers show the maximum and minimum values without outliers (plotted separately). A solid line indicates the median. (i) Box plot (depicted as in [h]) showing that bursting frequency of interneurons (n = 15 iWT cells, 22 iCre-KO cells) does not differ between iWT and iCre-KO.