Fig. 2: Speed cells are distributed across the parahippocampal cortex.

a Schematic representation of linear velocity movement (b) Schematics partial ring attractor depicting theoretical updating of positional code from position at time _t (left) to position at a later time _t+1 (right) following linear movement (middle). The outer layer of conjunctive grid-by-HD cells is connected to a ‘hidden’ inner layer of conjunctive grid-by-HD-by-speed cells. The colour represents neural activation from maximum (red) to minimum (blue). c Proportions of speed cells in MEC (left, 16.7%, n = 66), PaS (middle, 19.8%, n = 86) and PrS (right, 20.1%, n = 125). These proportions are not significantly different. d Example speed cells (left) and general distribution of speed scores (right) in MEC (left panel), PaS (middle panel) and PrS (right panel). The example tuning curve on the left plot shows the mean firing rate (red) as a function of speed, between 2 cm/s and 50 cm/s. Scores are in the upper right corner. The histograms on the right compare the observed (coloured curve) and shuffle data (grey bars), dashed lines represent the 99-percentile threshold. e Snapshot comparison between z-scored firing rate of an example speed cell (red curve) and instantaneous linear speed (black curve). f Scatterplot showing the correlation between the speed score calculated in the first and second half of the recording session (speed cells in red, rho stability = 0.61). Credits to Silvia Girardi for schematics and drawings.