Figure 5

Dependency on sensory thresholds. (A) Left: each data point represents the median tangential speed (y-axis) across all trials of the first session and the middle finger JND (x-axis) of one participant (18–29 trials per participant). Right: probability distributions of r and p values across a bootstrap sample (N = 1000) of possible JND values, assuming known unreliability of JND measurements (see “Materials and methods”). Experimental r and p values are marked by the dashed blue lines. Black vertical dashed line represents p = 0.05. (B,C) TouchSim simulations (see “Materials and methods”). (B) The mean number of spikes per neuron (y-axis) plotted against tangential speed (x-axis). Color code represents the distance between units in the grid (2–4 mm). The range of speed used by our participants is marked by the dashed gray lines. (C) Histogram of SD values between firing rates of neighboring neurons, for either the window containing speed values used by our participants (dark gray) or all other equal-size windows (light gray). (D) Each two connected data points represent one participant’s mean adaptation time (Ta) using Linear (light blue) or Oscillating (blue) motion (11 Linear and 11 Oscillating trials per participant). Median values for each motion type are represented by a larger shape (median Ta  Oscillating = 29.07, median Ta Linear = 22.9 s). (E) Curvature approximation. The curvature index (see “Materials and methods”) during one example trial is color coded along the trajectory. (F) Each data point represents the median curvature (across all trials of the first session) and the mean Linear Ta of one participant (4–24 CF trials per participants). (G) Number of spikes (y-axis) over time (x-axis) for a grid of RA units for either Oscillating (blue) or Linear (light blue) motion. The time of deviation from the contour, in Oscillating motion, is marked in black. (H) Black: correlation coefficient between JND and tangential speed (y-axis) per session (x-axis). Light blue: absolute value of the negative correlation coefficient between the curvature and adaptation time (y-axis) per session (x-axis). N = 10 participants, for all panels.