Polar plots of six individual vS1 neurons during isolated ramp and hold vibrissa deflection (blue) and paired vM1-vibrissa stimulation (red). In these experiments, the principal vibrissa was randomly deflected to eight different directions (0°,43°,90°, 135°, 180°, 225°,270°, 315°) with and without paired vM1 optogenetic activation. Vibrissae were deflected in the different directions by two pairs of galvanometers. Upper four panels are from 50–60 day old rats, and the lower two panels are from 90–100 day old rats. Upper left panel-putative layer 2–3, upper right panel putative layer 5, middle left panel-putative layer 4, middle right panel putative layer 5, lower left panel-putative layer 5, lower right panel putative layer 2–3. Note, sharpening of the angular tuning curve following paired vM1 optogenetic activation.