Figure 4. Generation and characterization of naturalistic vibrissal stimuli.

a, Movements of an ex vivo B2 vibrissa during contact with a sandpaper-covered rotating drum were recorded to obtain naturalistic stimulation patterns (3 examples shown here, see text for details). b, Power spectral densities (dB units) computed for the three naturalistic stimuli shown in panel a, revealing a peak at ∼200 Hz. c, Histograms of the peak micro-motion velocities for all deflections in the three example waveforms. The range is comparable to velocities measured from the vibrissae of freely behaving rats³⁸. d, Distribution of deflections within cycles of optogenetically entrained gamma. For each stimulus, deflections with a peak velocity over 100°/s were aligned according to their latency from pulses of 40 Hz light. These high-velocity micro-motion events were evenly distributed throughout the gamma cycle, preventing any preferential phase alignment. e, Velocity envelope of the 3 naturalistic stimuli shown in panel a. f, Relationship between the integrated velocity envelope for the first 100 ms of each naturalistic stimulus and the mean detectability of that stimulus across N = 4 mice (1981 total trials), detection rates for the 3 traces shown in panel a are indicated.