Fig. 3: vS1 coding of duration.

a Example vS1 recordings. Upper: spike waveforms and spike time autocorrelogram. Middle: raster plots of randomly selected 334-ms light-off and light-on trials. Lower: corresponding firing rates in non-overlapping 20-ms bins, light-on (blue) and light-off (black) trials. Single-and multi-units (right, left examples, respectively) pooled for analysis. b Normalized response of neurons (n = 250) on trials with stimulus 1 and 2 of 334- and 694-ms duration, respectively; intensity 64 mm/s. Above the response plots, example vibrations (plate speed across time) are illustrated as black lines. c Average response (as PSTH; see Methods) with light-off (left) and light-on (right). Light onset/offset matched vibrissal onset/offset. d Each dot shows population mean firing rate colored by vibration intensity in EYFP-ChR2(H134R)-expressing intensity rats (n = 3). In the bootstrap resampling algorithm¹³, the population (n = 138 neurons) is resampled to include 90% coding and 10% non-coding neurons (see Methods) such that the photoexcitation-evoked firing rate increase resembles the psychometric effect. Dashed diagonals in (d, f) denote equal firing for light-on and light-off. e Each dot shows population mean firing rate (bootstrap resampling) colored by vibration duration. Distributions shown as marginals. For 334-ms duration, points are projected parallel to the diagonal to give the green histogram. f Same as (e), but for spike count summated across the entire stimulus presentation. g Points (obtained by resampling) depict elapsed time to reach a given spike count (see color scale), light-off vs light-on. h Left: light-off (black) and light-on (light blue) population PSTH in response to 694-ms vibrations; 1 ms bins with 15 ms smoothing. Detected response onset and offset given by left and right vertical lines. Right: Points (obtained by resampling) colored by actual vibration duration (f), show stimulus duration estimated by elapsed onset-to-offset time of evoked activity with light-off and light-on. Diagonal denotes equal duration for light-on and light-off. Inset: Normalized difference in estimated duration (light-on – light-off) across all durations fails to uncover any significant photoexcitation-evoked shift (p = 0.147). i. Left: same as (h), for integration hypothesis. Right: Points (obtained by resampling), colored by vibration duration, show spike count summated from onset to offset. Inset: Normalized difference in onset-to-offset spike counts (light-on – light-off) across all durations uncovers a significant photoexcitation-evoked shift (p = 0.006). h, i use the color code of (c). Statistics for (h, i) derive from 1000x resamples from 138 neurons. Box plots (Matlab function boxchart): the central line is the sample median, the edges of the box are the 25th and 75th percentiles, whiskers extend to the most extreme data points not counting outliers, and the outliers are plotted as circles. One-sided permutation test (1000×) applied for statistical significance. Source data are provided as a Source Data file.