Fig. 2: Temporal spiking patterns in somatosensory cortex carry texture information.

A Classification performance (percentage of textures correctly classified from the full texture set, comprising 59 unique textures) is best at high temporal resolutions (1–5 ms). The temporal resolution denotes the standard deviation of the Gaussian filter used to smooth the neuronal response. Performance derived from example neurons is shown in black and dark gray, mean performance across all cortical neurons is shown in blue, mean performance from rate-matched Poisson simulated neurons is shown in light gray. Simulated Poisson responses, which do not carry texture information in their timing, yield chance classification performance (1/59 textures ~ 2%). Shaded area denotes the standard error of the mean. B Single-cell classification performance for all 141 neurons for rate (red), timing (blue), and their optimal combination (purple). Dark points denote the example neurons shown in panel A. Violin plots show all values. Boxplots indicate median (center), interquartile range (boxes), and maximum and minimum (whiskers). C Mean classification performance with neuronal populations of different sizes; shaded area denotes standard deviation across 1000 iterations at each sample size. Timing-based classification (blue) yields better performance than does its rate-based counterpart (rate) for very small groups of cells, but timing-based performance levels off at a much lower level than does rate-based performance. Rate is nearly perfect with even a small population of 50–100 cells, but a combination of rate and timing (purple) is better for neuronal populations of any size and reaches 90% performance with only 13 cells (as compared to rate, which requires 29 cells).