Fig. 5
Rapid divergence of evoked, reliable activity. a1 Population raster plot and population peristimulus time histogram (PSTH) for all 31,346 neurons in the microcircuit, during evoked activity with a thalamic (VPM) stimulus. Neurons are ordered according to cortical depth, with deep layers at the bottom and upper layers at the top, and each row representing the spikes of one neuron. For visibility, raster lines extend over dozens of rows for each neuron. a2 Mean somatic membrane potential correlation rV between independent simulations of the same VPM stimulus (mean ± 95% confidence interval). a3 Schematic of the VPM stimulus. Top: Raster plot spike times for the first 250 ms of the thalamic stimulus. Bottom: 310 VPM fiber centers are assigned 30 colors, and those with identical colors are provided with duplicate spike trains. The synapse density profile across layers for each fiber is shown to the right. b For t < 100, the top and bottom raster plots show the same simulation, whereas for t > 100, the raster plots depict two resumed simulations starting from the same saved state at t0 = 100, using different random number seeds. c1 Resuming from identical initial conditions at different times: during (top), at onset (middle), or before the stimulus (bottom). Mean rV between independent simulations (blue, as in a2), and mean rV between simulations starting from the same base state (red; mean ± 95% confidence interval). c2 The similarity, sr, defined as the difference between the rV of diverging and independent trials, normalized to lie between 1 (identical) and 0 (fully diverged) (mean ± 95% confidence interval). Means are based on 20 base states, no stimulus (spontaneous activity) on 40 as before
