Enrichment of the RUN sequence during spike avalanches.

The RUN sequence occurs at different rates in different Markov chain models (avalanche independent, true, and RUN-optimized; columns 2–4 respectively). In the fitted model the RUN sequence occurs at a rate between 1.3- and 2.2-fold higher than under the temporally unstructured avalanche independent model demonstrating that there is a statistical enrichment for the RUN sequence in the burst sequence (column 5). The true enrichment is only a small fraction of the amount possible given the burst rates. Under the RUN-optimized model, the RUN sequence occurs at rates between 60- and 2x108-fold over the avalanche independent model (column 6). This demonstrates that the fitted model is not producing the RUN sequence close to the theoretical maximum rate.