Fig. 10.
Conditional entropy hm for two representative afferent spike trains (solid line) as a function of order m. The mean hm for 49 surrogate sequences which matched the data exactly up to order (m − 1) are also shown (□, dash line). Afferent hm, which were significantly different from surrogate data are shown as *. Differences between afferent and surrogate data which were not significant are shown as ○. A, Afferent spike train that was described by a third-order Markov process. B, Spike train for which surrogate and afferent data sets had significantly different hm for all orders tested. Testing terminated because of insufficient data. The order of the process was at least 5, i.e., the number represents only a lower-bound. See Table 1 for a summary of testing.