Figure 7.

Branching parameter assessed throughout seizure evolution. The branching parameter σ was estimated using the avalanche approach across 1000 frames of generalized seizure periods in 10 frame bins. Two datasets were excluded based on the absence of clear transitions from nongeneralized to generalized activity, or insufficient frames following the transition initiation. σ remains close to 1 in the leadup to the generalized seizure and drastically increases as dynamics become highly synchronous, for most datasets (2, 3, 4, 5, 7, 8). Interestingly, following initial increases, σ quickly returns to ∼1 while high synchrony is ongoing. Note that for some datasets (1, 6) σ remains close to 1 until after the onset of highly synchronous activity. Oscillatory dynamics following the peak of synchronous activity are characterized by moderate increases in σ above 1 (3, 7).