Fig. 7: Trajectories following hypoxic insults.
From: Mechanisms underlying pathological cortical bursts during metabolic depletion
a–c Recovery failure. a Rapid [O2]Buffer decrease from the healthy state to a hypoxic isoelectric state (1), followed by delayed rapid return (2). b Network firing rate for brief (1 s, top) and long (2 s, bottom) hypoxic insults. Dotted lines indicate start (1) and end (2) of hypoxia. c Maximum duration at low [O2]Buffer (labeled as maximum survivable duration) for which dynamics return to the AI state as a function of hypoxic insult depth Δ[O2]Buffer. d–f Recovery via high \({[{{{{{{{\rm{{K}}}}}}}}}^{+}]}_{{{{{{{{\rm{Buffer}}}}}}}}}\) d Rapid [O2]Buffer decrease from the healthy state to a severe hypoxic isoelectric state (1), followed by a high-[K+]Buffer AI state (2), then recovery (3). e Network firing rate for brief (20 s, top) and long (30 s, bottom) elevated [K+]Buffer (=19.5 mM) periods. Dotted lines indicate the start (1) and end (2) of hypoxia, and start (2) and end (3) of high [K+]Buffer, returning to the healthy state (3). f Minimum duration of high [K+]Buffer to return to the AI state (labeled as minimum survivable duration) as a function of increase in [K+]Buffer from its normal value 3.5 mM (Δ[K+]Buffer). g, h Recovery via BS at high \({[{{{{{{{{\rm{K}}}}}}}}}^{+}]}_{{{{{{{{\rm{Buffer}}}}}}}}}\). g Top: Rapid [O2]Buffer decrease from the healthy state to a severe hypoxic isoelectric state (1), followed by traversing the BS state (2), an intermediate [K+]Buffer state (3), and recovery (4). Bottom: Zoom of the BS regime where [O2]Buffer increases gradually over ~5 h (solid black arrow). h Network firing rate. Top: Entire trajectory. Red boxes denote zooms in panels below. Middle: Hypoxic insult (1) and start of the [O2]Buffer increase during BS (2). Bottom: Final recovery. Dotted lines denote the rapid transition from the end of BS to the high [K+]Buffer AI state (3) and rapid return to the healthy state (4). i–k Activity termination in panel (b) due to K+ over-correction. Simulations for hypoxia durations between 1 s (cf. panel (b), top row) and 2 s (cf. panel (b), bottom row) hypoxia; onset denoted by black line. Activity survival shown in green, cessation in red. i Mean K+ across neurons. j Mean Na+ across neurons. k Mean [O2]o across neurons. Shading in panels (a), (d), and (g) is as per Fig. 4.
