Unraveling ChR2-driven stochastic Ca2+ dynamics in astrocytes: A call for new interventional paradigms
Fig 3
Response of a ChETA-expressing astrocyte to various light stimulation paradigms.
Simulations were conducted to evaluate astrocytic Ca2+ response to different paradigms ranging from T = 1–5 s and δ = 0–100% of T (trials = 5). A) Heat maps of Ca2+ basal level (top panel) and spiking rate (bottom panel) for the T-δ combinations assessed. Each column depicts basal level and spiking rate heat maps up to a certain point, i.e. 45, 90, and 270 minutes, to determine the cell response as light stimulation progresses from short-term to long-term. Scale bars for heat maps of basal level and spiking rate were capped to 3 μM and 0.6 spikes/min, respectively. The △ and ◊ symbols correspond to T-δ combinations that result in the traces of panel B. B) Representative [Ca2+]c traces corresponding to T-δ combinations highlighted in A [Top trace (△): T = 2 s, δ = 1% (0.02 s); Bottom trace (◊): T = 4 s, δ = 45% (1.8 s)]. The inset of each trace highlights a 15-minute section to show the detected Ca2+ spikes. For spike detection, a threshold of 0.2 μM above the basal level was utilized. Each vertical solid grey line denotes the time points corresponding to heatmaps of panel A. C) Average (μISI) vs. standard deviation of ISI (σISI) where each point corresponds to a single simulated 270-min [Ca2+]c trace. Solid line shows the linear fit between μISI and σISI values. Throughout the manuscript, △, ○, and ◊ represent paradigms resulting in low, medium, and high Ca2+ spiking during short-term (45 min) stimulation of astrocytes, respectively.
