The Plastic Glial-Synaptic Dynamics within the Neuropil: A Self-Organizing System Composed of Polyelectrolytes in Phase Transition

Figure 4

Experiment with fast high concentration KCl solution asperged over the inner limiting membrane (200 mEq/L and 200 µL) with an Eppendorf pipette. The local potential and local IOS (the average brightness of a 50 µm square matrix overlaying the electrode tip) were simultaneously recorded. In the upper row, the time series, calculated from the potential time series, shows two separated peaks. The potential time series is in the middle row and the µIOS in the lower row. Note that, in this context, both the IOS and potential show two components: a potential rise at the inner plexiform layer coincides with transient hypertransparency. We interpret this component as the “passive” response of the endfeet bilayer responding to the sudden potassium increase. Note that electroneutrality is broken for three seconds. Ten seconds later, the typical potential drop of retinal waves coincides with the typical wave light scatter increase. We interpret this response as the “active” response of the glial network/synapses, corresponding to the cooperative conformational change in the polyelectrolyte gel. The µIOS time series recovery stops at a plateau level, as well as the potential time series, although the small negative potential only lasts 5 minutes. Note also that in the 10-second interval between the two components the system is at a supercritical state. Ten seconds separates the two components and eleven seconds the two peaks of the µIOS. The potential drop has the typical one-minute duration of retinal waves recorded at the inner plexiform layer.