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

Figure 6

Plastic dynamics between the glia network and synaptic terminals in a circling wave experiment with 4-hour recording time. Potassium sensitive electrode and local potential recorded at the inner plexiform layer. The horizontal bars in each square show 7 minutes of time in the record. Below each wave is the number of the turns that reached the electrode tip. In the first 31 turns, the local potential did not show the “typical” potential drop and the extracellular potassium activity wave change showed low amplitude and changed shape (or kinetics). Then, at turn 32, a small potential drop appeared and the peak of the potassium waves increased to typical values. The potential waves also increased in amplitude but remained one order of magnitude smaller than the “typical” values (above 10 mV). Note the fast kinetics of the potential and ion activity waves at 40–42. Note also the small oscillations of potassium activity in (a) and (c) before the long (order of minutes) potassium increase that interacted with two propagating neuropil waves. The long potassium activity transient begins with a linear growth and potential rise within the neuropil; then, a second linear growth interacts with the turning wave invading the area and the extracellular potential drops. This second linear growth also had an IOS that showed a standing pattern that lasted for 24 minutes and faded without leaving lesions behind. The value of potassium activity reached 37 mEq/L. This value was maintained for 24 minutes and the return to baseline control levels took another 20 minutes. As usual, one wave was elicited at the border of the standing pattern and this wave killed the previous circling wave on collision. One hour after the circling stopped, the retina was readily excitable by mechanical touches and 8 waves were elicited with shape and amplitudes similar to the ones in 40–43 turns. This experiment illustrates well the plastic dynamics between glia and synaptic terminals membranes interactions and the nonlinear system response to any particular macroscopic wave concomitant precluding linear causality among these concomitants (modified from [79]).

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