To simplify it a bit more (but not to lose correctness) it seems like this molecule is a maintenance signal, meaning the path is in use. If it's not present th

To simplify it a bit more (but not to lose correctness) it seems like this molecule is a maintenance signal, meaning the path is in use. If it's not present the channel gets closed. The whole purpose is to make it possible for a synapse to wither, because to reorganize something needs to be tore down.