The brains of the Cogitors were put in jars full of electrafluid. The liquid provided all the nutrients and life-extension prerequisites to keep the brain alive. The liquid also had such a quality, that made visible the mental activities (as shimmering buzz) inside it.
Electrafluid also had some interesting properties. If an individual (usually a Secondary) dipped a part of their body into a brain-occupied electrafluid, the liquid would connect the brain with that person's neural system, allowing them to feel the brain's thoughts and speak on its behalf. The electrafliud therefore was a neural 'bus'.
Electrafluid was contained also in the Preservation canisters of the cymeks.