Neurosymbiosis

We have about fifty trillion cells, yet only eighty billion brain cells, and a mere thousandth the number of cells for a fifth the volume. And only a tenth of those are actual interneurons, the rest being glia cells that support them. So we have just 8 billion interneurons, one ten thousandth the number of cells in our body; and yet this is enough to contain everything we perceive in an entire lifetime, which can always be recollected from the unconscious through hypnosis.
But our neurons are mostly wiring, and the wiring is so thin that they can criss-cross all over the place. Our neurons have a lot of space, so that there is almost no limit to the number of connections that can be made between them: on average, each neuron is connected to a 1000 others, but in the cerebellum, this can be up to 7000, despite the fact that half of our brain cells are contained in this tiny part of our brain. Since the cerebellum has just about a twentieth the volume of the cerebrum, the density of connections is probably almost a hundred times greater than that in the cerebrum.
In theory, our cerebrum should be able to do this and become at least 100x more interconnected, and the only reason it doesn't is because it doesn't need to. But this illustrates how there is really no limit to how much information our brain can contain. This will be relevant to remember once technological telepathy comes along, as it means that we could easily absorb the entire memory of hundreds of other people if needed.
8 billion interneurons would not be much if they could each only connect with just a few other neurons like binary computers: but the brain is more like a quantum computer, in the sense that with each new neuron, bandwidth increases exponentially as the number of possible connections undergoes a "combinatorial explosion". For all intents and purposes, the potential of our memory is practically limitless. Only the processing speed of our brain is limited, mostly because of overheating.
Maybe we'll just interface our cerebrospinal fluid with a coolant to allow us to send our brain into overdrive, though this wouldn't prevent oxidative stress that would slowly cause the brain to degenerate, so if anything, it could be used in emergencies such as combat. Telepathy in itself will add to the quality of our consciousness rather than its quantity.
Imagine, though, what it would be like to remember hundreds of lives as if they had all been your own, and knowing only which one was actually yours because of your body. Such memory transplants would have to exploit the vocabulary already existing in the brain, so that the two lives would be integrated seamlessly as if they had co-occurred, and thoughts would freely wander from one life to another just as it wanders from one period of our lives to another.
But each life would have its own personality, and the desires of each life would come together and conflict until they'd find a way to unify into a single desire, the desire for consciousness, for life — and once they do, they will intensify each other, up to a point that we'd desire everything and everyone.