Neurons were selected by evolution for their speed of transmission of information, and hence a rapid response to a stimulus. Why should the particular speed(s) at which they can convey information be important in the scheme of things? After all, not all life forms have neurons. The plants do especially well, but even they are superseded by the bacteria when it comes to evolutionary longevity. What I'm getting to is, why has the particular speed of transmission (OK it varies somewhat, but the ballpark) been selected for and settled upon? What are the biochemical/physiological limitations? What does this say about information processing and limitations for intelligence? Shouldn't we be putting more research into biosilicon systems so we can speed the processes up? I mean with some urgency. Relatively little work is going on. Why? What are the hurdles? What ere the timescales (for getting results)? I've trawled the literature and its not very exciting.

what is your evidence that "neurons were selected by evolution for their speed of transmission of information", as opposed to being selected for diversity of function, adaptability, or some other measure? Silicon still cannot rival the complexity and adaptability of Nature's wetware creations, so it's likely there's more being selected than just speed of information transmission.

Indeed, if a person wants to speed their brain up, they should look to aiding the brain in its natural process rather than trying to add a artificial one.

The relatively slow signal transduction that is/was available to non-neuronal cell types and increasing evolutionary multicellular complexity, organismal size and thus distance for information transfer, sort of make it a bit obvious that a speed injection would have been needed. All of the diversification of neuronal types and configurations would have come later and are not relevant to my statement about an original selection for cells with speed.

See Philosophy/Brain Theory by Steven Michael Harris:

An evolution of cellular specialization was needed for the much larger colonies of cells. Larger organisms could not function effectively if all of the cells communicated in the same early way of chemically signaling cell by cell, membrane by membrane, across the entire breadth of the colony. A type of cell that could quickly send a message from one end of the colony to another was very helpful to survival. This cell that quickly sent the messages (of pleasure or pain) from one end of the organism to the other needed to have more sway in the decisions of the accumulated cells for the success of the organism. (Otherwise the messenger cell, or nerve cell, signaling activity in the distant parts of the colony would always be overruled by the signaling of the local cells at various parts of the colony seeking a pleasure or avoiding a pain.)

Somehow these early nerve cells were able to evolve a lightning-fast action potential that could signal instantly from any point in the colony to another, and this type of cell also developed a magnified sensation of emotion (pleasure or pain) in the signaling so that the nerve cells (able to communicate the voting from the far reaches of the colony) had the greatest influence on decisions in the system making survival much more likely for the greater organism as a whole. (Think of nerve cells as the executive or national organization, and the other kinds of cells as the local organizations.)

This was the beginning of mental processing and higher intelligence and all that matters from this point on is the size and the organization of this nervous system as more and more complicated life forms evolved.I rather prefer the approach of advancements using technology rather than writing with chalk on slate and swimming the Atlantic for the Paris vacation. How on Earth can we expect to take fish oil and do memory exercises and even move forward one order of magnitude in terms of data accessibility and cognitive abilities?