As an actual neuroscientist (PhD student, in a past life, now a googler), I would disagree with this part: > Inserting electrodes in the brain is the easy part.

As an actual neuroscientist (PhD student, in a past life, now a googler), I would disagree with this part: > Inserting electrodes in the brain is the easy part. The reason no one else has yet bothered with this level of miniaturization is because it won't be of much benefit until you can figure out a way to decode the signals reliably. I performed and analyzed multielectrode recordings not entirely different from the ones used by Neuralink (Neuronexus is the brand if you want to look it up). These were pretty much the state of the art as far as electrode density in vivo goes. And we would absolutely have loved to have higher density. We even went so far as trying to simulate higher density by moving the electrode array around with a microdrive and repeating the stimulus. I am quite sure the constraint is not on the demand for higher density arrays from scientists, it is more on the manufacturing side, the economics for further miniaturization are probably not there, in the absence of the Elon Musk cash spigot. I fully agree that many of the claims Neuralink are making are quite a ways off though.