# Why does optogenetics not mean that perfect brain-computer interfaces are possible?

There have been multiple articles and videos circulating on the Internet claiming that optogenetics has made it possible to have perfect input/output to the brain from a computer. This is obviously false or someone would be making a lot of money selling this.

Consequently, I'm curious as to why this is false. Why does having the ability to fire and read the firing information off of individual neurons not imply that a seamless human-computer interface is possible? I'm assuming that this has something to do with the limits of the processing power of our brain and the limits of neuro-plasticity, but my experience in this domain is limited.

If this question is too broad (and I think it is), it can be reframed as a request for references. What current research is being done on this problem? What are the current approaches? Who is working on it? Are there any publications that nicely describe the progress in this (hypothetical) domain?

-
I am by no means an expert in optigenetics, but I have worked with photolytic uncaging of neurotransmitters in vivo. When the Wired article says That is to say, they insert the new gene into every neuron in that area, indiscriminately. But because of the promoter, the gene will only turn on in one type of neuron. All the other neurons will ignore it., they are referring to what may be dozens to hundreds of cell bodies and thousands of fibers of passage (white matter tracts) in that cubic millimeter. –  Chuck Sherrington Feb 27 at 3:51
To guarantee that you hit upon a transfected neuron and have no light leakage to the surrounding (transfected) cells would be quite a feat, and I don't think that the field is ready for that level of specificity quite yet. It's a great question, btw, just saying that some of it is probably more hyped up than anything that's actually possible right now. –  Chuck Sherrington Feb 27 at 3:53
For the record, we have a pretty amazing, evolutionarily-honed brain-computer interface going on already, with this eyes/hands combo thing. Anything hacked together using optogenetics would still be thousands of year behind, surely? Disclaimer: All I know about optogenetics I learned from a single Ted talk. Disclaimer: I know this is in no way helpful. Sorry. –  Eoin Feb 27 at 16:00