Hacker News Reader

Comment by bayesian_horse | Hacker News Reader

Is that actually an issue with current technology? Other implants, like bone replacements or simple screws for orthosynthesis, have higher sterility requirements than a brain implant might have, given that the brain has an easier time fighting infections. And they wouldn't usually implant the electrodes inside the brain but rather on the surface but below the skull.

And it's not completely necessary to have a physical connection to the outside. Again, I'm not sure what the current generation of BCI implants are doing, but technically it should be possible to completely close the wound (which may "only" be a small hole drilled into the skull), then use wireless transmission of power and information. Maybe that's not convenient enough right now to get the amount of data required, but it's more than theoretically possible.

View on HN

> given that the brain has an easier time fighting infections [than bones]

This doesn't match my understanding at all, but I'm not a medical professional. As far as I know, the brain relies heavily on isolation for protection. One function of the blood-brain barrier[0] is to prevent contamination of the central nervous system from pathogens and toxins. Bacterial meningitis is treatable with proper antibiotics, but still maintains a 10% mortality rate[1].

Additionally, simple mechanical implants (e.g. plates, screws, replacement joints) don't require interfacing with the body. They are often made of solid metals which are not bioreactive (e.g. titanium) or coated with bioresistant polymers[2].

[0] https://en.wikipedia.org/wiki/Blood%E2%80%93brain_barrier

[1] https://www.ncbi.nlm.nih.gov/books/NBK470351/

[2] https://en.wikipedia.org/wiki/Orthopedic_plate#Materials

My point was that there is a better access for the immune system in the brain. Not that you'd want any infection regardless.

Brain is an immune privileged organ so it is the opposite of your intuition. Get an infection into the brain and it is done.

> Immune-privileged sites include the central nervous system and brain, the eyes and the testes. Even foreign antigens accessing these tissues do not generally trigger immune responses.

https://www.sciencedirect.com/topics/biochemistry-genetics-a....

It's immune-privileged. There's plenty of access for immune-cells. Some infections like with Gondoplasma are quite survivable. By comparison, even a few bacterial cells in the wrong place during certain bone/joint replacement surgeries causes major issues.

No.

Any type of foreign body is inaccessible to the immune system, therefore prone to harbor sources of chronic infections, like bacterial biofilms.

"A significant proportion of medical implants become the focus of a device-related infection, difficult to eradicate because bacteria that cause these infections live in well-developed biofilms."

https://pubmed.ncbi.nlm.nih.gov/16353112/

No thanks, I don't want this anywhere near my central nervous system.

>>brain has an easier time fighting infections [vs bones]

While the brain has better blood supply than the hard outer parts of bones, which tends to accelerate healing, the brain also relies heavily on the blood-brain barrier to keep out many threats. Crossing the blood-brain barrier is a big deal, and we shouldn't assume automatically that it'll heal better.

>>it's not completely necessary to have a physical connection to the outside INDEED! This is completely key, as having a continuous surface breaking to just under the skin is a huge infection problem that must be continually cleaned and monitored, and having one right into the brain is a truly scary high-risk proposition. So successfully encapsulating and sealing it behind the blood-brain barrier is essential.

The problem is that this means wireless communication at a meaningful data rate, through the meninges encasing the brain, the scull, and scalp. This means power consumption, power supply, and necessary power supply replacement operations - into the brain, again.

The biology side is not trivial, even as we advance the electronics side, but I'm very much looking forward to these hurdles being overcome!

Electrodes would usually be mounted on the surface of the brain, outside the blood-brain barrier of course. That's plenty close enough for most purposes.

That'd help, but it is really not the same as fine electrodes talking to just one or a pair or triplet of neurons.

Once we're out there, we're either using an array and a lot of signal processing (sort of reverse synthetic aperture radar processing) to identify detailed signals, or just using aggregate signals.

In which case, why not use more gathering points and processing power and just go outside the scalp, avoiding infection problems entirely?

Reply on news.ycombinator.com