3 ms·

I used to work in a lab that did some single-neuron recording and some array-recording. We recorded from monkeys. The monkeys had to have a chamber surgery in o

I used to work in a lab that did some single-neuron recording and some array-recording. We recorded from monkeys. The monkeys had to have a chamber surgery in order for electrodes to be inserted into the brain. This article mentions that they'll be recording from many areas simultaneously. I would think this would mean multiple chamber surgeries in different areas. I know that these surgeries do damage to the monkeys. Could a monkey sustain so many chamber surgeries? What about other animals?

simonster 12y ago
Usually multi-shank arrays like the one depicted in the press release are chronic, so no chamber is necessary. Instead, they are implanted directly into the brain during surgery and wired to a port on the animal's head. There's still some risk, since one still has to remove the skull above the target site and also cut and resew the dura mater, but the skin can be sewed back together after implantation and the bone will eventually regenerate. Unlike in an acute preparation with a chamber, there is no exposed dura that needs to be cleaned regularly to prevent infection, and the electrodes are inserted just once instead of repeatedly. If the recording contacts are sufficiently dense, the total area of skull that needs to be removed to implant 1000 channels worth of arrays may actually be less than in a conventional two-chamber (maybe even single chamber) acute primate preparation. But we'll see.
- adamzerner 12y ago
  Very interesting, thanks for the explanation!
- kghose 12y ago
  The OP's point about damage still holds. After implanting the chronic arrays you have to wait about 3 weeks before recording (the area is silent). It is assumed that the responses are normal after that - and it seems so. But we have a lot of results from arrays that have no counterpart from single electrode recordings so we really don't know. You are basically jamming a pincushion into the cortex. Trauma is inevitable. The denser the array the more the damage (the more mass you are jamming into cortex). You most likely have a perturbed cortex that has recovered from damage. Is this the same as original intact cortex?
  - simonster 12y ago
    Yes, the typical caveats of putting things in the brain still apply. But I'm expecting that the increased density in these arrays will come mostly from putting multiple contacts on each shank rather than putting the shanks closer together, which may not produce any more damage than an ordinary Blackrock array.

simonster 12y ago

Usually multi-shank arrays like the one depicted in the press release are chronic, so no chamber is necessary. Instead, they are implanted directly into the brain during surgery and wired to a port on the animal's head. There's still some risk, since one still has to remove the skull above the target site and also cut and resew the dura mater, but the skin can be sewed back together after implantation and the bone will eventually regenerate. Unlike in an acute preparation with a chamber, there is no exposed dura that needs to be cleaned regularly to prevent infection, and the electrodes are inserted just once instead of repeatedly. If the recording contacts are sufficiently dense, the total area of skull that needs to be removed to implant 1000 channels worth of arrays may actually be less than in a conventional two-chamber (maybe even single chamber) acute primate preparation. But we'll see.

adamzerner 12y ago
Very interesting, thanks for the explanation!
kghose 12y ago
The OP's point about damage still holds. After implanting the chronic arrays you have to wait about 3 weeks before recording (the area is silent). It is assumed that the responses are normal after that - and it seems so. But we have a lot of results from arrays that have no counterpart from single electrode recordings so we really don't know. You are basically jamming a pincushion into the cortex. Trauma is inevitable. The denser the array the more the damage (the more mass you are jamming into cortex). You most likely have a perturbed cortex that has recovered from damage. Is this the same as original intact cortex?
- simonster 12y ago
  Yes, the typical caveats of putting things in the brain still apply. But I'm expecting that the increased density in these arrays will come mostly from putting multiple contacts on each shank rather than putting the shanks closer together, which may not produce any more damage than an ordinary Blackrock array.