4 ms·

7 millimeters deep is staggering. Holy crap! Just a few years ago I remember being very impressed by 500 microns. I am curious to see how well this is tolera

7 millimeters deep is staggering. Holy crap! Just a few years ago I remember being very impressed by 500 microns. I am curious to see how well this is tolerated in the long term. It is possible to damage tissues with very intense light, especially over time, but there are ways around this like 2-photon.

caycep 6y ago
I am just a interested observer - I remember the issue w/ the old viral vectors were concern re longevity of the cells, i.e. the optogenetically active ones you could do experiments on for several weeks, but then they'd poop out and die off for some reason, but this was just word of mouth chitchat with a postdoc who was working on this. Not sure if this was because of the light intensity or that mutating the cell with channelrhodopsin just made it weaker in general.... granted, not sure how intense of a light you'd need; I'd think the channelrhodopsins activate w/ just a few photons at the right wavelength... Coming from the clinical/Parkinsons' disease world, if someone made a stable viral vector specific for the basal ganglia though, that would certainly help w/ one of the biggest problems of clinical DBS - after 30 years of doing this, the biggest biggest biggest problem in whether the implant will work or not is still the +/- 2mm accuracy of the stereotactic frame implanting the electrode...(no matter what surgeons/stereotactic engineers claim...)
- hprotagonist 6y ago
  supplimentary figure 4 has data at +7 months.
tbenst 6y ago
Great question! See the supplementary note on tissue heating: https://web.stanford.edu/group/dlab/media/papers/chenNBT2020supp.pdf https://web.stanford.edu/group/dlab/media/papers/chenNBT2020...
- hprotagonist 6y ago
  that is properly impressive. cheers to the team for sure! I have done a little bit of corticofugal recording where we'd stimulate thalamus and record from cortex, and i was impressed enough at that. This opens up whole new frontiers in the game, though.
blovescoffee 6y ago
I'm almost completely unfamiliar with brain science. Could you explain the basic idea of what they're signalling 7mm deep? The brain is a good deal larger than 7mm, so are they just targeting certain areas towards the surface of the brain?
- deleted 6y ago
  [deleted]
- hprotagonist 6y ago
  more or less, all the "compute" stuff is towards the surface of the brain. The last time I did any of this work, in about 2017, 500 um was considered "deep brain" for optical stimulation. This is an order of magnitude deeper in one shot.

caycep 6y ago

I am just a interested observer - I remember the issue w/ the old viral vectors were concern re longevity of the cells, i.e. the optogenetically active ones you could do experiments on for several weeks, but then they'd poop out and die off for some reason, but this was just word of mouth chitchat with a postdoc who was working on this. Not sure if this was because of the light intensity or that mutating the cell with channelrhodopsin just made it weaker in general.... granted, not sure how intense of a light you'd need; I'd think the channelrhodopsins activate w/ just a few photons at the right wavelength... Coming from the clinical/Parkinsons' disease world, if someone made a stable viral vector specific for the basal ganglia though, that would certainly help w/ one of the biggest problems of clinical DBS - after 30 years of doing this, the biggest biggest biggest problem in whether the implant will work or not is still the +/- 2mm accuracy of the stereotactic frame implanting the electrode...(no matter what surgeons/stereotactic engineers claim...)

hprotagonist 6y ago
supplimentary figure 4 has data at +7 months.

tbenst 6y ago

Great question! See the supplementary note on tissue heating: https://web.stanford.edu/group/dlab/media/papers/chenNBT2020supp.pdf https://web.stanford.edu/group/dlab/media/papers/chenNBT2020...

hprotagonist 6y ago
that is properly impressive. cheers to the team for sure! I have done a little bit of corticofugal recording where we'd stimulate thalamus and record from cortex, and i was impressed enough at that. This opens up whole new frontiers in the game, though.

blovescoffee 6y ago

I'm almost completely unfamiliar with brain science. Could you explain the basic idea of what they're signalling 7mm deep? The brain is a good deal larger than 7mm, so are they just targeting certain areas towards the surface of the brain?

deleted 6y ago
[deleted]
hprotagonist 6y ago
more or less, all the "compute" stuff is towards the surface of the brain. The last time I did any of this work, in about 2017, 500 um was considered "deep brain" for optical stimulation. This is an order of magnitude deeper in one shot.