Mikkel Roald-ArbølAug 28, 2023
Nick Steinmetz
Introducing Neuropixels Ultra, a new probe with >10x site density: an implantable voltage camera capturing complete planar images of neurons' electrical fields in vivo! ⬆️ spike sorting yield, ⬆️ detection of small fields, and ⬆️ cell type identification.🧵
https://www.biorxiv.org/content/10.1101/2023.08.23.554527
Aug 28, 2023 at 5:32amWeb
Show threadNick SteinmetzAug 28, 2023
These probes capture incredible detail in the spatial structure of extracellular action potentials.
Show threadNick SteinmetzAug 28, 2023
Due to improved SNR and resolution, NP Ultra finds 3x more visually-responsive neurons in cortex. We developed a new sorting algorithm suited to NP Ultra called DARTsort with Paninski lab. The number of well-isolated neurons passing strict QCs was also improved by ~1.6x.
Show threadNick SteinmetzAug 28, 2023
We recorded across mouse brain regions and in three other species (monkey, lizard, and fish), finding everywhere a proportion of units with really small spatial “footprints”. These small units are especially enriched in areas densely packed with small neurons or axon fibers.
Show threadNick SteinmetzAug 28, 2023
Do small footprint units correspond to small interneuron cell types? In mouse visual cortex, no: we optotagged PV, SST, and VIP neurons but none had small footprints. And, the small units could be either excitatory or inhibitory in cross-correlations. They are likely axons there!
Show threadNick SteinmetzAug 28, 2023
Finally, can high-res NP Ultra recordings tell us more about neuron identity? Yes! We can decode cell type among the three optotagged classes ~75% correct, significantly better with NP Ultra than with NP 1.0.
Show threadNick SteinmetzAug 28, 2023
So, is this the device for your experiments? It’s ideal for experiments that: target dense nuclei or layers; need to detect small fields; or need cell type identification. The tradeoff is span: with all 384 sites packed so tightly, it covers ~300 µm compared to ~3 mm for NP 2.0.
Show threadNick SteinmetzAug 28, 2023

We’d love to hear your thoughts about this probe: would you use it for your scientific question? What do you like/dislike, and what would you change? A final production decision has not been made so your input here is critical.

Survey: https://forms.gle/xerfVKMcWjbGuwPk8

Show threadNick SteinmetzAug 28, 2023
I want to thank the huge team who participated - leading efforts from Zhiwen Ye and Andrew Shelton, major contributions from Jordan Shaker, Julien Boussard, and Jennifer Colonell, and fantastic work from the whole team!
Show threadNick SteinmetzAug 28, 2023
Last but not least, thank you to NIH Brain Initiative for funding this work - we appreciate the incredible support!
Show threadCarsen Stringer (she/her)Aug 31, 2023
@SteinmetzNeuro very cool Nick! Are the visual responses different in the units that didn't pass QC / are these units smaller (axon bundles) or are they something else? There are a lot of them and it would be neat if you could use them somehow to better understand visual responses in cortex
Show threadjonny (good kind)Aug 28, 2023
@SteinmetzNeuro
I keep looking at this gif and having to wipe the sweat off my brow
Show threadjonny (good kind)Aug 28, 2023
@SteinmetzNeuro
All ive got to say is holy shit
Show threadEl Duvelle NeuroAug 28, 2023

@SteinmetzNeuro super impressive work, and really nice thread! You might want to add some hashtags..

#Need2Read (this one is for me :) )