7 ms·
EEG channels with low-cost PiEEG device
- brcmthrowaway 3y agoIs this how the Neuralink device works?
- _Microft 3y agoNeuraLink is using a specialized robot to surgically insert very thin electrodes into the brain. This device here uses good old wet or dry EEG electrodes that are touching the outside of the head (e.g. on an EEG cap).
- roughly 3y agoAs a bad analogy, I've heard the difference between EEG and implants described as pointing microphones at the outside of a building vs having them inside the room.
- hasmanean 3y agoWell at least you can tell if there’s a party going on in room 106.
- plastic-enjoyer 3y agoWell, EEG is more like undirected microphones that record the voices of several thousand people at the same time outside of a building, whereas implants are more like directed microphones inside the building that only record the voices of a few people...
- nextaccountic 3y agoIt's worth noting that if each electrode is thin enough to be placed in extracellular medium getting signals from several neurons around it, you can do some fairly simple signal processing to separate the signals of individual neurons. This is called spike sorting [0] (a "spike" is an impulse transmitted by a single neuron). So, continuing with the microphone analogy, with the right setup, recording a few voices is almost as good as recording each voice separately. It's not perfect because sometimes people talk over each other, and people distant from the mic may have muffed voices, and stuff like that. But generally speaking, we can roughly understand each individual people in a recording, because each people speak in a different way (and just like that, neurons spike in a different way). Here's some academic code that does this [1] (it has accompanying articles [2] [3]) (Random article found in Google, no affiliation). The first thing it does is removing the low frequency component of the signal (the LFP [4], that doesn't originate from any specific neuron), then it stores each individual spike waveform as a time series (a vector of N dimensions, where each dimension is the value of the signal at a moment in time), and then just does some k-means clustering to separate spikes in clusters, then assign each cluster to an individual neuron (by hypothesizing that each neuron likes to spike in a specific way which depends on its characteristics). This is all very vanilla / undergraduate stuff, and it's been done for more than 10 years [5] or perhaps even 20 years or more. Trouble is, with EEG all you have is essentially an average of the LFP over a large area; you don't get single-neuron spikes. So EEG fundamentally can't listen to each neuron individually. However it isn't right to simply throw away LFP information, and you can still do stuff with it. [0] http://www.scholarpedia.org/article/Spike_sorting http://www.scholarpedia.org/article/Spike_sorting [1] https://github.com/akcarsten/spike_sorting https://github.com/akcarsten/spike_sorting [2] https://towardsdatascience.com/using-signal-processing-to-extract-neural-events-in-python-964437dc7c0?gi=bf8f08a89753 https://towardsdatascience.com/using-signal-processing-to-ex... [3] https://towardsdatascience.com/whos-talking-using-k-means-clustering-to-sort-neural-events-in-python-e7a8a76f316 https://towardsdatascience.com/whos-talking-using-k-means-cl... [4] https://en.wikipedia.org/wiki/Local_field_potential https://en.wikipedia.org/wiki/Local_field_potential [5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3657693/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3657693/
- ron_87 3y agoSounds great! thank you, you seem to be good at this
- nextaccountic 3y agoNot really, I just took a couple of undergraduate courses in neuroscience, but I didn't major in it or anything. For a time I thought about doing research in this area, but I got sick of how the lab animals were treated. Take a look at this https://en.wikipedia.org/wiki/Remote_control_animal https://en.wikipedia.org/wiki/Remote_control_animal
- brcmthrowaway 3y agoHow does the neuralink get an advantage though, do neuron spike signals contain any information
- ron_87 3y agoof course not
- wpietri 3y agoI like the idea, but $350 plus a Pi plus getting electrodes is beyond my "impulse by to try it out" price for sure.
- ron_87 3y agoyes, hat electrodes + plus about 300 dollars
- y-curious 3y agoI work at a relatively unique EEG startup, and our single-patient-use EEG headbands cost a bit more than this project. That said, doing an EEG on yourself is a bit disappointing imo; You won't get much interesting output.
- m_kos 3y agoIf you are at liberty to share, how many channels and are the electrodes dry or wet?
- y-curious 3y agoSure :) (this is all publically available, fyi, no trade secrets here) 8 channel headband with individual gel packets for each electrode. You pop the gel packets and then you have wet electrodes! The company is called Ceribell; Happy to answer more questions if you have them. We do not sell to individuals, but if you're in the research space, I'm happy to get in touch.
- mt_ 3y agoWhat are good papers to get started on BCI in tandem with the recent advancements in Large Language Models?
- tbenst 3y agoOur preprint does exactly that :). https://arxiv.org/abs/2403.05583 https://arxiv.org/abs/2403.05583
- gorkish 3y agoThis seems as if it could be cool, but the board is $350 with a BoM of about 50 bucks. Considering the current nascent state of things, this doesn't really feel like a project on a successful path.
- ron_87 3y agowhy 50 ?
- _Microft 3y agoThe Elecrow page says that the analog front end used on the board is a ADS1299. The eight channel version of it is 60€+VAT on Digikey. The rest of the parts is most likely very cheap.
- ron_87 3y agoyes, but also ICs for Voltage! I use with the low noise. Also price for PCB board and for soldering and in my case also included software) But anyway I will try make price lower in the near future
- _Microft 3y agoThe BoM is of course only a small part of the cost and there is lots of work time and prototypes that need to be paid off by selling finished devices. I‘m sorry if that sounded like I thought that the price might be too high. Thanks for your efforts!
- ron_87 3y agoyou are very polite, thank you very much
- deleted 3y ago[deleted]
- gorkish 3y ago
- dmarto 3y agoThere is also the OpenEEG project[0], the boards are way cheaper (sub 100eur[1]) and also they are both open source and open hardware. [0] - https://openeeg.sourceforge.net/doc/index.html https://openeeg.sourceforge.net/doc/index.html [1] - https://www.olimex.com/Products/EEG/OpenEEG/ https://www.olimex.com/Products/EEG/OpenEEG/
- ron_87 3y agois is possible measure EEG with 8 bits ADC ?
- dmarto 3y agoWith an active electrode, it should be good enough. After all, we are talking about hobby-grade results. The Olimex ones are 10-bit (supporting both active and passive electrodes), while it's claimed[0] that 12-bit resolution is sufficient for EEG. However, it's worth noting that there are obvious advantages to the higher resolution. [0] https://www.biosemi.com/faq/24bitsystem.htm https://www.biosemi.com/faq/24bitsystem.htm
- ron_87 3y agoEEG in microvolts, if ADC 12 bits, then reference for ADC should be in millivolts
- mlyle 3y agoHe mentions active probes. Active probes have amplification. As his link makes clear, your ADC just needs enough resolution to measure the signal when the (amplified) offset voltages don't saturate it.
- ron_87 3y agoyes, I told about digital EEG device from this website. To clarify analog device, I need a little more time
- Kiboneu 3y ago
- QuantumG 3y agoIs someone maintaining a big list of BCIs somewhere? If you're going with extra-cranial hardware, I think the best available involves Microwave Brain Stimulation along with passive sensing methods like this. Unidirectional brain -> computer is neat but so long as the feedback is via sight or sound it's just another move-the-mouse alternative.
- xkcd-sucks 3y ago> , I think the best available involves [anything] Consider how long it took to start suspecting football and other low impact head trauma of causing CTE, and to start believing in CTE at all. Personally, with a phd in neurobiology and no real data besides gut feeling, I would not be comfortable with any system that wasn't thoroughly shown to be mostly harmless over several decades at least
- QuantumG 3y agoWhereas others take drugs made in bathtubs and cooked by idiots. The right to experiment on oneself is, for now, an advantage individuals have over corporate interests. You do you. I'm happy just seeing what kinds of stuff they make, for now, but if someone makes something cool, I'll buy the kit.
- ron_87 3y agoForgot to say, 8 channels now and 16 in the few months
- pedalpete 3y agoI was going to point to openBCI as another option, but the definitely are not a low-cost option. I don't remember spending this much on the Cyton board a few years ago. https://shop.openbci.com/collections/frontpage https://shop.openbci.com/collections/frontpage
- ron_87 3y agoyes, thank you!
- seeknotfind 3y agoAnyone recommend particular electrodes for this or have a good comparison with alternatives?
- ron_87 3y agodry electrodes Ag/AgCl (silver-silver chloride)
- lukeinator42 3y agoI recently discovered that you can attach an external electrode or two to a Muse headset: https://hackaday.io/project/162169-muse-eeg-headset-making-extra-electrode https://hackaday.io/project/162169-muse-eeg-headset-making-e.... This is a fairly cheap way to hack around with an EEG system that has four electrodes at the front and then an extra electrode you can place anywhere else you want. I think it would probably work pretty well for simple stuff like detecting P300s or SSVEP. But yeah you definitely get what you pay for with EEG. In the lab I'm in, we have a $150k EGI system and a $40k cognionics system and even the cognionics system is way more glitchy/low quality compared to the more expensive systems. Also, I wonder what happens safety/electrical noise-wise if you're plugging a raspberry pi into the wall? Generally, EEG systems are either battery-powered or use an isolation transformer. I wonder if it's best to power the pi with a battery.
- MPSimmons 3y agoWithout some serious fuse/filtering, I don't think I'd feel good about plugging it into the wall. It's easy enough to get a battery pack that can provide enough juice to run this for testing sessions, so why risk it, even if the risk is small?
- ron_87 3y agoonly from battery, thank for your message! for details write me here https://www.linkedin.com/in/ildar-rakhmatulin-262a66112/ https://www.linkedin.com/in/ildar-rakhmatulin-262a66112/