[blauwbilgorgel]

This will be the first of this scale. On both those sites the most channels I could find was 64. This program is planning 10.000 channels for unprecedented resolution and scale.

Since 16 channels is enough to predict if a subject is looking at a face or not, it is exciting to research what this large-scale system is going to be capable of. Next to neuroscience, it could help with healthcare (research into dementia, epilepsy and schizophrenia).

[simonster]

The NeuroNexus Matrix array can be configured with up to 256 contacts. It's basically a Utah-style array with many shanks arranged in a rectangular grid. The difference from the standard Blackrock Utah array is that each of those shanks has multiple contacts along it. This is their newest product and you can buy it now, although I have no idea how well it actually works.

This technology is in principle extensible to much larger channel counts, if you increase the size of the array, the density of the shanks, and/or the density of the recording sites along each shank. I know that the Boyden lab at MIT has been working on this with the goal of simultaneously recording from >1000 sites. I'm not sure if they've met that goal yet, but they've been presenting on their progress at the annual Society for Neuroscience meeting since at least 2012.

One problem with standard microelectrode array technology is that it only works for targeting a small proportion of brain areas. You can only record from regions on the surface of the brain. Structures in sulci (folds) are difficult to reach because you'd have to pull apart the sulcus to insert the array, and many sulci contain blood vessels that will be ruptured if you do that. Targeting deeper structures like the thalamus (probably the most interesting target for schizophrenia) is intractable with this technology at least in primate brains because the electrode shanks have to penetrate a couple centimeters into the brain. Even if you could engineer an array with long enough shanks and manage to insert it without destroying it, you might do so much damage to brain tissue between the surface and the target that the resulting data would not reflect normal brain function.

[marvin]

The article wasn't clear on this, what is a "channel" in this sense? What is actually measured, from a physical perspective?

[simonster]

A "channel" usually means an individual contact on the device from which you can record a signal. A single channel may record "spikes" (action potentials) from dozens of neurons, but of those typically only 0-3 are distinguishable, depending on how close the electrode is to the neurons and how close the spike shapes are to each other. With ordinary metal electrodes, one can usually isolate action potentials from an average of 1-1.5 neurons per electrode.

However, not all channels are created equal. High channel count arrays typically have high contact densities. If the contacts are very close to each other (<100 microns or so), adjacent channels may record signals from the same neurons. I'm not entirely sure how this will affect the actual number of neurons one can isolate, but I'm eager to see. The contacts will record signals from fewer neurons than if the density were lower, but the increased density may make it possible to isolate signals that would otherwise be lost to noise, and will certainly make the process of determining which action potentials came from which neurons simpler.