A new generation of miniature recording probes can track the same neurons inside tiny mouse brains over weeks — and even months. The new probes build on the success of the original Neuropixels probes released in 2017 and currently used in more than 400 labs. Neuropixels 2.0 are much smaller — about a third the size of their predecessors. They’re designed to record the electrical activity from more individual neurons and have the unique ability to track this activity over extended time periods. That makes them especially useful for studying long-term phenomena like learning and memory in small animals such as mice, the authors state in the latest issue of Science.

Measuring the dynamics of neural processing in detail requires following the spiking of thousands of individual neurons in the brain, not only over milliseconds but also over months.

Tracking the same neuron over time has been an ongoing challenge, because brains move a little bit whenever animals move. To address this issue, an international consortium of scientists developed a new generation of probes: Neurpixels 2.0.

They added in many more recording sites and moved them closer together. Like positioning many microphones around a crowded room, the design change makes it more likely that if a neuron jiggles out of reach of one recording site, it’ll still be picked up by a neighboring one.

And while the original Neuropixels probes — developed in 2017 — have just one narrow filament that enters the brain, the new version has four. That means the recording sites are distributed over a wider area, allowing for more efficient recording in many important brain areas, especially thin layers within the brain.

Neuropixels 2.0’s advances come from several key innovations. The scientists and engineers found ways to shrink the tool without losing recording capacity. They developed new ways to process the data and made strategic changes to the layout of the probes to make them better suited to certain tasks. Now, using Neuropixels 2.0 probes, researchers can simultaneously capture the activity of thousands of neurons in animals’ brains, and follow many of those neurons over time.

“Though we are not in a race with Neuralink [the company owned by Elon Musk], we observed that our new probes can record from over 6,000 recording sites — more than twice as many as any other available technology,” says Cagatay Aydin, postdoctoral scientist in the Haesler lab at NERF.

“We have also developed 3D-printable fixtures which facilitate the broad use of Neuropixels probes in a wide variety of experiments in freely moving mice, including models of brain disease.”

The probes are produced by imec, the nonprofit nano-electronics research center in Leuven, Belgium. Prototypes of the latest version are currently being tested by neuroscientists in labs across the world, and being tweaked and fine-tuned in response to users’ experiences. The consortium hopes that the probes will be ready for more widespread distribution in 2022.

The Neuropixels 2.0 consortium is led by Tim Harris at the Howard Hughes Medical Institute’s Janelia Research Campus, and includes scientists at University College London (UCL), at the Norwegian University for Science and Technology (NTNU) in Trondheim, Norway, at Neuroelectronics Research Flanders (NERF) in Leuven, Belgium, and at the Champalimaud Centre for the Unknown in Lisbon, Portugal.

Read the publication: Steinmetz, Aydin, Lebedeva, Okun, Pachitariu et al. 2021 (Science) Neuropixels 2.0: A miniaturized high-density probe for stable, long-term brain recordings

[Source: NERF]