Skip to content
ContentLora

    Tip: press / anywhere to search.

    Explainer

    How scientists record brain activity

    Brain-computer interfaces and much of neuroscience depend on recording the brain's electrical signals, either from outside the head or with implanted electrodes.[1][2] Implants measure signals more directly and give faster, more precise control, but the risks of brain surgery mean only people with severe disabilities take part in implant trials.[3][4]

    Editor reviewedStrict sourcingUpdated Neuroscience and brain-computer interfacesLife sciencesHealth and medicine

    What is being recorded

    Brain cells talk to each other with tiny electrical pulses. Recording devices pick up those pulses, or related changes such as blood flow and oxygen levels in the brain.[1] Devices come in two families: wearable ones, such as a tight cap or headband, and implanted ones placed in, on or near the brain.[2]

    The closer a sensor is to the neurons, the clearer the signal. Implants measure signals directly from the brain, which makes them stronger and more precise than signals picked up through the skull.[3]

    Electrophysiological methods sit on a gradient of invasiveness. Scalp recordings capture summed activity through bone and skin. Surface arrays on the cortex record local field potentials from many neurons at once. Penetrating microelectrodes record spikes from single neurons or small groups.[5][6] Haemodynamic methods track blood flow and oxygenation rather than electrical activity.[1] GAO notes that implanted systems give faster, more precise device control than wearables because the signal is measured directly from the brain.[3]

    The main recording approaches

    Penetrating microelectrode arrays. The Utah array, a grid of tiny needles, was described in 1997 as a recording structure for brain-computer interfaces. It picks up small populations of neurons.[5] In 2006 a man with tetraplegia used a 96-electrode array in his motor cortex to move a cursor and open and close a prosthetic hand.[7] See utah-array.

    High-density silicon probes. Neuropixels probes put 960 recording sites on a single thin shank and digitize signals on the probe itself.[6][8] The 2.0 version has more than 5,000 sites and can follow the same neurons for more than two months in rodents.[9][10]

    Surface (ECoG-style) arrays. Thin films on the brain’s surface record from many sites without entering tissue. A 2023 UCSF study used high-density surface recordings to decode attempted speech at a median 78 words per minute.[11] Precision Neuroscience‘s Layer 7 film carries 1,024 electrodes.[12]

    Endovascular electrodes. Synchron‘s Stentrode reaches the brain through the blood vessels. In the SWITCH study it was delivered through the jugular vein to the superior sagittal sinus, with no open-brain surgery.[13]

    The trade-off: signal versus surgery

    Better signals usually mean more invasive surgery. Because brain surgery carries risks, implant trials are limited to people with severe disabilities, such as paralysis.[4] Implants can also change after surgery. Neuralink reported that some of the thin threads in its first participant pulled back out of the brain within weeks, which reduced the number of working electrodes.[14]

    Durability is the central engineering constraint. Neuralink’s thread retraction in its first PRIME participant cut the effective electrode count and performance until software was adapted.[14] Endovascular recording avoids craniotomy: SWITCH reported stable signal bandwidth and no vessel occlusion or device migration over 12 months, although it records from inside a vessel rather than from single neurons.[15] Paradromics reports four years of stable spike signal-to-noise in two sheep, an animal result that has not yet been shown in people.[16]

    From lab to clinic

    High-density probes are moving from animals into people. A 2022 study used a Neuropixels variant to record more than 200 single neurons at once in human cortex during neurosurgery.[17] Surface arrays are already in clinical use for short periods: Precision’s Layer 7 is cleared by FDA for implantation of up to 30 days.[18] As of December 2024, FDA had not authorized any implantable device for long-term BCI use.[19]

    What happens after the signal is recorded, decoding it into intent, is covered in the next explainer of this course, on how brain-computer interfaces work.

    Questions readers ask

    Why do brain implants work better than headsets?

    Implants measure signals directly from the brain, so the signals are stronger and more precise, and users can control devices faster and more accurately than with wearable systems.[3]

    Is there a brain implant that does not need open-brain surgery?

    Yes. The Stentrode is delivered by catheter through the jugular vein into a large vein over the brain; in its first study, four patients had no serious adverse events over 12 months.[13][15]

    How many neurons can one probe record?

    In 2017, two Neuropixels probes recorded more than 700 single neurons at once in a mouse, and a 2022 study recorded more than 200 single neurons at once in human cortex during surgery.[20][17]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      The signals BCIs measure can include the electrical charges brain cells use to communicate with each other, or changes in blood flow and oxygen levels in the brain. confirmedas of 2024-12-17

    2. [2]

      Implantable BCIs are usually placed in, on or near the surface of the brain, though one type is inserted through a vein in the neck; wearable BCIs take the form of a tight-fitting cap or headband. confirmedas of 2024-12-17

    3. [3]

      Implantable BCIs let users control devices faster and more precisely than wearable BCIs because they measure signals directly from the brain, making the signals stronger and more precise. confirmedas of 2024-12-17

    4. [4]

      The risks of brain surgery currently limit participation in implantable BCI clinical trials to people with severe disabilities. confirmedas of 2024-12-17

    5. [5]

      A 1997 study described the Utah Intracortical Electrode Array as a recording structure for brain-computer interfaces, recording from small populations of neurons with an average signal-to-noise ratio of 6 to 1. confirmedas of 1997-03-01

    6. [6]

      The original Neuropixels silicon probe, described in 2017, has 384 recording channels addressing 960 sites on a single 10-millimetre shank, and was designed because earlier extracellular probes recorded only a few dozen neurons per shank while calcium imaging could not reliably resolve individual spikes. confirmedas of 2017-11-08

    7. [7]

      In a 2006 Nature study, a man with tetraplegia used a 96-microelectrode array implanted in his primary motor cortex to move a computer cursor, open simulated e-mail and operate a prosthetic hand. confirmedas of 2006-07-13

    8. [8]

      Neuropixels probes filter, amplify, multiplex and digitize signals on the probe base, so digital data leave the probe directly. confirmedas of 2017-11-08

    9. [9]

      Neuropixels 2.0, published in 2021, has more than 5,000 sites, is miniaturized for chronic implants in small mammals, and gave high-quality long-term recordings in mice and rats in six laboratories. confirmedas of 2021-04-16

    10. [10]

      Improved site layout and new processing methods let Neuropixels 2.0 correct for brain movement and follow the same neurons for more than two months. confirmedas of 2021-04-16

    11. [11]

      A 2023 UCSF study used high-density recordings from the surface of the speech cortex to decode text at a median 78 words per minute with a median word error rate of 25 percent, and to drive a speaking facial avatar. confirmedas of 2023-08-23

    12. [12]

      Layer 7 is a thin-film surface electrode array with 1,024 electrodes on a device about the size of a postage stamp. confirmedas of 2026-10-10

    13. [13]

      The SWITCH study delivered Stentrode recording electrodes by catheter through the jugular vein to the superior sagittal sinus, avoiding open-brain surgery. confirmedas of 2023-03-01

    14. [15]

      In the first-in-human SWITCH study in Australia, four analysed patients completed 12 months of follow-up with no serious adverse events, no vessel occlusion or device migration, and each controlled a computer with the BCI. confirmedas of 2023-03-01

    15. [16]

      In October 2026 Paradromics reported four years of stable neural recording in two sheep implanted with cortical modules representative of its electrode technology, with no electrode-array migration observed. confirmedas of 2026-10-08

    16. [17]

      A 2022 study used a Neuropixels probe variant to record more than 200 well-isolated single neurons at once in human cortex during neurosurgery. confirmedas of 2022-02-01

    17. [18]

      In April 2025 Precision Neuroscience received FDA 510(k) clearance for its Layer 7 Cortical Interface, authorizing commercial use with implantation of up to 30 days. confirmedas of 2025-04-17

    18. [19]

      As of December 2024, FDA had not granted marketing authorization for any implantable device for BCI use. confirmedas of 2024-12-17

    19. [20]

      Using two Neuropixels probes, researchers recorded more than 700 well-isolated single neurons simultaneously from five brain structures in an awake mouse. confirmedas of 2017-11-08

    Revision history (1)
    1. Page created.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "How scientists record brain activity." ContentLora, updated Oct 10, 2026. https://contentlora.com/explain/how-neural-recording-works

    Spotted an error? Suggest a correction or emailcorrections@contentlora.com.

    Keep exploring

    ☰ Contents