Hyperscanning

Hyperscanning is the simultaneous recording of EEG from two or more subjects, so their brain activity can be compared under shared events and experimental conditions. This article covers the hardware/software setup and two methods for keeping every subject's recording synchronized in time: LSL streaming (Option 1) and a TTL Trigger Adapter (Option 2).

Materials / Devices / Software

• Enobio device (1 per subject)

• Computer with NIC installed (1 per subject)

• Option 1 only: an LSL-compatible receiving application capable of receiving multiple streams and saving synchronized data (e.g., LabRecorder)

• Option 2 only: Neuroelectrics TTL Trigger Adapter (1 per device)

Step-by-step guide

1. Confirm hardware readiness

Set up one Enobio device and one computer running NIC for each subject in the session.

2. Choose a synchronization method

Decide between LSL streaming (Option 1) or a TTL Trigger Adapter (Option 2) to keep every subject's recording synchronized in time.

• Both methods correct for timing differences between the separate computers' clocks — choose based on what your analysis workflow already supports (LSL streams vs. hardware trigger markers).

3. Option 1 (LSL) — Install a receiving application

On one computer, install an LSL-compatible application that can receive multiple streams and save synchronized data.

• Neuroelectrics does not require a specific LSL client — any LSL-compatible application that can receive and save multiple synchronized streams will work (e.g., LabRecorder).

4. Option 1 (LSL) — Connect all computers to the same network

Put every subject's NIC computer and the LSL client computer on the same local network.

• All computers must be able to reach the LSL client computer for their streams to be discovered.

5. Option 1 (LSL) — Enable LSL streaming in NIC

On each subject's computer, turn on NIC's LSL data output before starting the session.

• The exact menu location can vary by NIC version — confirm the output is active before recording.

6. Option 1 (LSL) — Confirm every stream is received

Open the LSL client and check that a stream appears for each connected subject and is actively receiving data.

• If a subject's stream doesn't appear, check that computer's network connection and that LSL output is enabled.

7. Option 1 (LSL) — Record and confirm synchronization

Start the session, deliver your planned events and markers, then check the result once finished.

• The saved file should contain synchronized LSL timestamps across every subject's stream — this confirms the recording is properly synchronized.

8. Option 2 (TTL) — Connect a TTL Trigger Adapter to every device

Attach one Neuroelectrics TTL Trigger Adapter to each subject's Enobio device.

9. Option 2 (TTL) — Reserve a channel for the trigger signal

On each device, choose one EEG channel to record the trigger pulses.

• Neuroelectrics does not mandate a specific channel. Using the same channel index on every device makes cross-subject comparison simpler, but the choice is yours.

10. Option 2 (TTL) — Set your sync-pulse interval

Decide how often to send the TTL sync signal during the recording, based on how much clock drift your analysis can tolerate.

• There is no Neuroelectrics-recommended interval. The longer the interval, the more clock drift accumulates between corrections — set this according to your own protocol's timing requirements.

11. Option 2 (TTL) — Send the sync signal throughout the recording

Send the TTL pulse to all adapters at your chosen interval for the full duration of the session.

12. Option 2 (TTL) — Confirm synchronization

After recording, check the reserved channel in every subject's file.

• The trigger pulse should appear as a marker/event on that channel in every subject's recording at the same relative time — this confirms all devices received the signal simultaneously.