Millisecond Event Markers for Movement Research

The problem

A medical center’s human performance lab studies how the brain plans and controls movement. Their experiments pair an ankle robot and a reaching task with EEG recording, and the recording is only useful if every event is marked at the moment it happens: a cue appearing, a hand lifting off a button, a target being reached.

They needed tools to do that reliably, and they wanted them built so the next study could reuse them instead of starting over.

What we built

A signal-to-trigger router. The ankle robot puts out up to 16 analog signals. The router watches each one and sends a digital trigger to the EEG amplifier as soon as a signal crosses its threshold, within a few milliseconds. Researchers pick which signal drives which trigger line and set each threshold on screen. The tool prevents two signals from sharing a line and remembers the setup between sessions. It runs on its own, and it was designed to drop into a larger application later.

A study runner for reaching and expectancy experiments. The operator runs the session from one screen (start, pause, stop, choose the study, set the number of trials) while the participant sees only the cues on a second screen. Each trial steps through a timed sequence: rest, a red or green signal, then “go”. Every image change sends its own marker to the EEG the moment it appears.

Display times and the pauses between them vary randomly within set limits, so participants can’t anticipate the next cue. In the reaching study, red and green are shuffled evenly across the session. Separate loops watch the hand-rest button and an optical sensor at the target, so the moment a hand lifts off and the moment it arrives are marked too.

The result

The lab got consistent, precise event timing without hand-wiring each experiment. The timing logic lives in one shared component, so every display time and pause works the same way, and later studies can build on it rather than starting from scratch.