Trigger Module

The Trigger module allows you to display visual stimuli and send trigger signals to your data acquisition interfaces during experiments. When you add the Trigger module, a configuration widget appears in the scrollable area where you can load a JSON configuration file that defines the trigger sequence. An example can be found under acquisitions/acquisition_config.json in the BioGUI repository.

Configuration

The trigger configuration is defined via a JSON file with the following structure:

{
  "triggers": {
    "Open Hand": "open_hand.png",
    "Close Hand": "close_hand.png"
  },
  "nReps": 5,
  "durationTrigger": 2000,
  "durationStart": 1000,
  "durationRest": 3000,
  "imageFolder": "/path/to/images"
}

Parameters

• triggers: Dictionary mapping trigger labels to image filenames
• nReps: Number of repetitions for each trigger
• durationTrigger: Duration (in milliseconds) for which each stimulus is displayed
• durationStart: Initial delay (in milliseconds) before the first trigger
• durationRest: Duration (in milliseconds) of rest periods between triggers with countdown
• imageFolder: Path to the folder containing the stimulus images

How It Works

1. When streaming starts, a viewer window opens displaying "START"
2. After durationStart milliseconds, the trigger sequence begins
3. For each trigger (repeated nReps times):
4. The stimulus is displayed as an image
5. A trigger signal is sent to all streaming controllers
6. After durationTrigger milliseconds, the rest period begins
7. During rest, a countdown is displayed showing the upcoming stimulus label
8. Triggers are set to 0 during rest periods
9. When all triggers are complete, the sequence stops

Usage Tips

• Images should be in PNG or JPG format
• If an image file is missing, the trigger label is displayed instead
• The countdown helps subjects prepare for the upcoming stimulus
• The viewer window can be closed to stop the trigger sequence early