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Phase Locker Element

The Phase Locker element is a core component of the phase-locked stimulus presentation in EventIDE. The element runs an analys of online signal and triggers when a selected phase of signal ossilation (in desired frequency range) is met. The triggering of the element can be then used for an immediate presentation of stimulus or triggering other custom functions in an experiment.

Table of Contents [Hide/Show] Summary Properties Description Practical Use     Configuring for the first use     Configuring stimulus presentation with the Phase Locker element        Triggering stimulus presentation by 'Is Triggered' property        Triggering stimulus presentation by the Triggered snippet

Description ¶

Practical Use ¶

Configuring for the first use ¶

1. Add the element to an event that incorporates both signal processing and stimulus presentation. Such an event may have subevents that denote different stages of the stimulation procedure.
2. Browse to the element properties in the Properties panel.
3. Select the 'Input Signal' among those available in the current experiment.
4. Enter the actual sampling rate of the selected signal in the 'Sampling Rate' property.
5. Choose the target frequency range by defining the 'Frequency Range' property or select one of the presets via the 'Brain Wave Preset' property.
6. Enter the total length (in seconds) of a moving analysis window for signal visualization via the 'Analysis Window Length' property. The recommended value is about 4-10 periods of the central target oscillation. For instance, a 4-second window for the delta oscillations in the 0.5 - 1 Hz target range. There is no length restriction for the analysis window, apart from performance considerations.
7. Define the length of the right-most 'modeling' segment on the analysis window in periods of the central target oscillation. The signal in the modeling segment is used to build a future continuation of the current signal. The recommended period values are between 0.9 (faster detection) and 1.5 (more accurate detection).
8. Define the target phase (in degrees of the sine wave) for stimulus presentation via the 'Target Phase' property. If you plan to hit multiple phases, enter them with a '|' separator, for example, 90|180.
9. Enter the total measured latency (ms) of your signal recording into the 'Hardware Lag' property. The latency is the time needed to deliver the signal from hardware to EventIDE.
10. If you have a secondary monitor and use the EventIDE status screen at runtime, you can add the Phase Locker dashboard widget there via the status screen designer or XAML. The dashboard widget visualizes all stats of the phase-locking processing and allows changing of related parameters at runtime.
11. In most cases, other properties of the Phase Locker element can be used with the default values.
    

Configuring stimulus presentation with the Phase Locker element ¶

1. If you want to present a stimulus sequence locked to every target phase in a signal, set the 'Presentation Mode' property to 'Sequential Presentations'. If you plan to present a single stimulus at the first occurrence of the target phase, set 'Presentation Mode' to 'Single Presentation'. The single presentation mode can be resumed manually after each stimulus presentation.
2. Enable or disable the stimulus presentation with the 'Is Presenting' property. This property can be controlled at runtime either by scripts or by the dashboard widget of the element.
   

Phase locker element does not run stimulus presentaion by itself, but here are two easy ways for linked the element to trigger any stimulus presentation in EventIDE.

Triggering stimulus presentation by 'Is Triggered' property ¶

1. Add 2 subevents to the parent event of the Phase Locker element and name them 'Wait' and 'Stimulus'.
2. Add 2 event routes: the conditional route from the Wait event to the Stimulus event and a time route back from the Stimulus event to the Wait event.
3. Create a proxy variable for the 'Is Triggered' property of the Phase Locker element.
4. Use this proxy variable as a condition for the Wait -> Stimulus route, for instance, (IsTriggered==true).
5. Reset the IsTriggered proxy variable to 'false' in the After Onset snippet of the Wait event: IsTriggered=false;
6. Design your stimulus presentation in the Stimulus event. For example, you can add the Renderer element for a visual stimulus, the Wave Player for an audio stimulus, or a COM port element for sending a command to external hardware.
   

Triggering stimulus presentation by the Triggered snippet ¶

If you need more customization of stimulus presentation, you can use the Triggered snippet of the Phase Locker element to write your custom script there. The script will be invoked exactly at the time of the target phase, thus allowing you to run any stimulus presentation that you programmed. The script can read the current element properties, for example, 'Current Lock Phase' value when multiple target phases are used.



 

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