Stimulus Channels

Stimulus Channels#

Stimulus view summarizes detected trigger channels and event structure used for epoching.

For execution steps, see Tutorial.

Subject-report stimulus view#

Stimulus channel overview

What is shown:

  • stimulus channel IDs (one channel per row on Y axis),

  • event IDs/types per channel,

  • event counts,

  • epoching context for event-based segmentation.

Why this view is critical#

Event integrity affects all epoch-dependent metrics (for example STD/PtP/ECG/EOG epoch summaries).

Use this panel to verify:

  • the expected trigger channels are present,

  • event IDs are plausible,

  • no obvious trigger sparsity or corruption is present.

QC implications#

  • missing or malformed trigger structure can force fixed-length epoch fallback,

  • task/run comparisons are less interpretable when event definitions differ,

  • trigger anomalies should be documented before downstream QC decisions.

When stimulus channels are unavailable or unreliable, MEGqc falls back to fixed-length epoching (configurable via use_fixed_length_epochs and fixed_epoch_duration in settings). The stimulus view helps identify whether event-based or fixed-length epoching was used.