Artifact cleaning with SSP
It is very common to have portions of the recordings heavily contaminated by events coming from the subject (eye blinks, movements, heartbeats, teeth clenching, implanted stimulators...) or from the environment (stimulation equipment, elevators, cars, trains, building vibrations...). Some of them are well defined, reproducible, short and frequent, and can be removed efficiently using Signal Space Projections (SSP). The purpose of this tutorial is to introduce this technique to correct for the cardiac and ocular artifacts.
For this tutorial, we are going to use the protocol created in the previous tutorial ?Review continuous recordings and edit markers. If you have not followed this tutorial yet, please do it now.
Signal Space Projections
Introduction to the method
Identifying the artifact
The first step for this method is to identify a large number of examples of the artifact.
Manual marking
Select the protocol TutorialRaw created in the previous tutorial, and select the "Functional data" view (second button in the toolbar on top of the database explorer).
- Double-click on the continuous recordings ("Link to raw file") to open the MEG recordings.
Right-click on the continuous recordings again > Misc > Display time series.