GLM definition from multiple marker channels

[dominikbach]

We have created a new function to combine marker channels such that they can be used for GLM definition.

Timing of events in a GLM can be defined in time units (seconds or samples) relative to data file start, or in terms of markers contained in the data file.

For the latter case there are two options:

1. Define an index of the markers that belong to a certain condition, i. e. onsets{1} = [1,3,7];
2. Define the marker values that belong to a certain condition.

Option 2 is useful if the recording equipment allows storing different marker values for different event types. Some recording systems, however, allow binary markers only. In such cases, some researchers store markers for different types of events in separate channels.

From PsPM 6.2 and in the current development version, you can now use multiple marker channels to define GLM timing:

1. Combine all marker channels into one, using the respective preprocessing function. The channel index will become the marker value in the combined channel (i. e. every marker in the first selected marker channel will have value "1" in the new channel, etc). There is an option to retain or to delete the binary old marker channels.
2. Use the new marker channel to define a GLM by marker values.