MEG
Introduction
A typical MEG protocol involves the presentation of stimuli to the subject in different sensory modalities, the collection of subjects' responses, and the encoding of all these 'events' in the recorded data. In this section you will find all the details on the configuration of these systems in our MEG lab.
- Stimulus display. How visual or auditory stimuli are displayed.
- Response collection. Responses are collected through a 10-buttons system called fORP. Here you will find details on how fORP responses are encoded in the recorded data file and in the stimulation PC.
- Trigger encoding. Stimulus presentation and subject's responses represent events that have to be encoded as 'triggers' in the data file at the right times. Here you will learn how triggers are encoded in the Elekta MEG software, which is necessary to write a stimulus delivery program (see next point).
- Stimulus delivery. Triggers are delivered through the stimulation PC by a stimulus presentation program that you will have to implement, either in E prime or in PsychToolbox Matlab.
- Checking your triggers. Some tips on how to check your triggers before acquiring real data.
- Stimulus-trigger delay. How to measure the delay between the trigger time stamped on the data file and the actual time of stimulus presentation to the subject. This should be measured once for each protocol.