As I am new to PsPM, I have a few questions that I would greatly appreciate your insights on! I am collecting skin conductance data through BioPac to measure habituation to a 1050ms tone. One trial consists of a 1050ms tone and a variable 10-to-20 second inter-trial interval. Given that we are interested in habituation across 20 trials, we would be interested in the trial-level data to understand how SCR changes at each trial, so we have been using DCM.
In BioPac's Acqknowledge software, we set up an event marker channel that marks the onset of the tone. Is there a way to use the event marker channel when running the DCM model? If we use event markers, is there a way to specify a 1-4 second response window following the stimulus?
What counts as a "short stimulus" for DCM? In the FAQ page, it states that "if you only analyse SCR evoked by short stimulus – don’t use DCM." Would a 1050ms tone with a 10-20 second ITI be too short?
Is there a way to extract the peak value of the SCR using the DCM model? My understanding is that PsPM provides the area under the SCR curve, but we would also be interested in the peak value of the SCR if that is possible.
Thank you so much in advance, and please let me know if there is any additional information I can provide. I can also share a sample data file if that will be useful in any way.
All the best,
Suzy Estrada
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if you are interested in the evoked SCR to the tone, I think a GLM should give you the answer. The tones are short enough to count as "short", i.e. they are as long as most of the stimuli used to develop the SCRF (see Bach et al. 2010 Int J Psychophysiology https://www.ncbi.nlm.nih.gov/pubmed/20093150).
To look at habituation, you can either model each event as a "condition" in the GLM, which will give you single-trial estimates. Or you model all events in one "condition" and add a parametric modulator for linear, quadratic, or whatever you want, habituation.
However, if you choose DCM, then the time window you want to model is the time window during which sudomotor nerve activity is elicited - presumably during the stimulus, i.e. 0-1.05 s after stimulus onset. This is not the time window of the ensuing SCR. Note that DCM cannot be set up with event markers - it needs timings in seconds. You can use matlab scripting to extract the event markers from the PsPM file and construct a timings file. If you choose GLM, then the event markers can be used.
PsPM does not give you the AUC of the response, but instead the amplitude of the underlying sudomotor burst. PsPM does not give you access to peak-to-trough measures through the GUI (although there is a function in the 'backroom' folder doing this, but with no support from our side).
Hope this helps
Dominik
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi Dominik,
As I am new to PsPM, I have a few questions that I would greatly appreciate your insights on! I am collecting skin conductance data through BioPac to measure habituation to a 1050ms tone. One trial consists of a 1050ms tone and a variable 10-to-20 second inter-trial interval. Given that we are interested in habituation across 20 trials, we would be interested in the trial-level data to understand how SCR changes at each trial, so we have been using DCM.
In BioPac's Acqknowledge software, we set up an event marker channel that marks the onset of the tone. Is there a way to use the event marker channel when running the DCM model? If we use event markers, is there a way to specify a 1-4 second response window following the stimulus?
What counts as a "short stimulus" for DCM? In the FAQ page, it states that "if you only analyse SCR evoked by short stimulus – don’t use DCM." Would a 1050ms tone with a 10-20 second ITI be too short?
Is there a way to extract the peak value of the SCR using the DCM model? My understanding is that PsPM provides the area under the SCR curve, but we would also be interested in the peak value of the SCR if that is possible.
Thank you so much in advance, and please let me know if there is any additional information I can provide. I can also share a sample data file if that will be useful in any way.
All the best,
Suzy Estrada
Hi Suzy
if you are interested in the evoked SCR to the tone, I think a GLM should give you the answer. The tones are short enough to count as "short", i.e. they are as long as most of the stimuli used to develop the SCRF (see Bach et al. 2010 Int J Psychophysiology https://www.ncbi.nlm.nih.gov/pubmed/20093150).
To look at habituation, you can either model each event as a "condition" in the GLM, which will give you single-trial estimates. Or you model all events in one "condition" and add a parametric modulator for linear, quadratic, or whatever you want, habituation.
However, if you choose DCM, then the time window you want to model is the time window during which sudomotor nerve activity is elicited - presumably during the stimulus, i.e. 0-1.05 s after stimulus onset. This is not the time window of the ensuing SCR. Note that DCM cannot be set up with event markers - it needs timings in seconds. You can use matlab scripting to extract the event markers from the PsPM file and construct a timings file. If you choose GLM, then the event markers can be used.
PsPM does not give you the AUC of the response, but instead the amplitude of the underlying sudomotor burst. PsPM does not give you access to peak-to-trough measures through the GUI (although there is a function in the 'backroom' folder doing this, but with no support from our side).
Hope this helps
Dominik