Modeling Heart Period Responses

[Suzanne Estrada]

Hi Dominik,

Thank you so much for the help that you've already provided me related to GSR processing! I am also interested in using PsPM to process pulse data. After working with my own data and reading your 2016 paper on modeling event-related heart periods, I had a few questions about how you would recommend using the heart period data generated through PsPM:

1. Is there a response function that you would recommend using as the "default"? I am doing an auditory conditioning task that involves multiple different types of tones. Would it be reasonable in your opinion to use RF 2 given that it allowed for the discrimination of 85 dB tones, 65 dB tones, and Positive and Negative IAPS pictures? Alternatively, would you recommend performing a principal components analysis based on our own data?
2. I have been using GLM to analyze the heart period data. What do the values output by the GLM analysis represent? Do they represent the peak of the response function, an acceleration/deceleration value, or another value?

Thank you so much in advance for your help!

Best,
Suzy

[Dominik Bach]

Hi Suzanne

1. Phasic heart-period responses are not (yet) well characterised, both within and outside of the model-based approach. I would suggest to
2. use all basis functions that do not overlap with the next stimulus, but importantly, include all of them in the model even if you only plan to analyse a subset.
3. plot the observed responses using the tool functions extract segments and segment mean, to get an idea how well the PsPM will fit the data
4. GLM output of a model w/o derivatives represents, loosely speaking, the regression coefficient of a regression from observed data onto response function. Or in other words, it represents the amplitude of the part of the observed response that is explained by the response function. For heart period, this amplitude is expressed in units of heart period (changes) in milliseconds, i.e. positive values mean decelaration, negative values acceleration.

Hope this helps
Dominik