Back to PLS HelpPosted on 09/04/20 13:24:40
Number of posts: 36
Greetings PLS/Baycrest community,
I have a study in which participants were stimulated at six separate cortical sites while undergoing EEG recording. In this same group of participants, multiple behavioural/cognitive tests were adminstered.
My question of interest is whether EEG data from perturbation of multiple cortical sites can better predict/correlate with the cognitive scores compared to perturbation of a single site only. From my readings, a multivariate analysis of my data might be best to incorporate the data from these six stimulation sites (which can be thought of as tasks conditions) together and relate them to behaviour.
Reading papers related to PLS (particularly this one https://www.sciencedirect.com/science/article/pii/S1053811910010074#bb0145), it seems as though behavioural PLS may be relevant to what I am trying to do. However, the text commonly refers to a single X matrix which makes me unsure if I have the right idea (in my head I'm thinking of six 'X' data matrices, one for each condition).
With my question in mind, is it something that can be investigated using PLS?
Thank you in advance for any comments or suggestions.
Best,
Paul
Replies:
Posted on 09/04/20 13:32:41
Number of posts: 394
Greetings PLS/Baycrest community,
I have a study in which participants were stimulated at six separate cortical sites while undergoing EEG recording. In this same group of participants, multiple behavioural/cognitive tests were adminstered.
My question of interest is whether EEG data from perturbation of multiple cortical sites can better predict/correlate with the cognitive scores compared to perturbation of a single site only. From my readings, a multivariate analysis of my data might be best to incorporate the data from these six stimulation sites (which can be thought of as tasks conditions) together and relate them to behaviour.
Reading papers related to PLS (particularly this one https://www.sciencedirect.com/science/article/pii/S1053811910010074#bb0145), it seems as though behavioural PLS may be relevant to what I am trying to do. However, the text commonly refers to a single X matrix which makes me unsure if I have the right idea (in my head I'm thinking of six 'X' data matrices, one for each condition).
With my question in mind, is it something that can be investigated using PLS?
Thank you in advance for any comments or suggestions.
Best,
Paul
Hi Paul,
If I understand the experiment, then 'yes' PLS can be used for your question. Each of the stimulation conditions would have a corresponding behavior (X) vector so you would comparing six correlation maps.
hope that helps
Randy
Posted on 09/04/20 18:16:00
Number of posts: 36
Hi Paul,
If I understand the experiment, then 'yes' PLS can be used for your question. Each of the stimulation conditions would have a corresponding behavior (X) vector so you would comparing six correlation maps.
hope that helps
Randy
Dear Dr. McIntosh,
thank you very much for the reply.
Sorry for the follow up, but what I am hoping to address is this: using data from perturbation of X cortical sites (e.g. left and right DLPFC) better predicts cognitive performance than using data from perurbation of X - 1 cortical sites (e.g. just left DLPFC). I was thinking of using the 'merge conditions' option to potentially address this. Maybe I am not understanding PLS correctly in thinking if it can answer this question?
Thank you again,
Paul
Posted on 09/05/20 08:34:48
Number of posts: 394
Dear Dr. McIntosh,
thank you very much for the reply.
Sorry for the follow up, but what I am hoping to address is this: using data from perturbation of X cortical sites (e.g. left and right DLPFC) better predicts cognitive performance than using data from perurbation of X - 1 cortical sites (e.g. just left DLPFC). I was thinking of using the 'merge conditions' option to potentially address this. Maybe I am not understanding PLS correctly in thinking if it can answer this question?
Thank you again,
Paul
Hi Paul,
I am not sure that you can combine conditions as if the two sites were stimulated at the same time. If I understand your question, you want to see if stimulating left and right together yields better prediction of cogntion that each site alone. From what you write, it seems you have data one for left stimulation and right stimulation, but not left and right together. Without such data, I don't see how you can address your question. Am I missing something?
Posted on 09/05/20 09:36:30
Number of posts: 36
Hi Paul,
I am not sure that you can combine conditions as if the two sites were stimulated at the same time. If I understand your question, you want to see if stimulating left and right together yields better prediction of cogntion that each site alone. From what you write, it seems you have data one for left stimulation and right stimulation, but not left and right together. Without such data, I don't see how you can address your question. Am I missing something?
Hi Dr. McIntosh,
what you say is correct. Each site was stimulated independently (and not at the same time). For example, the left DLPFC would be stimulated while EEG was concurently recorded, and then the right DLPFC aftwards was stimulated with EEG concurently recorded, meaning there are two separate EEG files, one for left DLPFC, and one for right DLPFC.
I was hoping to see if a combination of the EEG data collected from multiple sites better predicts cognition than data alone from either of the six sites alone. But from what you mentioned before, using Behaviour PLS, it would compare the six cortical sites (and their correlation maps) to see if one stimulated site better predicts cognition than the remaining others. If I am understanding correctly, this would not address the question if data from two sites (e.g. left and right DLPFC) better predicts cognitive performance than data alone from either site (e.g. left or right DLPFC).
Sorry for any confusion, but your insight is greatly appreciated.
All the best,
Paul
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