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How do you handle negative oxy-Hb and positive deoxy-Hb values?

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Eminent Member
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Hello everyone,

I have some negative oxy-Hb and positive deoxy-Hb values which I want to make sure I handle appropriately. Is it acceptable to include these in an ROI? Should these channels be removed? Or something else? Thanks in advance!


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Rob I am also getting some negative values for oxyhb. Are you working with children by any chance?

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@meredith  Hi Meredith! I am having negative HbO values and working with a peri-adolescent group.

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I wouldn't remove them just because they are negative. You need some justifiable reason and being negative doesn't strike me as justifiable.

Often times it can be a true deactivation. For instance, a channel over the medial PFC could go negative following a stimulus because of deactivation of the default mode network. This is something we have seen in a few studies now at BU. And historically speaking, this was anecdotally observed in fMRI studies ages ago and lead to the discovery of the default mode network.