Hey fNIRS Community,

I'm using Homer3 to analyze my fNIRS data during a gross hand task while using a prosthetic (60 sec task) separated by rest (60 sec).  Interestingly, after using the GLM function in Homer3, I get a few channels with negative HbO2 values (i.e., classic HbO2 activation but completely negative values). I've attached a pdf of two channels with positive and negative HbO2 data as an example.  I was just curious if anyone else has seen this and if there is anything in literature that describes this.  I haven't seen this yet and hope to start a discussion on this here as I'm not sure what to make of it yet.  I appreciate any and all help with this.

Thanks,

Jordan