I am running a frequency tagging study. The paradigm involves flashing visual stimuli on the screen at 2.5 & 3.16Hz to induce periodic neural responses. I've attached the grand averaged frequency spectrum showing the responses to our stimulation (fundamentals & harmonics highlighted) as well as peaks completely unrelated to our stimulation (unhighlighted). The source appears to be at 1Hz with the rest being its harmonics. I am not sure where this could be coming from as it doesn't align with our stimulation.
I have also included the topography of this 1Hz response which does not look visually based. It looks like it is right above CMS/DRL. Is it possible that something in the hardware is causing this?
Sidenote: there is an additional trigger in some of my files '4', that I did not code into the study. Unsure if this could be related.
- topo.JPG (39.29 KiB) Viewed 19261 times
- freqspect.JPG (47.46 KiB) Viewed 19261 times
Anna