OE data conversion and filtering

[Alessandro Leparulo]

Good morning, everyone! 

I have a question about data conversion and filtering and sorry if this has already been asked but searching through the conversations, I only found two old posts from 2018.

I have recently started using Open Ephys for data acquisition again and am revising my Matlab analysis scripts. 

While rereading some literature, I found this: 

Okun M. Artefactual origin of biphasic cortical spike-LFP correlation. J Comput Neurosci. 2017 Feb;42(1):31-35. doi: 10.1007/s10827-016-0625-5. Epub 2016 Sep 14. PMID: 27629491; PMCID: PMC5250656.

In summary, the article discusses phase distortions, especially at low frequencies which are then reflected in the high frequencies/spikes, introduced by acquisition systems and how to correct them.

 

Is this correction performed by the new Matlab conversion toolbox?

Is this correction always necessary, even with the new hardware versions (I am referring to v.2.2 and 2.4) of Open Ephys?

Thanks!

Alessandro

[Josh Siegle]

Hi Alessandro,

This distortion results from the filtering properties of the Intan chip, which are used in all headstages compatible with the Open Ephys acquisition board. So it will be an issue for all acquisition boards, no matter what the version.

You don't need to do this correction unless you are explicitly analyzing coupling between the spikes and LFP (particularly by calculating a spike-triggered average LFP signal). The correction code is still available in this analysis-tools repo, we haven't ported it to the more recent open-ephys-matlab-tools package.

Best,

Josh

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