start time of lfp data

[bendichter]

For LFP, I am trying to handle if the probes were started at different times. I see a sampling rate, but no starting time. Contrast this with ephys.EphysRecording which has a recording_datetime field. For LFP, I see lfp_time_stamps, but the ones I can find start at 0, and it’s unclear whether this is time wrt the start of the LFP recording or the start of the session. recording_datetime  is the same for both probes in the example data, so that is consistent with the lfp time stamps being aligned, but it is unclear to me how it would be reflected in the data if the recordings started at different times. Would the lfp_time_stamps reflect this by having one of them not start at 0? Or would I be expected to infer the difference in start time by looking up the recording_datetime  from the same probe and session in the ephys.EphysRecording  table?

[kabilar]

Hi @bendichter,

For a given probe and session, the recording_datetime in ephys.EphysRecording is when the *.ap.meta file was created. See ephys.EphysRecording section and spikeglx.SpikeGLX section.

The lfp_time_stamps are with regard to the start of the LFP recording, and would thus always start at 0. See lfp_time_stamps calculation in ephys.LFP.

@ttngu207, can you please confirm?

[bendichter]

OK so I should look up the corresponding ephys.EphysRecording::recording_datetime for the start of LFP signal?

[kabilar]

Yes, I believe so. See lfp_time_stamps attribute comment.

My notes above were for SpikeGLX data. I am confirming the same is the case for OpenEphys data.