Flat ephys signal when loading data with read_openephys

[slew000]

Hello,

I'm using spikeinterface to load and visualise OpenEphys data before spike sorting, but I'm having issues with the visualisation. I'm loading my files using auxrec = si.read_openephys(folder_path=file_path), with the file_path being this open ephys folder:

When I try to plot the imported data using sw.plot_traces(auxrec, time_range=[0,10]), I can only see the TTL channel, but the ephys signal seems flat (I have checked in OE and there is data, it is not actually flat):

However, if I plot the data using using .get_traces() or if I apply auxrec.channel_slice(channel_ids=chan_ids), and I plot the data using the same functions, I can see the signal:

Does anyone have any idea on why the imported signal displays as flat?

Thanks a lot!

[alejoe91]

Hi @slew000

I think it's just a scaling issue in the visualization! If you try the `sw.plot_traces(auxrec, time_range=[0,10], channel_ids=chan_ids) you should get a similar plot :)

[slew000]

Hi @slew000

I think it's just a scaling issue in the visualization! If you try the `sw.plot_traces(auxrec, time_range=[0,10], channel_ids=chan_ids) you should get a similar plot :)

Hi Alejo,

Thanks, that worked! However, I don't think I fully understand the scaling. In the flat plot, if I zoom in or out, I still don't see anything (?), whereas the TTL signal seems fine. (For reference, I took out the TTL channels of the chan_ids)

Thanks!

[alejoe91]

I think that's simply because the ephys signals are in the uV scale, while the TTL signals are full range, so the events can be a few Volts