Sync Behavior - More TTLs sent than frames recorded

[hahnj]

I realized that when I record the TTLs that the miniscope sends for each recorded frame I always end up with more pulses/timestamps than frames recorded. The difference ranges from very few up to more than 100.

I couldn't find any correlation between the difference and recording length.
It is always more timestamps than frames.
The timestamp.dat file corresponds to the number of frames recorded.
The time difference between all TTL-timestamps recorded is the same (so I cannot exclude some timestamps just by looking at the difference).
=> It looks like the Miniscope sends the TTLs before starting the recording or is still sending TTLs after the Recording stopped (Or both).

Any ideas what could cause this or possible solutions?

 

[Daniel Aharoni]

Hi hahnj,
This is due to the computer's USB hardware not being able to keep up with the data being sent out of the Miniscope DAQ. There are a couple ways to correct for this and luckily David Tank's group just published a paper with a detailed supplement on how to deal with this. Here is a link to that info: https://www.cell.com/neuron/fulltext/S0896-6273(18)30852-3. Section B-2 in the supplemental materials.

Hope this helps.

[hahnj]

Dear Daniel,

Thanks, I will have a look.