Tracking mouse gaze on screen clarifications

Technical
, , , , , ,
1

Hello everyone,
First of all thanks for the amazing dataset, it really is full of useful information.
I am working on the neuropixel data and I am trying to track the pupil movement of the mouse over the screen to compensate for the saccade when estimating the receptive fields of units. I noticed that through “session.get_screen_gaze_data()” (where session is “cache.get_session_data(<session_id>)” I am able to get the raw_screen_coordinates_x_cm and for y. However I was wondering a couple of things:

  • Are the raw screen coordinates found in the get screen gaze basically the coordinates of where on the screen the mouse looks at?

  • What is the reference point of these measurements. Are these measurements taken with respect to the centre of the monitor or one of its corners or even an external reference point?

  • How big is the screen? I have seen on the white paper it says width of 21.93 inch while on another thread on this forum it says 53.3 cm which are different. (By the way, the screen should be 1920x1200 even though the natural movies have a much lower resolution, am I correct?)

  • When you get the natural movie stimulus, what you obtain is what the mouse should have seen taking into account that the image on the screen was warped and that the mouse field of vision “warps it back” am I correct? So there is no need to apply a mask to the natural movie when estimating the receptive field since the return of the function get_natural_movie_one is effectively what the mouse sees?

I am sorry if I have asked so many questions, but I thank you in advance for your time and much appreciated consideration.

Pete

(PS: I know there is a question with a similar title asked already, but effectively there is no answer to the particular questions I am asking)

2

Hi Pete,

Thanks for the questions!

The raw screen coordinates are the position of the pupil on the monitor, and where mouse’s center of gaze is located. Because mice are not foveal animals, I would not say it is where the mouse “looks at”, but it is where the center of gaze is positioned.

These coordinates are relative to the center of the monitor, so (0,0) is in the center of the monitor, with positive values going to the right and to the top of the monitor.

Thanks for catching the discrepancies in our documentation. The monitor itself has a width of 21.93 inches, but this is the full monitor size. The actual display is smaller, 20.4 inches (51.8 cm). And yes, the monitor is 1920X1200 pixels even though the scenes and movies have different resolution, that is correct.

And yes, the natural movie template that you get from the SDK returns what the mouse sees.

Let us know if you have further questions!
Saskia

1 Like
3

Hi Saskia,

Thank you a lot for taking the time to answer all my questions. It’s all clear now, your reply helped me very much!

Kind regards,
Pete

1 Like