7T-visual-code

VPixx system on the 7T

This page provides information and some visual stimulus code for the 7T, notes for running the VPixx system on the dedicated machine with octave+Psychtoolbox under the ubuntu install.

Coding on macOS (`x86_64` version of `octave`)

General points

Asking a question, raising issues

What does it look like?

The setup is made up of a stack of hardware blocks (PROPixx, ResponsePixx, …) and there are two displays in the console room. One “mirrors” what the participant sees, the other can be used to keep an eye on the software running your experiments.

Setup in console rool Back of the VPixx setup The mirror system in situ

The front surface mirror is positioned to project the image (from the PROPixx box on the left towards the participant in the bore).

This mirror is required inside the scanner room to redirect the projected image onto the display screen, which is suspended from the ceiling.

Be very careful when moving the mirror into place and avoid touching the mirror surface itself (it is a front surface mirror, so doesn’t have a protective glass coating - finger prints can permanently damage it).

Switching on the projector

This is done is software - the power to the projector should always be on, so you can use a software call to wake/sleep the projector. (You may have to check a switch in the breaker/box in the equipment room to the left of the scanner room to make sure).

# either start the command line utility and follow meny into 
# "System commands" - by entering 0
vputil

# or straight away
vputil -ppx a # awake
vputil -ppx s # sleep

Make sure that you swith the projector off at the end of your experiment.

Sample code for testing

Triggering

Syncing stimulus timing with data acquisition on the scanner is a crucial aspect of running a successful functional MRI experiment.

The ResponsePixx blocks that are part of our setup allow for really precise timing at or better than the frame rate of display.

The BNC connector that sends the trigger from the scanner should go into pin 10 (Din10) on the ResponsePixx input box.

This is to make sure that there is no clash with the 10 possible inputs (from Din00 to Din09 for the two-paddle response box).

To-dos (some physical)

Initial vision experiment for UHFVIS project

Some notes and a scanning-readme for getting off the ground.

Documentation from VPixx website

Trying out a couple of provided demos to test digital IO and also ProPIXX display capabilities:

https://www.vpixx.com/manuals/psychtoolbox/html/intro.html

Contact

For now: denis.schluppeck@nottingham.ac.uk and you can also try the SPMIC Imaging for Neuroscience usergroup.