Differences

This shows you the differences between two versions of the page.

--- stimulus-presentation [2023/03/28 14:28] – [How to sync stimuli with scanner acquisition] jonas
+++ stimulus-presentation [2025/03/27 16:37] (current) – carl
@@ Line 1: / Line 1: @@
 ===== Stimulus Presentation =====
-**Back projection system, using a multimedia projector and a perspex screen viewed by a mirror mounted on the headcoil.**
+==== Stimulus PC ====
+We now have a new stimulus PC in the MRI control room, which runs Windows X and Ubuntu X. Installed software on the Windows partition include: Matlab XXX, Psychophysics Toolbox XXXX, Presentation version XXXX, and PsychoPy.
+==== How to sync stimuli with scanner acquisition ====
+The scanner sends out a pulse at the onset of every EPI volume acquisition. This pulse is converted to a simulated mouse click through the special mouse connected to the Siemens PC (ask Ari for help identifying it). To use this as a trigger for your stimulus, simply include code to detect a mouse click in your stimulus code. **Please note:** The mouse may not be detected by your stimulus PC until it sends a signal - in some cases this can cause the first trigger from the scanner to be missed (as your operating system doesn't recognize the initial click as coming from a known device). There is a simple fix for this: when you connect your stimulus PC/laptop to the mouse, ALWAYS test that it works by clicking and moving the mouse - this should be detected by your computer as a regular mouse. Do this before starting to scan, and you should have no issues with missed triggers. The problem seems to arise more for certain operating systems (especially MacOS) but it is good practice to always check that the trigger works before starting scanning. It is also good practice to include a visual signal in your stimulus confirming that the trigger has been received if your stimulus doesn't start right away (e.g., if your experiment begins with a blank screen or uses auditory rather than visual stimuli).
+==== Visual presentation ====
+**At CUBIC, we use a back-projection system, using a multimedia projector and a perspex screen viewed by a mirror mounted on the headcoil.**
 VGA port required for connection. (Should work with a HDMI cable??)
-Projector: Sanyo PLC-XP-100L.
+==== Projector: Sanyo PLC-XP-100L ====
+**Recommended resolution:** XXX
-  * Screen size : W 53cm; H 43cm.
+**Refresh rate:** XXX
-  * Distance to screen from the mirror: ~ 72cm.
+**Latency:** XXX
-  * Distance to the mirror from eyes: ~ 10 cm.
+**Screen size:** W 53cm; H 43cm
-Luminance can be adjusted using a polarised filter that slides over the wave guide (the metal tube through the wall). The filter can be rotated to reduce luminance as desired. Please ask Ari for details.
+**Distance to screen from the mirror:** ~ 72cm
-==== How to sync stimuli with scanner acquisition ====
+**Distance to the mirror from eyes:** ~ 10 cm
+Luminance can be adjusted using a polarised filter that slides over the wave guide (the metal tube through the wall). The filter can be rotated to reduce luminance as desired. Please ask Ari for details.
-The scanner sends out a pulse at the onset of every EPI volume acquisition. This pulse is converted to a simulated mouse click through the special mouse connected to the Siemens PC (ask Ari for help identifying it). To use this as a trigger for your stimulus, simply include code to detect a mouse click in your stimulus code. **Please note:** The mouse may not be detected by your stimulus PC until it sends a signal - in some cases this can cause the first trigger from the scanner to be missed (as your operating system doesn't recognize the initial click as coming from a known device). There is a simple fix for this: when you connect your stimulus PC/laptop to the mouse, ALWAYS test that it works by clicking and moving the mouse - this should be detected by your computer as a regular mouse. Do this before starting to scan, and you should have no issues with missed triggers. The problem seems to arise more for certain operating systems (especially MacOS) but it is good practice to always check that the trigger works before starting scanning. It is also good practice to include a visual signal in your stimulus confirming that the trigger has been received if your stimulus doesn't start right away (e.g., if your experiment begins with a blank screen or uses auditory rather than visual stimuli).