MR Hardware
Stimulus Presentation
Flat Panel
The 30 inch flat panel display was built by Resonance Technology. It is based on a Samsung LCD panel, similar (maybe identical?) to that used in the Dell Untrasharp U3011 and the HP ZR30w. It has a native resolution of 2560x1600, 7ms temporal response, and 10-bit color rendering. It is driven by a dual-link DVI-to-fiber converter to pass clean digital signals into the scan room. If you do not drive the system with a dual-link capable computer, you can not achieve the native resolution. In that case, we suggest that you use 1280x800 (half-native). Note that you must drive this system with a digital signal (DVI-D or dual-link DVI-D). A simple VGA-to-DVI will not work, as it outputs analog DVI-A signals. We have a video scaler box that will digitize VGA inputs and allow you to drive the display, but we suggest that you avoid doing this and try to configure your stimulus delivery system to use a DVI-d digital output. This display is positioned at the back of the bore (70cm from the top shroud around the bore) with a total viewing distance of 190cm.
Goggles
The Resonance Technology VisuaStimDigital provides a goggle display that provides a large field of view (~40 degrees wide) and the ability to easily present different stimuli to each eye. With the goggles, you can create an immersive 3d environment or present stereoscopic visual stimuli. However, the image quality of the goggle system is not nearly as good as that of the flat panel display. The resolution is lower (800x600), the color rendering is much poorer, the gamma curves are odd, and there are some ghosting artifacts due to the analog signals.
The goggles are a tight fit in the head coils. To get them in, first position the subject with the coil slid back out of the way. Then, position the goggles in the coil and slide the coil and goggles together over the subject's face. Note that for some subjects with large heads, the goggles might not fit comfortably in the 32-channel coil.
Auditory
The auditory system is part of the Resonance Technology VisuaStimDigital. (TO DO: Add more info here.)
Olfactometer
The McClure lab will maintain a 32-channel olfactometer. (More info soon.)
Subject measurement
Response Box
We have a modular response box system (fORP 932) from Current Designs. With ths system, you can swap out various response devices. The output from any of these devices is available from the fORP box via USB. The device emulates a USB keyboard. (Note that we have found more reliable operation with PsychToolbox by using the "USB HID NAR" mode rather than the "USB HID KEY" mode. With KEY mode, some keypresses are missed.) We have confirmed that the fORP 932 USB interface is polled at 1kHz. The device itself has sub-millisecond time resolution (see the fORP FAQ). We estimate that this system provides response time measurements with a precision and reliability of about one millisecond.
The response devices that we currently have are:
- scroll-wheel device
- bimanual button boxes
- trackball device (on back-order; should arrive in a couple of weeks)
- 4-button stick-style response device.
Eye Tracker
The current eye tracking system is the MReyetracking system from Resonance Technology. The eye camera and IR source mounts to a silicone eye piece that can replace the silicone eye piece on the goggles to do eye tracking with the goggles. You can also use this camera and eyepiece as a standalone eye tracker for use with the flat panel display.
The eye camera video is processed by ViewPoint from Arrington Research. This software is running on the Dell computer that sits directly behind the scan operator. To position the eye camera properly, it is helpful to see the video output. To do this, start ViewPoint on the Dell and use the video switch that sits on top of the GE console computer to show the ViewPoint window on the little display that is mounted to the scanner above the subject bed.
Subject monitoring
The scanner has the standard suite of physiological measures: pulse oximetry, respiration belt, and ECG. These can be used for scan triggering. Also, the digital data from these measurements can be saved.
Several labs have asked about a video camera positioned in the bore to monitor the subject's face.
Scan Triggers
Protocol configuration
TO DO: Document UserCVs for setting up triggering.
USB-1208 HID trigger
At the CNI, we have a [USB-1208] HID device from Measurement Computing installed and wired into the scan trigger through pin 14. This device is supported by the PsychToolbox [DAQ Toolbox]. If you have PsychToolbox configured, just plug in the USB cable labeled "Trigger" and you can send a TTL pulse to the scanner by pulsing pin 14. See the VistaSoft [StartScan] function for example Matlab code.
Serial Port Trigger
The CNI also has a USB-to-Serial port device set up to send scan triggers. Just connect the USB cable labeled "Serial Trigger" to your computer. You might need to install a driver the first time you connect it. Download the Arduino Uno driver and then follow these instructions. The device is expecting communication at 57600 bps. The scanner is triggered by sending this string (without the quotes): "[t]".
Subject Positioning
There are many MR-safe pads available for subject positioning. (Add positioning advice?)
Also, there is a Mag Design and Engineering bite-bar holder on the 8-channel coil (built by Ben Krasnow). We will also get one built for the 32-channel coil if there is a need (i.e., someone asks). We have a 200deg water source in the control room (the Cuisinart coffee machine) and are planning to get a little microwave for heating things like bite bars and EEG electrolyte.
Some labs have expressed interest in a vacuum pillow system for subject positioning. From: Ashley Shurick (Gross lab) is familiar with the SecureVacTM Immobilization System from Bionix Radiation Therapy. The system at NYU uses a customized pillow measuring 50 x 70 cm with 12.5L of fill. However, the size should depend on the head coil used, as pillows come larger or smaller, with more or less fill. They also have a vacuum pump system to remove air from the pillow, helping prevent movement. We are currently looking int this.