Operation of peripheral devices

• I want to play auditory stimuli through the RT intercom headphones. How I should connect my PC to the intercom?
• When should I use waveguides (circular apertures with installed cylinders in the penetration panel) for passing cables of my experimental setup into the scanner room and when the cables should go through the RF filters installed on the panel?
• I would like to use a TTL trigger from the scanner to start my paradigm. Which output should I use?

• I want to play auditory stimuli through the RT intercom headphones. How I should connect my PC to the intercom?

The new RT headphones offer stereo sound quality and dynamic range sufficient for decent auditory brain imaging experiments.
-The audio output of a stimulus PC should be connected to the RT Commander unit (AUX connectors in the back) by a stereo 3.5mm Plug to RCA-Type plug cable.
-video inputs (as opposed to audio, which is reserved to the stereo system) should be selected by pressing the Audio Input Selector button in front of the unit as indicated by a green light.
-The master volume control (rightmost handle) and the stereo volume control (middle two handles) on the RT control unit should be adjusted so that the sound is equalized.

• When should I use waveguides (circular apertures with installed cylinders in the penetration panel) for passing cables of my experimental setup into the scanner room and when the cables should go through the RF filters installed on the panel?

Only non-electric cables such as fiber optic cables, tubes delivering solutions (e.g. for taste/smell experiments) or water (e.g. hot water for nociception or anesthesia experiments) can go directly through the waveguides, as the electric cables bring in noise into the scanner room. All electric cables have to be interrupted by RF filters installed on the penetration panel. Currently four 9-pin (for RT intercom, physio-monitor, respiratory cable, and a spare) and one 25 pin DB connector (for oxygen monitor) are installed. Additional filters can be installed on demand.

• I would like to use a TTL trigger from the scanner to start my paradigm. Which output should I use?

There are two kinds of TTL trigger pulses produced by the scanner.
1. The BNC labeled by red tape produces a trigger pulse at the beginning of each block defined by the Paradigm Manager. It is available only if the fMRI option and, hence, BrainWave GUI is enabled. This trigger pulse is not available in research mode selected via fMRI screen. The duration of the pulse (1 msec ) is sufficient for most stimulus presentation programs that use the parallel port to read the trigger pulse (such as Presentation or E-Prime).
2. The BNC labeled by the black tape produces a trigger pulse before acquisition of each slice, regardless of a pulse sequence. It is available in any mode, so can be used with BrainWave disabled. However, the duration of this TTL pulse is only 1 microsec. Therefore before it can be detected by stimulus presentation software on the parallel port its duration has to be extended by means of the white pulse extension box.