Targets
A "target" in Maestro is a programmable visual or non-visual stimulus. The investigator controls the target's trajectory and can turn it on or off at prescribed times during an experiment. Visual targets are realized on one of two distinct display platforms: XYScope targets are animated on an analog vector X-Y oscilloscope, while RMVideo targets are displayed on a color CRT monitor driven by a high-performance graphics card under the control of an OpenGL application running on a separate Linux workstation. Often an experiment rig will include both displays, but targets are never animated on both simultaneously. These video targets come in a variety of target types, each with a set of defining parameters. These parameters are displayed and modified on Maestro's Target Editor, one of the five panels in the tabbed window on the right-hand side of the frame window's client area.
In experiments on the vestibulo-ocular reflex (VOR), it is common to rotate the subject while simultaneously presenting a visual stimulus on the X-Y oscilloscope or the RMVideo monitor. Some Maestro rigs include a large rotational turntable -- the predefined Chair target -- for this purpose. The turntable is driven by a velocity servo that is, in turn, controlled by one of the analog outputs from Maestro. Unlike a visual stimulus, the Chair target cannot be turned "on" and "off" during a trial or stimulus run. Also, because the turntable has considerable inertia, you may have to tinker with its trajectory variables to achieve a desired motion (and you certainly cannot change its position "instantaneously"!).
The pages in this section describe all of the video target types in greater detail and explain how to use the Target Editor to edit the defining parameters of an XYScope or RMVideo target object.
Maestro 3: Bye-bye, Optic Bench!
Before the introduction of the XYScope and RMVideo display platforms, Maestro's predecessor presented simple spot targets back-projected on a translucent screen. Two fiber optic light sources were reflected onto the screen via pairs of mirror galvanometers that ultimately controlled the X and Y positions of the spots on the screen. The spots were turned on/off by shutters. In addition, up to two stationary red LED spots could be projected on the screen. These were also shuttered and were generally used as central fixation points. The light sources, galvos and shutters were carefully arranged on an optic bench behind the screen.
While Maestro 1.x and 2.x supported these "optic bench" targets (Fiber1/2, REDLED1/2), they gradually fell out of use as researchers relied more and more on XYScope and, later, RMVideo targets. As of Maestro 3.0, they are no longer supported.
Maestro 4: Bye-bye, XYScope!
The XYScope target platform was a large analog vector oscilloscope driven by a custom "dotter board" that, in turn, was driven by the outputs of a Detroit C6x DSP card controlled by Maestro.
Unfortunately, the analog scopes are no longer manufactured, and the lab no longer has any working scopes. Furthermore, the antiquated DSP card that served as the XYScope controller has a conventional PCI bus, which is no longer supported in current computers.
For these reasons, Maestro 4 does not offer hardware support for the XYScope platform. However, you can still define XYScope targets in a Maestro experiment document. We decided to maintain all XYScope-related code in case we develop an alternative implementation of the display platform in the future.