Active Targets

Cursor-tracking target. This specially designated target in the active target list will "follow" the mouse cursor whenever fixation checking is enabled and the cursor is inside the Eye-Target Position panel. To initiate tracking, add the desired target to the active list on the Active Targets dialog page, turn it on, and set its Usage designation to TRACK. Toggle fixation on. Then, as you move the cursor across the Eye-Target Position panel, the chosen target should roughly follow the cursor. The target's current coordinates are updated on the Active Targets dialog as the cursor moves, and if the TRACK symbol is enabled on the position panel, a cyan square will show the target's current position. The target's position is updated every ~20 ms at best. The TRACK target can be toggled on or off by pressing the F3 key; this is useful when you want to turn the target on/off at a particular location in the visual field. Without the shortcut key you have to use the mouse, and the TRACK target will follow the mouse as it leaves or enters the Eye-Target Position panel -- NOT what you want! Additional keyboard accelerators let you increment/decrement the pattern speed and direction of the TRACK target only:

• • F4 increments pattern speed by 5 deg/s, up to a maximum of 150 deg/s.

  • Shift+F4 decrements pattern speed by 5 deg/s, down to a minimum of -150 deg/sec.

  • F5 increments the direction of pattern motion by 15 deg; the resulting angle is always "wrapped" into the unit circle interval [0 .. 360 deg).

  • Shift+F5 decrements the direction of pattern motion by 15 deg.

The cursor tracking feature was introduced to provide a means of roughly characterizing the response of an acquired unit as quickly as possible by manually "waving" an appropriate target across the visual field at different speeds and in different directions while the animal fixates on a stationary point. Typically the user will resize the Eye-Target Position panel as large as possible for finer control of the target's trajectory. Any target that can appear in the active list may be designated as the cursor tracking target, but choose with care. It's always a good idea to try it out before conducting the actual experiment.

IMPORTANT: The state of the active target list is updated only when fixation checking is enabled. For example, if fixation is off and you turn on one of the targets in the active list, it will not physically appear until you enable fixation checking via the Fixation ON/OFF button on the Protocol tab.

The active target list is represented by a grid control on the Active Targets tab. The grid has seven columns:

• • TARGET NAME : To change the identity of a particular target in the active list, simply double-click on the cell displaying its name. An in-place tree control appears on top of the grid, displaying the contents of the Targets branch in the experiment document tree. The current target is initially selected. Browse through the tree control and double-click on the name of the target you want.

  • ON/off : The cells in this column display the current on/off state of the active targets when fixation checking is enabled. To toggle the state of any target, right-click on the corresponding cell. The target should turn on or off immediately if fixation checking is on.

  • USAGE : The cells in this column are used to designate how an active target is used. To edit, double-click on the cell to invoke an in-place combo box with a dropdown list of choices NONE, FIX1, FIX2, BOTH, or TRACK. Alternatively, right-click on the cell to change the usage designation without using the combo box. As discussed above, an active target designated as TRACK will be used as the cursor tracking target; only one cursor-tracking target is supported. Furthermore, any one target can be designated FIX1, a second target can be designated FIX2, or one target in the list can be designated BOTH. The latter two designations have no real utility; they will likely be removed in a future version.

  • Xo, Yo : The cells in these columns display the coordinates of the target's current location in visual degrees subtended at the eye. Coordinate values are limited to floating-point values in [-80 .. 80] deg, with up to 2 digits after the decimal point. To change a coordinate, double-click on the cell to invoke an in-place edit control. Edit the numeric value and hit the Enter key or click outside the edit window to save the new value. Alternatively, right-click on the cell to increment the coordinate by 5 deg, or Shift-right-click to decrement the value by 5 deg. If fixation checking is on, the target's position is immediately updated.

  • V, Dir : The cells in these columns display the target's pattern velocity vector in polar coordinates: V is the radial speed in deg/sec, while Dir gives the direction of motion in deg CCW from the positive x-axis. They are applicable only to targets that possess a distinct pattern that can move independently of the target's window (such as random-dot patches or sinusoidal gratings). Radial speed is limited to floating-point values in [-150 .. 150] deg/sec, with up to 2 digits after the decimal point; the direction angle is restricted to the range [0 .. 360) deg. Either parameter can be edited in the same way as the Xo and Yo parameters. Radial speed is incremented in units of 5 deg/sec, while the direction angle is incremented in units of 15deg.

Three pushbuttons below the grid control change the composition of the active target list. The buttons will be disabled whenever fixation checking is enabled, data recording is on, or a stimulus run is in progress; for technical reasons, Maestro does not permit changes to the active list's composition in these situations. To add a target, press the Add button. The same in-place tree control used to change the identity of an active target will appear; double-click on the name of the target you wish to add. If the list already has 5 targets, the Add button has no effect. Press the Remove All button to clear the active target list, or Delete to remove a particular target (the Delete command is enabled only when the grid's "focus cell" is one of those displaying a target name).