The Fixation Precedence Effect Task Type (Task Type 10)

In the fixation precedence effect task type, the animal is presented with an auditory stimulus and a visual stimulus. Each stimulus has its own starting time, and comes on independently of the other. Each has its own specific duration time, also. The visual stimulus can be disabled by setting led1sel to 0, but you must still specify a starting time (led1strt) and duration time (led1dur) for it, because the program uses these times to help determine when to give the reward.

The auditory stimulus has a starting time of spk2strt and a duration time of spk2dur. As with the Precedence Effect Task Type), the auditory stimulus consists of a specific sound waveform which is played out first from one speaker (spkasel) and then, after a short delay (spkbdel), from another speaker (spkbsel).

Unlike most of the other task types, the animal is not expected to look at either the visual or auditory stimulus for task type 10. The animal is rewarded every time it gets a trial of task type 10, provided the random reward value is set to 1. The time of the reward will be as soon as both the led1dur and spk2dur(+spkbdel) times are finished.

All during this process, the COM program is collecting position data from the cat's eye (and, optionally, ear and head) and also neuronal spike data, as a function of time. After the animal either receives the reward or fails to spot a stimulus properly, the program will continue to collect data for the time period spontim (the spontaneous recording time). At the end of this time period, the trial, or task, is marked as finished, and the program then pauses for a prescribed duration known as the inter-sequence delay. (See the parameters isdrew and isdnorew.) After this, a new trial is begun. The trial process is illustrated in Figure 1a.

Figure 1a. -- Fixation Precedence Effect Task Type

Explanation of terms for fixation precedence effect tasks:

visual stimulus Led1. See led1sel parameter.
auditory stimulus Speakera and speakerb. See spkasel and spkbsel parameters.
DSS dur Duration of auditory stimulus (same for speakera and speakerb). It depends on the duration of the stimulus waveform, as stored in the DSS. It can be less than stim2dur, but not greater than it. See also stimtyp parameter.
SY Starting point of trial.
L1 Time that led1 turns on. See led1strt parameter.
S2 Time that speakera turns on. See spk2strt parameter.
R Time that animal receives reward.
E End of trial.

In order to execute fixation precedence effect trials in the COM program, the user must set up the following files:

Note that while a given trial is being executed, the user can type one of several available commands. The program will complete the current trial (so as not to disturb the timing of the trial), and will then process the command that has been typed.

Com Program Documentation -- General
Task Types
Precedence Effect Task Type
Glossary of Parameters -- definitions of all parameters used

If you have questions or comments about this documentation, please send email to jane@neurophys.wisc.edu
This page last modified on : Dec 5, 2000