Dept of Neurophysiology -- Precedence Effect (with Stimulus2 Spotting) Task Type

The Precedence Effect (with Stimulus2 Spotting) Task Type (Task Type 6)

In the precedence effect task type, the animal is presented with a first stimulus, which is purely visual -- there is no auditory portion. The animal is expected to spot or look in the direction of this stimulus for its duration (led1dur). At this point, a second stimulus, which is purely auditory, is presented. It 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). The animal is expected to move its eye to the direction of spkbsel (NOT spkasel), and continue to spot there for the time duration stay2dur. Note that this differs from task type 5, Precedence Effect without Stimulus2 Spotting, where the animal is not required to look at the second stimulus at all.

If the animal succeeds in looking in the required directions for the required durations, it will receive a reward. Otherwise, it fails the task and is not rewarded. Note that it is allowed the time tspotl1 to look at led1, and tspots2p to look at the speakerb.

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. -- Precedence Effect (with Stimulus2 Spotting) Task Type

Explanation of terms for precedence effect tasks:

first stimulus Led1. See led1sel parameter. This stimulus is visual only.
second stimulus Speakera and speakerb. See spkasel and spkbsel parameters. This stimulus is auditory only.
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 and/or speaker1 turns on. See led1strt parameter.
W1 Time that animal spots into window of first stimulus.
L2 Time that speakera turns on. For the precedence effect task type, this always occurs at the end of led1dur.
W2 Time that animal spots into window of second stimulus.
R Time that animal receives reward.
E End of trial.

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

Fixed Parameter File - This file contains the list of parameters that retain the same values for all trials of a given run of the COM program. There are at least 50 parameters in this list, and they must be specified whenever COM is run. Here is an example of such a fixed parameter set.
Precedence Effect Parameter File - This file contains the list of parameters that define a set of precedence effect trials. The user may specify one or more of these files, each containing a different precedence effect parameter set. Here is an example of one such parameter set.
Macro File - This file contains the list of parameter sets to be used for a run of the COM program. It must contain one fixed parameter file, and one or more parameter set files, as described above. Here is an example of one such macro file.

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 without Stimulus2 Spotting
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 : July 22, 1996

first stimulus	Led1. See led1sel parameter. This stimulus is visual only.
second stimulus	Speakera and speakerb. See spkasel and spkbsel parameters. This stimulus is auditory only.
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 and/or speaker1 turns on. See led1strt parameter.
W1	Time that animal spots into window of first stimulus.
L2	Time that speakera turns on. For the precedence effect task type, this always occurs at the end of led1dur.
W2	Time that animal spots into window of second stimulus.
R	Time that animal receives reward.
E	End of trial.