Knowledge Base

Using the Pulser (Continued)

A Time condition is placed to allow the instructions in the external command to be processed, before the next external command (that is, the one defining the pulse sequence; see below) is received by the Pulser. Because the two external commands act on the same program cmd.exe, if this Time condition is absent the second command may not be executed by the Pulser which is still busy with the first command.

Important: If you use multiple Pulsers, there may be more time needed to initialize the ports. If the Pulser does not respond it could be due to the 2 s waiting time not being enough. Set a longer time, like 5 seconds or the like.

Procedure 2 - Define the Pulse Sequence

The aim of this procedure is to have EthoVision XT send the command that specifies the sequence parameters.

1. Under Actions choose External command.
2. Select the Program to run and the Command line options as follows (remember to enter the number of your port instead of [n]):

   /C echo MTNT,BI,P1D,P1I,P2D,P2I,TNG,GI,OM,NoT,ToDy,ToDu,ToIt,ToNu@ > com[n]

   For example, for a continuous pulse sequence 20 ms on and 20 ms off, and with COM port 3:

   /C echo M1,0,20,20,20,20,1,0,103,1,0,0,0,0@ > com3

   Note 1: The Operation mode 103 (for PulserPlus, or 3 for Pulser) means that the pulse sequence is generated as long as EthoVision XT sends the TTL command to the Pulser.

   Note 2: If you have the Pulser and the older Pulser software (version 2.1) the command above would be: /C echo 1,0,20,20,20,20,1,0,3,1@ > com3.

3. Click OK and insert the resulting box after the Time Condition box created in the previous procedure.

When this procedure is carried out, the Pulser "knows" what sequence to send out to the LED Controller when it is triggered. The last piece is to program one or more actions in the Trial Control procedure that activate the Pulser at the right time. See the next section.

Procedure 3 - Program Activation of the Pulser

In general, activating the Pulser requires four elements:

1. Trigger condition (wait that the condition is met).
2. Action that triggers the pulser.
3. Stop condition (wait that the condition is met).
4. Action that stops the pulser.

In this example, stimulation is set to start one minute after the start of tracking, and last 1 second.

1. Under Conditions choose Time and set it to 1 minute.
2. Under Actions choose Custom Hardware. Choose the Pulser device. This device must be defined in experiment settings and arena settings. Under Action to perform, select Output 1 High.
3. Under Conditions choose Time and set it to 1 second.
4. Under Actions choose Custom Hardware. Choose the Pulser device as in step 2. However, under Action to perform, select Output 1 Low for deactivating the Pulser.
5. Place the four boxes one after the other.

Tip: Add a condition after the last box, otherwise tracking stops immediately after stimulation stops.

If you want these actions to be repeated, insert them in a Subrule. In the settings of this box, under Stop conditions specify Repeat indefinitely (or as long as required).

Note: Consider the following sequence:

/C echo M1,0,500,500,0,0,1,0,103,1,0,0,0,0

This means that the LED is switched on for 0.5 s, then is switched off for the next 0.5 s. If the Time condition between the trigger actions is set to 1 second, at the end of that time the TTL output sent to the Pulser is still high; this triggers another pulse. As a result, the LED switches on two times (On, Off, On, Off), for a total of 2 seconds.

To have just one sequence, set the Time condition to a time slightly less than one second, for example 0.9. If, on the other hand, you want to have a repeated sequence, it is recommended to set 1.1 s.

Procedure 3b - Program Activation Based on Zone Visit

In this example stimulation is given every time the subject visits a zone named A. The Trial Control procedure is as follows:

1. Trigger condition: Is the subject in zone A?
2. Action that triggers the pulser.
3. Stop condition: Is the subject not in the zone?
4. Action that stops the pulser.

The sequence must be placed in a Subrule, and the Subrule reference is set to Repeat indefinitely, so the Pulser is triggered again at the next zone visit. Set the Action boxes based on the Pulser, not the LED controller.

For More Information

For more information on Subrules, see the EthoVision XT 18 - Trial and Hardware Control - Reference Manual. To open this manual, choose Apps > Noldus > EthoVision XT 18 Other Documentation. For more information on the Pulser, see the Prizmatix Pulser/PulserPlus User Manual.

Program the Prizmatix Pulser/PulserPlus with the Prizmatix Software

It is also possible to define a LED activation sequence with the software that comes with the Pulser/PulserPlus. EthoVision triggers the Pulser with a TTL signal, as shown above. The advantage is that the Prizmatix graphical interface makes the definition simple. However, you cannot change the sequence definition during a trial.

A few things to remember:

• Keep the Pulser software open during your trials. If you have multiple Pulsers, open one instance of Pulser software for each Pulser.
• Make sure that the pulse sequence is defined in the Pulser software.
• Check that the Pulser software indicates that a COM port is selected (COM3, COM4, etc.) and shows the message Prizmatix Pulser is connected. Do this for each instance of Pulser software.
• On the Pulser software, set the Operation Mode to (3) Execute pulse sequence after trigger HIGH, then stop when LOW.
• Before starting the trial, click the Start sequence button. If you work with multiple Pulsers, do so in each instance of the Pulser software. The Pulser software will then wait for the trigger signal from EthoVision XT.

For connection schemes and further details, see the chapter The DanioVision Optogenetics Add-on in the DanioVision DVOC-0041 - EthoVision XT 18 - Reference Manual.

Source: EthoVision XT 18 - Application Manual, Noldus Information Technology