Triggering the EEG Device

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vinoth kumar

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Jun 29, 2011, 3:16:25 PM6/29/11
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Dear members,
I'm doing a project based upon 'Synchronization of
EEG signal with the Eye Tracker visual stimulus signal' .In that
Project i need to trigger the EEG recorder during the time of
displaying visual stimuli for the participant on the screen.so my
question whether can i able to implement this functionality in ASF
toolbox. if so can you ,gallant members can help me in this program.


Thanks in advance,
Vinoth

Jens Schwarzbach

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Jun 29, 2011, 3:28:53 PM6/29/11
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Dear Vinoth,

I am currently running an experiment in which I issue a trigger on the
parallel port that gets recorded in one channel of a 4-channel audio
card. To my understanding your request would need exactly the same
functionality.

Here is how I do this:

Before calling ASF I make the following settings to the Cfg-structure
Cfg.digitalOutputDevice = 'PARALLEL';
Cfg.issueTriggers = 1;
Cfg.validTriggerValues = 255;


In my ShowTrial function (a plugin derived from the template
ASF_ShowTrialSample.m)

I put the following two lines wherever appropriate (for example right
after the first page flip)
putvalue(Cfg.hardware.DigitalOutput.mydio.TriggerPort, 255)
putvalue(Cfg.hardware.DigitalOutput.mydio.TriggerPort, 0)

I hope this is useful. If this is not detailed enough, I am happy to
provide some more indepth help.

Best,
Jens

Vinoth

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Jun 29, 2011, 3:40:22 PM6/29/11
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Dear Jens
            Glad i got your  help right at this moment .your help at this time is much appreciated and more important to me. i will try it out your suggestion in my program to trigger the EEG device . i will seek your help if i have any clarifications in this project.I thank you for offering your help to me.

Regards,
Vinoth
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V.Vinothkumar,
      Mobile- 07586586958.

vinoth kumar

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Jul 1, 2011, 8:19:11 AM7/1/11
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Dear Dr.Jens,
As you said that we can send trigger pulses to the one
of EEG channel so that it can plot the trigger pulses along with the
EEG channel signal.Here i need your guidance that i need to know about
the hardware required for to transmit the trigger pulse(Digital ) from
the display PC(Eye link) to the EEG recorder (analog channel).Now
actually , the EEG recorder and the Eye link Host PC is connected
under a common DAQ card where the signals are acquired thro'
LabView.Please can you suggest me your idea on selecting the hardware
required to connect the EEG recorder (Biosemi -Active 2 Mark 1 System)
and the display PC (Eye-link 1000 system from SR research lab).

Regards,
Vinoth

On Jun 29, 8:40 pm, Vinoth <velman...@gmail.com> wrote:
> Dear Jens
>             Glad i got your  help right at this moment .your help at this
> time is much appreciated and more important to me. i will try it out your
> suggestion in my program to trigger the EEG device . i will seek your help
> if i have any clarifications in this project.I thank you for offering your
> help to me.
>
> Regards,
> Vinoth
>
> On Wed, Jun 29, 2011 at 8:28 PM, Jens Schwarzbach
> <jvschwarzb...@gmail.com>wrote:

Jens Schwarzbach

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Jul 6, 2011, 6:16:40 AM7/6/11
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Dear Kumar,

let me check if I get you right:
1. you are using an EyeLink 1000

2. your Display PC is running ASF/PTB

3. your EyeLink Host PC is connected to an EEG system by means of a
DAQ card (which is physically in the host PC)

4. You want to send triggers from the display PC to the EEG system

If anything of the above is different from what I wrote, please
correct. I actually don't understand why you are connecting the host
PC with the EEG system and which role LabView is playing. Please have
a look at the following suggestion:

To record eye movements and EEG I would choose the following setup

Eyelink host PC connected via ethernet to Display PC
Display PC connected via parallel port to the digital input of the EEG
system
Display PC runs ASF/PTB

Display PC sends messages to host PC (already implemented in ASF)
Display PC sends trigger signals via parallel port to EEG system
(which either has a parallel port, too, or other digital inputs e.g.
via BNC cables). The commands that send the digital signals from the
display PC to the EEG system are those described below (requires data
acquisition toolbox for Matlab to be installed)
putvalue(Cfg.hardware.DigitalOutput.mydio.TriggerPort, 255)
putvalue(Cfg.hardware.DigitalOutput.mydio.TriggerPort, 0)

If you do not want to use the parallel port (support seems to be
shortlisted for being discontinued in Matlab's data acquisition
toolbox), you can use a DIO card (I am using National Instruments
cards, which are supported by Matlab's data acquisition toolbox and by
ASF).

Best,
Jens
> >       Mobile- 07586586958.- Hide quoted text -
>
> - Show quoted text -

Vinoth

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Jul 6, 2011, 2:54:29 PM7/6/11
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Dear Jens,
       yes,you are absolutely right about my approach.. I am so sorry i made a mistake in establishing the connection link between the PC's and EEG recorder.Actually i had connected the display PC with the EEG recorder system in the DAQ via parallel port but i made a mistake while mailing you  .now i want to transmit the trigger pulses to the external channel input (ex3) of EEG recorder itself since EX1 and EX2 are the input connections for the reference electrodes.That's what i'm trying to point here and requesting for your suggestion here.I think i figured out a way to do this now.. Thanks to you to kindle that idea in me of your clear description about this prob.I will contact you if i face any problem.. I'm so grateful for your great help to me.Thank you very much

Regards,
Vinoth
--
V.Vinothkumar,
      Mobile- 07586586958.

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