Dear Haiteng,
> I wonder if UPPT001_up is the sign of trigger? And If I set
> pre-trigger time -1995ms, post-trigger time 995ms, Does that mean that it
> reads the data of trial form 5ms to 2995ms?
This is the kind of questions one cannot answer by looking at the data
alone. This is something you should work out with your MEG
technicians. It's quite likely that UPPT001_up is the right trigger
but not necessarily. It all depends on how your MEG system is set up.
On some systems (i.e. at the FIL) the trigger is down-going. Also the
timing of your video in relation to the trigger is something I have no
way to know, but this is something that people who set up your
stimulus presentation should know. If you have no other way, you can
just set up something like a light sensor in front of your screen and
record the output with the MEG to get the timing. But first just talk
to the people who run your MEG.
Best,
Vladimir
2009/3/18 hiten <[log in to unmask]>:
> Dear Vladimir,
> Thanks for your reply. As you say ,when I set pre-trigger time
> -2000ms, post-trigger time no bigger than 1000ms,such as 995ms ,this warning
> does not prensent. Yestoday, The MEG operator told me that he set the
> pre-trigger time at -2s. My trial sustained a 3s video play. The interval
> between trials is uncertain . Another problem arises.
> Take the first trial as an example,the detail information is in attachment
> convert.jpg
> label type value duration time
> bad onset
> undefined trial 0 3600 -2
> undefined 0.0008333
> undefined UPPT001_up 1 0 0
> undefined 0.0008333
> undefined pic-1 0 0 0
> undefined 0.0008333
> undefined UPPT001_down 1 0
> 0.001667 undefined 0.0008333
> undefined FIL_UPPT001_down 0 0
> 0.001667 undefined 0.0008333
> undefined trial 0 3600 1
> undefined 0.0008333
> I wonder if UPPT001_up is the sign of trigger? And If I set
> pre-trigger time -1995ms, post-trigger time 995ms, Does that mean that it
> reads the data of trial form 5ms to 2995ms?
>
>
> Thanks in advance!
> best
>
>
>
> --
> haiteng jiang
> Research Center for Learning Science,
> Southeast University
> Si Pai Lou 2 # , Nanjing, 210096, P.R.China
> Brain Imaging Lab
> Mobile:+86-13813998827
> Email: [log in to unmask]
>
> 在2009-03-17 15:26:51,"Vladimir Litvak" <[log in to unmask]> 写道:
>>Dear Haiteng,
>>
>>That warning means that one trial too close to either the beginning or
>>the end of the continuous file. Lets say that your last trigger comes
>>2 sec before the end of the recording and you asked for -0.1 to 3 sec
>>trials then this trial will not be extracted as part of the data is
>>missing. Similar thing can happen at the beginning of the file. You
>>should either go ahead and accept the loss of one trial or make your
>>trials short enough so that this trial won't be lost.
>>
>>Best,
>>
>>
>>Vladimir
>>
>>2009/3/17 hiten <[log in to unmask]>:
>>> Dear SPMEers:
>>> I have one problem. Now I am using spm8b to process VSM ctf-275 MEG data
>>> .after convert,when I epoch ,the follwing warning presents:
>>>
>>>
>>> Warning: spm8_DP01YANGPEICHAO.mat: Events 200 not extracted - out of bounds
>>>
>>>> In spm_eeg_epochs at 156
>>>
>>> After convert,the infomation about spm8_DP01YANGPEICHAO.mat is in
>>> attachment convert.jpg
>>>
>>> the epoch step is in attachment epoch.jpg
>>>
>>> I have 200 trials ,each lasts for 3 second. The 200 trials are divided into
>>> five conditons: eat,neural ,sad,happy,cross,each has 40 trials.
>>>
>>> No matter I try Type ;UPPT001-DOWN,Value: 1,2,3,4,5 or the Type ;UPPT001-UP
>>> value: 1,2,3,4,5,the warning is still existence .
>>>
>>> If I go on ,after artefacts,averaging. the follwing produces:
>>>
>>> averaging cross: 39 trials averaging eat:40 trials averaging neural : 40
>>> trials averaging happy: 40 trials
>>>
>>> aveaging cross:40 trials
>>>
>>> Obviousely, the 200th trial has been lost .I don't konw why .Is there any
>>> wrong settings in my procedure?
>>>
>>>
>>>
>>> I hope someone can give me suggestion.Thanks in advance!
>>>
>>>
>>> --
>>> haiteng jiang
>>> Research Center for Learning Science,
>>> Southeast University
>>> Si Pai Lou 2 # , Nanjing, 210096, P.R.China
>>> Brain Imaging Lab
>>> Mobile:+86-13813998827
>>> Email: [log in to unmask]
>>>
>>>
>>> ________________________________
>>> 网易邮箱,中国第一大电子邮件服务商
>
>
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