yes, that is what you want. The only other way that comes to mind is to 
model each event type as two event types one delayed relative to the 
other. Then model the responseto each as a gamma. If the delay is right, 
then the first gamma should model the main positive response and the 
second gamma will model the negative response. both will be independent 
from the other.

doug

On 04/10/2013 05:00 PM, sha...@nmr.mgh.harvard.edu wrote:
> I think I figured it out but I want to double check. I am generating
> group-average map for my subjects using isxconcat-sess command which
> generates ces maps for each time frame. I think these maps are what I
> wanted. Right?
>     If you still have other solutions that you think may generate more
> reliable results, I am eager to know. For instance, is there anyway to
> fit a model as we do for spmhrf or fslhrf, but just for the negative
> peak?
>
> Regards
>
>> That's the problem Doug. I have already generated the FIR model but how
>> can
>> I show the sig MAP for one "particulat time point".  What are the other
>> ways?
>>
>>
>> On Wed, Apr 10, 2013 at 4:05 PM, Douglas N Greve
>> <gr...@nmr.mgh.harvard.edu>wrote:
>>
>>> Hi Shahin, there are several ways that you could do it. The one that
>>> immediately comes to mind is to use an FIR and then test for a
>>> difference
>>> at a particular post stimulus time point.
>>> doug
>>>
>>>
>>>
>>>
>>> On 04/10/2013 03:54 PM, SHAHIN NASR wrote:
>>>
>>>> Hi,
>>>>       I want to generate a map to show the significant difference
>>>> between
>>>> HRF undershoot  (negative peak of activity) between two conditions
>>>> independent from the positive peak. Is there anyway, to generate this
>>>> map?
>>>>
>>>> P.S.: Please note that I need a map and not a time course graph.
>>>>
>>>>
>>>> --
>>>> Shahin Nasr
>>>>
>>>> PhD in Cognitive Neuroscience
>>>> Martinos Imaging Center, MGH
>>>> Harvard Medical School
>>>>
>>> --
>>> Douglas N. Greve, Ph.D.
>>> MGH-NMR Center
>>> gr...@nmr.mgh.harvard.edu
>>> Phone Number: 617-724-2358
>>> Fax: 617-726-7422
>>>
>>> Bugs:
>>> surfer.nmr.mgh.harvard.edu/**fswiki/BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting>
>>> FileDrop:
>>> www.nmr.mgh.harvard.edu/**facility/filedrop/index.html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html>
>>> Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/**
>>> greve/ <ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/>
>>>
>>>
>>>
>>
>> --
>> Shahin Nasr
>>
>> PhD in Cognitive Neuroscience
>> Martinos Imaging Center, MGH
>> Harvard Medical School
>>
>>
>>
>> --
>> Shahin Nasr
>>
>> PhD in Cognitive Neuroscience
>> Martinos Imaging Center, MGH
>> Harvard Medical School
>> _______________________________________________
>> Freesurfer mailing list
>> Freesurfer@nmr.mgh.harvard.edu
>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
>

-- 
Douglas N. Greve, Ph.D.
MGH-NMR Center
gr...@nmr.mgh.harvard.edu
Phone Number: 617-724-2358
Fax: 617-726-7422

Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting
FileDrop: www.nmr.mgh.harvard.edu/facility/filedrop/index.html
Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/

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