Hi all,<br><br>I&#39;ve been trying to analyses both an event related and block design experiments and have noticed a couple things that are confusing me and I would appreciate any help anyone could give me.<br><br>1.  In trying do the event-related analysis, I&#39;m am a bit confused by the FIR vs Gamma analysis and the use of the time window and tprestim in the FIR analysis.  I have an experiment with 6 set size conditions and 1 fixation condition.  each trial is 6s long with a TR of 1.5<br>

<br>I have run both of these commands:<br><br> mkanalysis-sess.new -analysis supIPS_loc -TR 1.5 -paradigm supIPS.dat -designtype event-related -funcstem fmc -motioncor -runlistfile supIPSruns.txt -inorm -nskip 2 -nconditions 6 -gammafit 2.25 1.25<br>

<br>mkanalysis-sess.new -analysis supIPS_loc -TR 1.5 -paradigm supIPS.dat -designtype event-related -funcstem fmc -motioncor -runlistfile supIPSruns.txt -inorm -nskip 2 -nconditions 6 -tprestim 2 -timewindow 20<br><br><br>

The FIR gives me a time course window, which makes me think that perhaps that is the one I want to use, but it shows very little activation.  This data has been previously analyzed in Brain Voyager, so I know it&#39;s not a case of the conditions not actually causing activation, but for some reason, the FIR analysis doesn&#39;t show any.  I&#39;m not sure if this is due to a bad time window/tprestim settings, or something else.  However the gamma fit analysis shows a bunch of activity where I expect to see it, but no time course window.  (attached are pngs of the differences for the act_vs_fixation comparison).  <br>

<br><br>2.  In addition, in both the event related (gamma) and a normal block design (different experiment) I get very different results (at least for certain comparisons) depending on whether I use selxavg-sess (with stxgrinder-sess for each contrast) or selxavg3-sess.  The differences are shown in the attached pngs (act_vs_fix-gamma.png (which is the selxavg-sess and stxgrinder-sess analysis and act_vs_fix-gamma-selxavg3).  In the block design, both selxavg3 and selxavg (+stxgrinder) give me very similar activation when comparing two non-null conditions (ie. shape_vs_noise) but very different (and similar to the differences in the attached pictures) activations when comparing against the null (ie shape_vs_fix or noise_vs_fix).  What am I doing wrong here?<br>

<br>Thanks for your help!<br><br>Katie<br>