% Event related fMRI analyses for SPM'96 - SPM'97 %_______________________________________________________________________ % % NOTE: In addition to providing an event-related fMRI interface for % SPM, this "kit" includes an updated interface for block fMRI % analyses, incorporating various features beyond those in SPM96. These % advances result in slightly different results to SPM96 (although % results files are cross-compatible between the two implementations). % SPM96 with this kit on top should be referred to as SPM97, a tag % which has been used in the literature. % % We recommend you maintain the integrity of your SPM96 installation % and install this kit in a seperate directory to SPM96. Place the % directory containing this kit before SPM96 on your Matlab path when % you wish to use SPM97 event related or the updated block fMRI % interface. % %_______________________________________________________________________ % % Event-related fMRI (efMRI) % % SPM offers the possibility to analyse efMRI studies. The basic concept % is identical to blocked fMRI analyses, using the GLM. The difference is % only the design matrix and the plotting routines. In the current % implementation SPM creates a sparse matrix n x t for n events over time % t. This matrix is created with a temporal resolution of 100 msec. The % events are modelled as delta functions ('ones' in this matrix). This % matrix containing ones modelling an event and zeros elsewhere is then % convolved with the basis function(s) you specify. This is still done at % 100 msec resolution. Since there is only a single observation per scan % and this is likely to cover more than 100 msec, the matrix is % downsampled to match the TR that has been entered. The user's choice is % mainly the set of basis functions to be used: % % * Fourier set : Sines and cosines % * Windowed Fourier set : Sines and cosines windowed with a Hanning window % * Gamma functions : Set of three gamma functions % (early, middle and late) % * Gamma functions % with derivates : As above plus the derivatives % * HRF : Synthetic hemodynamic response function % * HRF + derivative : As above plus the partial derivative with respect % : to time. This can model shifts of the HRF in time. % * HRF + temp. deriv & % dispersion derivative : As above, plus the partial derivative with respect % to the dispersion parameter of the gamma function. % This can model 'sharper' or 'flatter' responses % % SPM will create an additional *.mat file (ER.mat) for this analysis. % Load this file and plot the variable DER to see the basis function(s) % you have used. % % ---------------- % % The plotting routines have been extended to cope with efMRI analyses. % You can plot the estimated HRF time locked to the events. This menu % offers several options: % % 1. Plot the modelled response only % 2. As above but with the SEM % 3. As above but with the SEM for the onset of the response % 4. Plot the modelled response and the data points % % % ---------------- % % Some general guidelines % ----------------------- % % Events can be equally or unequally distributed over time. In the former % case you only have to specify the time between two events. In the % latter case SPM expects a vector of time points when events occured. % SPM expects time in scans [i.e. an event at 10 seconds with a TR of 4s % has to be entered as 2.5 (TRs)]. Differences between events can be % estimated in two ways: Using t-statistic when comparing two events % modelled by a single basis function (eg. HRF alone). Howver,this gets % problematic if you model your events as a linear combination of more % than one basis function (eg. Fourier set). In this case you can use the % F-statistic and the option 'model differences'. If you model your % events as 'HRF alone' you choose the option 'all events' and test for % differences with contrasts. % % ---------------- % % References % ---------- % % Theory and implementation: % Josephs O., Turner R., Friston K. (1997) % Event-related fMRI. % Human Brain Mapping 5:243-248 % % Friston K. J., Fletcher P., Josephs O., Holmes A., % Rugg M. D., Turner R. (1998) % Event-Related fMRI: Characterizing differential responses. % Neuroimage 7:30-40 % % Non-linear extension: % Friston K. J., Josephs O., Rees G., Turner R. (1998) % Nonlinear event-related responses in fMRI. % Magnetic Resonance in Medicine 39:41-52 % % Application: % Buechel C., Morris J., Dolan R. J., Friston K. J. (1998) % Brain systems mediating aversive conditioning: % an event-related fMRI study. % Neuron 20:947-57 % %======================================================================= % % The event-related fMRI kit for SPM'96 - SPM'97 % % The SPM96 event-related fMRI kit for SPM96 consists of: % % spm_efmri.man - this file % % spm_AnCova.m (v1.6) - replacing v1.4 of SPM96 % spm_Volt_W.m (v1.1) - new % spm_fmri_spm_ui.m (v1.35) - replacing v1.17 of SPM96 % spm_graph.m (v1.17.1.1) - replacing v1.3 of SPM96 % spm_graph_ui.m (v1.1) - new % spm_hrf.m (v1.2) - new (included in RFX kit too) % spm_results_ui.m (v1.10.1.1) - replacing v1.7 of SPM96 % spm_spm.m (v1.32) - replacing v1.23 of SPM96 % spm_sptop.m (v1.7) - replacing v1.2 of SPM96 % (included in RFX kit too) % % ---------------- % % spm_AnCova.m : updated core routines for the general linear model % spm_spm.m : % % spm_Volt_W.m : creates gamma-functions % spm_hrf.m : creates the synthetic hemodynamic response % spm_sptop.m : creates toeplitz matrix for temporal smoothing % % spm_fmri_spm_ui.m : The main routine for fMRI. This routine creates % the design matrix and sets up the analysis % % spm_graph.m : % spm_graph_ui.m : extended plotting routines for ER-fMRI % spm_results_ui.m : % %_______________________________________________________________________ % @(#)spm_efmri.man 1.2 Christian Buechel 98/07/31