SPM5 CBU MEG (Neuromag) Demo
The previous single-subject demo (which included GUI instructions and a batch file) is here: SpmDemoOld. However, many improvements have since been made, so we now demonstrate analysis of a group of 8 subjects with concurrent EEG data.
Introduction
This demo is designed to illustrate some key unique advantages of SPM:
- Multiple Sparse Priors (MSP): A new distributed (L2-norm-like) approach to the MEG/EEG inverse problem, in which several hundred patches of cortex are treated as spatial priors within a Parametric Empirical Bayesian (hierarchical linear Gaussian model) framework (Friston et al, 2008).
- Fusion (simultaneous inversion) of MEG and EEG data: This obviates the need for arbitrary weightings between magnetometer and gradiometer data, or between magnetometer/gradiometer and concurrent EEG data (Henson et al, submitted).
Group inversion: the pooling over subjects in order to optimise the mutliple spatial priors (MSP) before inverting any one subject (Litvak & Friston, 2008).
- The use of model-evidence to compare models: because EM-like algorithm maximises the free-energy bound on the model-evidence
- *to be continued....*
Notes on batch script
At the moment, we provide just a linear Matlab batch script - there are no accompanying GUI instructions yet (eg if you prefer pressing lots of buttons). Though the batch script does require some basic knowledge of Matlab (eg, arrays, cell arrays and simple "for..." and "if..." statements), we strongly recommend batching, for example if you have many subjects, want to keep a record of what you have done, or ever want to re-run with a new parameter/modification. In the future, we expect batching will be made easier (and more modular) by using AA http://imaging.mrc-cbu.cam.ac.uk/imaging/AutomaticAnalysisIntroduction