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DCM demo André Bastos and Martin Dietz Wellcome Trust Centre for Neuroimaging.

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Presentation on theme: "DCM demo André Bastos and Martin Dietz Wellcome Trust Centre for Neuroimaging."— Presentation transcript:

1 DCM demo André Bastos and Martin Dietz Wellcome Trust Centre for Neuroimaging

2 pseudo-random auditory sequence 80% standard tones – 500 Hz 20% deviant tones – 550 Hz time standardsdeviants Mismatch negativity (MMN) paradigm and hypothesis time (ms) Paradigm: amplitude (μV) Deviant ERP Standard ERP Hypothesis: MMN is caused by recurrent dynamics enabled by backward connections Garrido et al., Neuroimage 2007

3 Mismatch Negativity scalp topography of ERPs time (ms) sensors standard deviant Deviant ERP Standard ERP time (ms) amplitude (μV) Hypothesis: MMN is caused by recurrent dynamics enabled by backward connections

4 The generative model Source dynamics f states x parameters θ Input u Evoked response data y Observation model g David et al., Neuroimage 2006; Kiebel et al., Neuroimage 2006

5 DCM specification A1 STG input STG IFG several plausible models… modulation of effective connectivity Forward - F Backward - B Both - FB Garrido et al., Neuroimage 2007 Opitz et al., 2002 lSTG rSTG rIFG Deviant response Standard response time (ms) amplitude (μV) What set of areas and interconnections caused the MMN?

6 A1 STG Forward Backward Lateral STG input A1 STG Forward Backward Lateral input A1 STG Forward Backward Lateral input Forward-FBackward-B Forward and Backward-FB STG IFG DCM specification of different models modulation of effective connectivity Garrido et al., Neuroimage 2007

7 Analysis steps 0. Have a HYPOTHESIS! 1.Preprocessing and SVD decomposition 2.Model specification: specify cortical areas and inter- areal connections for various competing models that you think might explain your data 3.Model inversion: find the parameters that minimize differences between observed measurements and model predictions for each of the competing models 4.Bayesian model comparison: make a statistical inferences about which model best describes the data


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