Dynamic causal modeling: Difference between revisions

Revision as of 10:18, 18 June 2018

Revision as of 10:26, 18 June 2018

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=== Experimental design ===

In functional neuroimaging, experiments are typically task-based or [[Resting state fMRI|resting state]]. In task-based designs, brain responses are evoked by known deterministic inputs (experimentally controlled stimuli) that embody designed changes in sensory stimulation or cognitive set. These experimental or exogenous variables can change hiddenneural statesactivity in one of two ways. First, they can elicit responses through direct influences on specific networkbrain nodesregions. This would be appropriateinclude, for example, in modelling sensory evoked responses in the early visual cortex. The second class of inputs exerts their effects vicariously, through a modulation of the coupling among nodes, for example, the influence of attention on the processing of sensory information. TypicThese two types of input - driving and modulatory - are encoded separately in DCM. A 2x2 [[Factorial experiment|factorial experimental design]] is often used - with one factor serving as the driving input and one as a modulatory input.

By contrast, resting state experiments have no experimental manipulations within the period of recording neuroimaging data. Instead, the interest is in the endogenous fluctations in brain connectivity within a scan, or in the differences in connectivity between scans or subjects. DCM has been extended to enable modelling of endogenous fluctuations in absence of experimental input.

=== Preprocessing ===