A mechanistic model of mismatch negativity in the ageing brain

Objective: We investigated the neurophysiological mechanisms underpinning the generation of the mismatch negativity (MMN) in the ageing brain. Methods: We used dynamic causal modelling (DCM) to study connectivity models for healthy young and old subjects. MMN was elicited with an auditory odd-ball paradigm in two groups of healthy subjects with mean age 74 (n= 30) and 26 (n= 26). DCM was implemented using up to five cortical nodes. We tested models with different hierarchical complexities. Results: We showed that the network generating MMN consisted of 5 nodes that could modulate all intra- and inter-nodal connections. The inversion of this model showed that old subjects had increased input from rSTG to the rIFG (