Mixed Effect Modelling of Single Trial Variability in Ultra-High Field fMRI

Neuronal brain activity in response to repeated stimuli can be perceived using functional magnetic resonance imaging (fMRI). In this paper, we develop a statistical model for fMRI data that estimates both the associated haemodynamic response function and the within and between trial variability through maximum likelihood estimation. We discuss our results in the context of other model-driven approaches, extending models already popular in the literature, while removing the need for some of their assumptions. We consider an application to the motor cortex activity caused by a subject pressing a button and observe that the response changes significantly with task and through time.