Measuring effects of latency in brain activity with fMRI

In fMRI analysis, general linear modelling (GLM) is commonly used because of its explanatory power, statistical simplicity and computational efficiency. Such models primarily measure the parametric effects of experimental conditions on amplitude of activation, and neglect other important effects on nature of the hemodynamic response, including its temporal characteristics such as relative latency (delay). In this paper, we present a GLM approach to estimate experimental effects on, not only activation amplitude, but also latency. We validate the statistical properties of our method through simulations, and show that on in vivo fMRI data, latency can characterize aspects of neural recruitment during different cognitive tasks, that amplitude alone cannot.