Conceptual and methodological advances in laminar fMRI – David Norris, Donders Institute for Brain, Cognition and Behaviour, Radboud University

March 9, 2020 @ 12:30 pm – 1:30 pm
Lecture Theatre
MRC Cognition and Brain Sciences Unit, 15 Chaucer Road
Johan Carlin

This talk will examine recent progress in laminar fMRI made by our group and others. We will categorise laminar experiments in terms of a framework that distinguishes three main types of response: (I) the response of a cortical region to sensory afferences; (II) the response of a functional sub- unit such as a layer; (III) the response of a functional sub- unit associated with its ongoing state, or (feedback) interactions with another region, that can generally only be revealed with the help of a contemporaneously recorded signal. Type III responses explain how afferent sensory activity is modulated by internal neuronal states, and may offer the most information to neuroscience, but are also the most challenging to measure.

Currently, the two most popular acquisition techniques for laminar fMRI are gradient-echo BOLD and CBV as measured with VASO. Spin-echo BOLD is also a viable alternative. These three methods make different trade-offs in terms of sensitivity, spatial specificity, and volume coverage. I hypothesise that the specificity of these techniques depends on the type of response being measured, and in particular, that for gradient-echo BOLD it is considerably improved when measuring Type III responses. I will support this claim on the basis of recently published and ongoing work from our group.