Drs. Michelle Moerel & Federico DeMartino
Assistant Professors of Psychology and Neuroscience,
Maastricht Centre for Systems Biology, Netherlands Dr. Moerel
An Ultra-high Field fMRI Exploration of the Human Auditory Cortex
The layers of the neocortex each have a unique anatomical connectivity and functional role. Their exploration in the human brain, however, has been severely restricted by the limited spatial resolution of non-invasive measurement techniques. We exploited the sensitivity and specificity of ultra-high field fMRI at 7 Tesla to investigate responses to natural sounds at deep, middle and superficial cortical depths of the human auditory cortex. We compared the performance of a T2*w (GE-EPI) to a T2w (3D GRASE) fMRI dataset, and observed that while encoding and decoding analyses profited from the coverage and sensitivity of GE-EPI, the 3D GRASE dataset achieved higher specificity in topographic maps. We next examined sound processing throughout the depth of primary (PAC) and non-primary auditory cortex, and results suggest that a relevant transformation in sound processing takes place between middle and superficial PAC possibly serving as a first computational step towards sound abstraction. Dr. De Martino
Imaging the Human Auditory Pathway at High Fields: Computational Models and High-resolution Functional and Anatomical Characteristics
Dr. De Martino will detail a series of high field (7 Tesla and above) MRI experiments oriented to the definition functional and anatomical properties of of the human auditory pathway (sub-cortical and cortical). Functional characteristic will be described on the basis of computational models of sound processing. Pushing the limits of spatial resolution, he will present the most recent data highlighting the presence of a columnar cortical organization, the relevance of layer dependent processing in extracting relevant sound properties, the modulation of cortical layers in dependence with task demands and the ability of high resolution fMRI to reveal a topographic representation of acoustic properties also in the small sub-cortical structures. Together with the functional studies, I will also present investigations of cortical myelination and preliminary results on high-resolution diffusion weighted imaging and resting state fMRI data. These results represent an effort to the in-vivo characterisation of the human auditory pathway at high spatial resolution and an example of the relevance of high field (high-resolution) studies in linking in vivo measurements of brain activity with computational models of sound processing. This lecture is made possible in part by a generous Endowment by the family of Allen. L. Edwards. |