Feindel Brain & Mind Series: Ravi Menon

Stop Acquiring Steady-State Event-Related fMRI!

Abstract: Functional MRI (fMRI) studies typically discard the initial volumes acquired during the approach of the magnetization to its steady-state value and acquire data in a continuous manner in this steady-state condition. One can leverage the higher temporal signal-to-noise ratio (tSNR) of the initial volumes to increase the sensitivity of event-related fMRI experiments. To do this, we have introduced Acquisition Free Periods (AFPs) that allow for the full recovery of the magnetization, followed by an acquisition block (AB) of fMRI volumes. An appropriately located/placed stimulus in the AFP produces a Blood Oxygenation-Level-Dependent (BOLD) response that peaks during the initial high tSNR phase of the AB. We can demonstrate up to a ~50% reduction in the number of trials needed to achieve a given statistical threshold relative to conventional event-related fMRI using humans and marmosets. The silent AFP can be exploited for the presentation of auditory stimuli or uncontaminated electrophysiological recording, and its variable duration allows aperiodic acquisition or gating to EEG, cardiac, respiration or motion signals.

Bio: Ravi Menon is Professor of Medical Biophysics and Medical Imaging at Western University and Scientific Director of Western’s Centre for Functional and Metabolic Mapping (CFMM), Canada’s National ultra-high field MRI facility, which houses 3T and 7T human MRI scanners and 9.4T and 15.2T preclinical MRI systems. He is a Fellow of the Royal Society of Canada, Canadian Academy of Health Sciences and a Senior Fellow of the ISMRM. He sits on many advisory boards, including the Brain Canada Foundation and the Michael J. Fox Foundation for Parkinson’s Research. He has received over $170M in research grants, including a $66M CFREF which he Co-Directs, as well as a recent $24M New Frontiers in Research-Transformation award in neurodegeneration. His research involves the development of new structural and functional MRI methods to improve our understanding of the inception and progression of many brain disorders as well as the functioning of the healthy brain through the lifespan.

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