Virtual Layer-fMRI Dinner #2
Creators: name: Vicioli, Luca
name: Laurentius (Renzo) Huber
name: Seong-Gi Kim
name: Ugurbil, Kamil
name: Melloni, Lucia
Publisher: name: Zenodo
Year: 2020
Subjects: layer fmri

description: Authors are listed on the order of their presentations. <strong>This is the second virtual layer event organized and moderated by Luca Vizioli and Renzo Huber.</strong> In event, it is discussed how the research field can bridge the gap between layer-dependent activity measures that are obtained with fMRI and electrophysiology, respectively. <strong>Kamil Ugurbil</strong> presented the perspective of high resolution for human neuroscience, <strong>Lucia Melloni</strong> presented the perspective of depth-dependent electrophysiological recordings in humans, and <strong>Seong-Gi Kim</strong> talked about the combination of both worlds, layer-fMRI and layer-dependent electrophysiological recordings. Link to video lectures including the introduction from Luca Vizioli and Renzo Huber and the discussion among all attendees: https://www.youtube.com/playlist?list=PLuA0pYRPZ4uDHhVASiAksMPIjMolzXyyk For more information about the event see: https://layerfmri.com/virtualevent2/ <strong>Seong-Gi Kim: Laminar-resolution fMRI in animal models: Signal sources and Implications for human fMRI</strong> Mapping laminar activity is of great interest in human fMRI community due to increased availability of ultrahigh field MRI and a necessity to move toward to systems-level circuit mapping. Recently, many laminar fMRI papers in humans have been published at high profile journals. However, many unsettled questions arise such as whether the fMRI signals are closely related to neural activities at a level of layers, whether the spatial hemodynamic response is close to the neural spread, etc. My lab has been working on understanding underlying vascular sources of laminar fMRI with BOLD, CBF, and CBV contrasts in the cat visual cortex (Zhao et al., Neuroimage, 2006; Jin &amp; Kim, Neuroimage, 2008; Kim &amp; Kim, JCBFM, 2011), and underpinning neural sources in rat olfactory (Poplawsky et al., J of Neurosci, 2015) and mouse somatosensory models. I will present neural sources of laminar fMRI, and discuss outstanding issues and implications for laminar-resolution fMRI in humans. <strong>Kamil Ugurbil: High Resolution Neuroimaging: Accomplishments and Prospects.</strong> Prof. Ugurbil's talk is intended to be broad. The outline of this talk starts with an early view of the history on challenges and problems of columnar imaging and CMRR's solutions to some of them. After the historical overview, Prof. Ugurbil talks about the 'future' of high resolution imaging starting from 2014. The talk is concluded with some recent results of high-resolution fMRI at CMRR. <strong>Lucia Melloni: Laminar electrophysiology: promises and challenges</strong> Lucia starts her presentation by emphasizing that laminar fMRI opens the door to investigate the stream of neural communication across brain areas and thus, allows to address questions about phenomena of human cognition, including conscientiousness and language. Since the laminar architecture of the human brain differs from non-human brains, Lucia stressed the importance of validating the signal origin of laminar fMRI not only in animal models but also in humans. Lucia shows examples of how this can be done by means of depth-dependent electrophysiological recordings of epilepsy patients. One of the key functions of individual cortical layers can be understood in the predictive coding framework by means of prediction error calculation and error model updating. Lucia tested this predictive coding framework with an auditory mismatch-negativity task. She could confirm the prediction error activity (current source density) in superficial layers across patients, as expected in the predictive coding framework. In the final part of the presentation, Lucia discussed that there are layer-dependent differences of the spiking activity (MUA) and high gamma (aka broadband gamma) activity. While both measures are similar for early responses in deeper layers, they can differ in superficial and prolonged activity. The high gamma signal might reflect dendritic processes and they are a good proxy for laminar fMRI signal.