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Dear all, We wish to remind you of the upcoming abstract deadline (15 August, 2012) for this call<http://www.frontiersin.org/Human%20Neuroscience/researchtopics/Resolving_differences_between_/906> for papers in a Research Topic in the Frontiers in Human Neuroscience journal<http://www.frontiersin.org/Human_Neuroscience>, entitled: "Resolving differences between electrophysiology and haemodynamics - What does my metric mean?" The final paper deadline is 31 October, 2012. Please note that contributions will be treated as normal papers in a full peer-review process. We are very pleased that the following distinguished scientists have already confirmed to contribute: Stephen Hall, David Norris, Sri Nagarajan, Fa-Hsuan Lin, Todd Woodward, Suresh Muthukumaraswamy, George Ojemann, and Tom Liu. Best regards, Claire Stevenson, Johanna Zumer, Matt Brookes, Peter Morris, Sue Francis (co-host associate editors) Description: > Since the first demonstration of BOLD fMRI, systems neuroscience has been > revolutionised by our ability to non-invasively map functionality in the > human brain. BOLD has elucidated the structure and function of distributed > networks and allowed assessment of functional connectivity between > spatially separate regions. However, despite its wide utility, the > relationship between BOLD and the underlying electrical activity is still > under debate. A number of studies address neurovascular coupling, and > advances in multi-modal imaging are allowing increasingly complex questions > to be posed, resulting in a wealth of new data. In light of such progress, > here we revisit the question; What drives the BOLD response? > > First, we question the role of neural oscillations and their relationship > with haemodynamics. Investigations of scalp based (E/MEG) and invasive > (ECoG) measures of oscillations describe the co-expression of finite, > discrete frequency bands spanning 0.05 to 500 Hz. Parametric modulation of > frequency specific oscillatory power has been related to cortical > processing and, for low level sensory stimuli, has shown a good spatial > correspondence with BOLD fMRI. On this basis, the powers in several > frequency bands have been proposed as strong candidates for the signal > driving the BOLD response. However, results for task-related amplitude > correlation between neural oscillations and haemodynamics are somewhat > inconsistent, and more variable with the move to more cognitively demanding > tasks studying multiple brain regions. > > Second, we ask whether phase-locked evoked components of neural activity > from E/MEG recordings show significant correlation with BOLD. The results > to date are again variable, with amplitude and latency of evoked components > exhibiting both positive and negative correlation with BOLD depending on > the task. It is noteworthy that many analysis techniques in E/MEG are tuned > to either evoked (e.g. minimum norm) or induced (e.g. beamforming) > responses, meaning that many studies only examine aspects of either evoked > or oscillatory responses to compare to BOLD, leaving the question open as > to which of these more closely correlates. > > Finally, we ask what information can be gained from multi-modal > connectivity measurements? Synchronisation of oscillatory activity between > regions has long been posed as a mechanism for long range interaction. The > recent shift in fMRI towards a brain-wide view of inter-regional > connectivity shows that networks drive correlated BOLD fluctuations. New > approaches to E/MEG data analysis have enabled the identification of > corresponding electrodynamic networks involving oscillatory rhythms. > However, the mechanisms underlying these disparate phenomena remain > unclear. > > We challenge the multi-modal neuroimaging community to put forward their > latest data addressing the question of how electrophysiological metrics > relate to BOLD fMRI, and how this advances our understanding of brain > function. Specifically we ask the questions: After comparing multiple > metrics of neural activity, which best explains the most variance of the > BOLD signal (for example, across trials, conditions, or subjects)? To what > extent is BOLD confounded by vascular non-linearity? To what extent are > electrophysiological metrics confounded by analysis techniques? And > finally, which aspect of E/MEG or BOLD activity best explains the true > cognitive processing (i.e. perception or behaviour)? > > ------------------------ > General information: > > Frontiers Research Topics are designed to be an organized, encyclopedic > coverage of a particular research area, and a forum for discussion and > debate. Contributions can be of different article types (Original Research, > Methods, Hypothesis& Theory, and others). > > Our Research Topic receives a dedicated homepage on the Frontiers website, > where contributing articles are accumulated and discussions can be easily > held. Once all articles are published, the topic will be compiled into an > eBook for widespread dissemination; it can be sent to all major foundations > that fund your research, to Frontiers' network of international > journalists, and to any list of organizations we propose. 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