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Interpreting Deactivations in Neuroimaging

Authors
Journal
Frontiers in Psychology
1664-1078
Publisher
Frontiers Media SA
Publication Date
Volume
3
Identifiers
DOI: 10.3389/fpsyg.2012.00027
Keywords
  • Psychology
  • Opinion Article
Disciplines
  • Biology
  • Medicine
  • Philosophy
  • Psychology

Abstract

Interpreting deactivations in neuroimaging Interpreting deactivations in neuroimaging Dave J. Hayes1* and Adrianne G. Huxtable2 1 Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, Ottawa, ON, Canada 2 Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA *Correspondence: [email protected] Functional magnetic resonance imaging (fMRI) is a relatively young tool for under- standing how the brain’s activities contrib- ute to physical and psychological processes. In the roughly 20 years since its introduc- tion, fMRI has developed at an astound- ing rate regarding advances in both the acquisition of images, as well as improved post-acquisition analysis (Bandettini, 2011). Blood oxygenation level depend- ent (BOLD) activity is its key measure and most studies rely on contrasts between two conditions of interest (e.g., BOLD signal during exposure to painful stimuli > signal during exposure to non-painful stimuli) to identify regions of functional significance. Alternately, electrophysiological techniques provide direct measures of neural activ- ity in comparison to neuroimaging tech- niques. Deciphering the precise activity of the brain, in normal and pathological conditions, is of paramount importance; both neuroimaging and electrophysiologi- cal techniques will likely be crucial in this regard. The BOLD signal has been thought of as a correlate of local synaptic activity (neuronal and possibly glial activity; e.g., Schummers et al., 2008), and recent studies using combined optogenetic imaging and fMRI have supported this central assump- tion (Lee et al., 2010). The hemodynamic response that underpins the BOLD signal is predominantly based on the displace- ment of deoxyhemoglobin by inflowing oxygenated hemoglobin. As such, BOLD signals rely heavily on blood volume and flow, as well as on oxygen consumption, all factors which are generally (but not always) positively c

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