Is optical imaging spectroscopy a viable measurement technique for the investigation of the negative BOLD phenomenon? A concurrent optical imaging spectroscopy and fMRI study at high field (7 T).
Bottom Line: Often accompanying positive BOLD fMRI signal changes are sustained negative signal changes.These experiments suggested that the negative BOLD signal in response to whisker stimulation was a result of an increase in deoxy-haemoglobin and reduced multi-unit activity in the deep cortical layers.Furthermore their study utilised a homogeneous tissue model in which is predominantly sensitive to haemodynamic changes in more superficial layers.
Affiliation: Centre for Signal Processing in Neuroimaging and Systems Neuroscience (SPiNSN), Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. A.J.Kennerley@shef.ac.ukShow MeSH
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Mentions: The spatial concordance between fMRI and 2D-OIS data was assessed by using the spatial 2D haemodynamic data in a Monte Carlo simulation of MR signal attenuation as in Martindale et al. (2008). The predicted BOLD signal was sub-sampled to the same spatial resolution as the fMRI BOLD data as described in the Material and methods section (Fig. 4 shows results from 2 representative z-score maps). As can be seen, for both positive and negative BOLD signal changes, there was concordance between measured and predicted activation maps despite differences in measurement resolution and technique.
Affiliation: Centre for Signal Processing in Neuroimaging and Systems Neuroscience (SPiNSN), Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. A.J.Kennerley@shef.ac.uk