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: Boorman et al. (2010) hypothesised that the deep layer negative BOLD was driven by deep layer decreases in neuronal activity. However, in that study fMRI and 2D-OIS were not performed concurrently. In that study they did concurrent electrophysiology and 2D-OIS and compared data to coronal fMRI from a different set of subjects. We found that our normalised haemodynamic responses showed very similar transients to their 2D-OIS data (Fig. 6). As we have now explicitly shown that such haemodynamic changes lead to a negative BOLD signal, the current data adds more support to their proposal regarding the neuronal origin of the negative BOLD.
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