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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).

Kennerley AJ, Mayhew JE, Boorman L, Zheng Y, Berwick J - Neuroimage (2012)

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.

View Article: PubMed Central - PubMed

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

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Time series data of a) positive and negative BOLD measured with fMRI, b) the concurrent underlying Hbr measurements from both regions. The whisker barrel (positive BOLD) region shows the ‘deoxy dip’ the surrounding cortical (negative BOLD) region does not (insert). 2D-OIS haemodynamic data for c) the whisker barrel/positive BOLD and d) surrounding cortex/negative BOLD region is analysed with both heterogeneous and homogeneous tissue models. The former shows increased magnitude of Hbr changes. Haemodynamic data is input into a MCS of MR signal attenuation to predict e) the positive BOLD and f) the negative BOLD using both hetero- and homogeneous tissue models. Predictions are for the extra-vascular space assuming a mean vessel radius between 3 and 20 μm (generating the prediction envelopes shown). For both regions we find good agreement between fMRI measurements and model predictions only when using the heterogeneous tissue model in 2D-OIS spectral analysis.
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f0025: Time series data of a) positive and negative BOLD measured with fMRI, b) the concurrent underlying Hbr measurements from both regions. The whisker barrel (positive BOLD) region shows the ‘deoxy dip’ the surrounding cortical (negative BOLD) region does not (insert). 2D-OIS haemodynamic data for c) the whisker barrel/positive BOLD and d) surrounding cortex/negative BOLD region is analysed with both heterogeneous and homogeneous tissue models. The former shows increased magnitude of Hbr changes. Haemodynamic data is input into a MCS of MR signal attenuation to predict e) the positive BOLD and f) the negative BOLD using both hetero- and homogeneous tissue models. Predictions are for the extra-vascular space assuming a mean vessel radius between 3 and 20 μm (generating the prediction envelopes shown). For both regions we find good agreement between fMRI measurements and model predictions only when using the heterogeneous tissue model in 2D-OIS spectral analysis.

Mentions: Region of interest masking of threshold activation maps (whisker and surrounding cortex) was used to obtain time series data from a mixed region of arterioles, parenchyma and venules (Fig. 5). The average time series (mean across all subjects), of the BOLD fMRI signal showed a positive signal change in the whisker barrel cortex in response to electrical stimulation of the whisker pad (Fig. 5a). The response peaked with a magnitude of ~ 3.5% at 4 s after stimulus onset, falling to a plateau (~ 1.5%) which was maintained until stimulus offset. In regions surrounding the whisker barrel cortex the time series showed reliable negative BOLD peaking with a magnitude of ~−1% at 8 s (Fig. 5a).


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).

Kennerley AJ, Mayhew JE, Boorman L, Zheng Y, Berwick J - Neuroimage (2012)

Time series data of a) positive and negative BOLD measured with fMRI, b) the concurrent underlying Hbr measurements from both regions. The whisker barrel (positive BOLD) region shows the ‘deoxy dip’ the surrounding cortical (negative BOLD) region does not (insert). 2D-OIS haemodynamic data for c) the whisker barrel/positive BOLD and d) surrounding cortex/negative BOLD region is analysed with both heterogeneous and homogeneous tissue models. The former shows increased magnitude of Hbr changes. Haemodynamic data is input into a MCS of MR signal attenuation to predict e) the positive BOLD and f) the negative BOLD using both hetero- and homogeneous tissue models. Predictions are for the extra-vascular space assuming a mean vessel radius between 3 and 20 μm (generating the prediction envelopes shown). For both regions we find good agreement between fMRI measurements and model predictions only when using the heterogeneous tissue model in 2D-OIS spectral analysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368428&req=5

f0025: Time series data of a) positive and negative BOLD measured with fMRI, b) the concurrent underlying Hbr measurements from both regions. The whisker barrel (positive BOLD) region shows the ‘deoxy dip’ the surrounding cortical (negative BOLD) region does not (insert). 2D-OIS haemodynamic data for c) the whisker barrel/positive BOLD and d) surrounding cortex/negative BOLD region is analysed with both heterogeneous and homogeneous tissue models. The former shows increased magnitude of Hbr changes. Haemodynamic data is input into a MCS of MR signal attenuation to predict e) the positive BOLD and f) the negative BOLD using both hetero- and homogeneous tissue models. Predictions are for the extra-vascular space assuming a mean vessel radius between 3 and 20 μm (generating the prediction envelopes shown). For both regions we find good agreement between fMRI measurements and model predictions only when using the heterogeneous tissue model in 2D-OIS spectral analysis.
Mentions: Region of interest masking of threshold activation maps (whisker and surrounding cortex) was used to obtain time series data from a mixed region of arterioles, parenchyma and venules (Fig. 5). The average time series (mean across all subjects), of the BOLD fMRI signal showed a positive signal change in the whisker barrel cortex in response to electrical stimulation of the whisker pad (Fig. 5a). The response peaked with a magnitude of ~ 3.5% at 4 s after stimulus onset, falling to a plateau (~ 1.5%) which was maintained until stimulus offset. In regions surrounding the whisker barrel cortex the time series showed reliable negative BOLD peaking with a magnitude of ~−1% at 8 s (Fig. 5a).

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.

View Article: PubMed Central - PubMed

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

Show MeSH
Related in: MedlinePlus