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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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Histology and functional activation maps. a) Post mortem histology showing stained barrel cortex and overlying vasculature. b) The same section with the vasculature removed. c) Live image of cortex outside of magnet allows easy visualisation of vasculature or comparison to images taken inside the magnet through the endoscope. d) BOLD fMRI SPM map showing positive BOLD changes in whisker barrel region and negative BOLD changes in surrounding somatosensory cortex in response to electrical stimulation of the whisker pad. e) Map of underlying HbT changes. f) Map of underlying Hbr changes. Using vascular net it is possible to warp the live images to the post mortem histology to overlay activation maps onto barrel stained sections for g) HbT and h) Hbr. Images indicate ‘positive’ BOLD is located in whisker barrels; negative BOLD in surrounding somatosensory cortex e.g. forepaw/hind paw.
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f0015: Histology and functional activation maps. a) Post mortem histology showing stained barrel cortex and overlying vasculature. b) The same section with the vasculature removed. c) Live image of cortex outside of magnet allows easy visualisation of vasculature or comparison to images taken inside the magnet through the endoscope. d) BOLD fMRI SPM map showing positive BOLD changes in whisker barrel region and negative BOLD changes in surrounding somatosensory cortex in response to electrical stimulation of the whisker pad. e) Map of underlying HbT changes. f) Map of underlying Hbr changes. Using vascular net it is possible to warp the live images to the post mortem histology to overlay activation maps onto barrel stained sections for g) HbT and h) Hbr. Images indicate ‘positive’ BOLD is located in whisker barrels; negative BOLD in surrounding somatosensory cortex e.g. forepaw/hind paw.

Mentions: Images of the stained slices can be linearly warped to one another where corresponding features are superimposed (Fig. 3a). The mathematical details of the warping have been described previously (Zheng et al., 2001). Penetrating blood vessels are used as fiducial markers between sections. Four matching points in each image defined an exact projection between the points; however, it was preferable to use a larger number of corresponding points to calculate the best (in least squares sense) projective transform. The surface section acts as a base template. The section immediately below is warped to fit over the surface section and then the section containing the barrel cortex (Fig. 3b) is warped to fit over the previously warped second section. The surface and warped barrel images are then superimposed to create a barrel map on the surface of the cortex to compare with the imaging results. For comparison with optical imaging results the surface section containing the stained vasculature is warped (using a similar method to that described above) to the vasculature seen in the endoscope images (Fig. 3c). The same warping parameters can then be applied to the histological section showing the stained somatosensory barrels and haemodynamic z-score maps from 2D-OIS superimposed to assess which cortical regions are active.


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)

Histology and functional activation maps. a) Post mortem histology showing stained barrel cortex and overlying vasculature. b) The same section with the vasculature removed. c) Live image of cortex outside of magnet allows easy visualisation of vasculature or comparison to images taken inside the magnet through the endoscope. d) BOLD fMRI SPM map showing positive BOLD changes in whisker barrel region and negative BOLD changes in surrounding somatosensory cortex in response to electrical stimulation of the whisker pad. e) Map of underlying HbT changes. f) Map of underlying Hbr changes. Using vascular net it is possible to warp the live images to the post mortem histology to overlay activation maps onto barrel stained sections for g) HbT and h) Hbr. Images indicate ‘positive’ BOLD is located in whisker barrels; negative BOLD in surrounding somatosensory cortex e.g. forepaw/hind paw.
© Copyright Policy
Related In: Results  -  Collection

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

f0015: Histology and functional activation maps. a) Post mortem histology showing stained barrel cortex and overlying vasculature. b) The same section with the vasculature removed. c) Live image of cortex outside of magnet allows easy visualisation of vasculature or comparison to images taken inside the magnet through the endoscope. d) BOLD fMRI SPM map showing positive BOLD changes in whisker barrel region and negative BOLD changes in surrounding somatosensory cortex in response to electrical stimulation of the whisker pad. e) Map of underlying HbT changes. f) Map of underlying Hbr changes. Using vascular net it is possible to warp the live images to the post mortem histology to overlay activation maps onto barrel stained sections for g) HbT and h) Hbr. Images indicate ‘positive’ BOLD is located in whisker barrels; negative BOLD in surrounding somatosensory cortex e.g. forepaw/hind paw.
Mentions: Images of the stained slices can be linearly warped to one another where corresponding features are superimposed (Fig. 3a). The mathematical details of the warping have been described previously (Zheng et al., 2001). Penetrating blood vessels are used as fiducial markers between sections. Four matching points in each image defined an exact projection between the points; however, it was preferable to use a larger number of corresponding points to calculate the best (in least squares sense) projective transform. The surface section acts as a base template. The section immediately below is warped to fit over the surface section and then the section containing the barrel cortex (Fig. 3b) is warped to fit over the previously warped second section. The surface and warped barrel images are then superimposed to create a barrel map on the surface of the cortex to compare with the imaging results. For comparison with optical imaging results the surface section containing the stained vasculature is warped (using a similar method to that described above) to the vasculature seen in the endoscope images (Fig. 3c). The same warping parameters can then be applied to the histological section showing the stained somatosensory barrels and haemodynamic z-score maps from 2D-OIS superimposed to assess which cortical regions are active.

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