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The BOLD response and the gamma oscillations respond differently than evoked potentials: an interleaved EEG-fMRI study.

Foucher JR, Otzenberger H, Gounot D - BMC Neurosci (2003)

Bottom Line: Both Targets and Novels triggered a P300, of larger amplitude in the Novel condition.EEG event-related oscillations in the gamma band (32-38 Hz) reacted in a way similar to the BOLD response.Those results provide further arguments for a closer relationship between fast oscillations and the BOLD signal, than between evoked potentials and the BOLD signal.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinique Psychiatrique-INSERM U405, Hôpitaux Universitaires-BP 406-67091 Strasbourg Cedex-France. jf@evc.net

ABSTRACT

Background: The integration of EEG and fMRI is attractive because of their complementary precision regarding time and space. But the relationship between the indirect hemodynamic fMRI signal and the more direct EEG signal is uncertain. Event-related EEG responses can be analyzed in two different ways, reflecting two different kinds of brain activity: evoked, i.e. phase-locked to the stimulus, such as evoked potentials, or induced, i.e. non phase-locked to the stimulus such as event-related oscillations. In order to determine which kind of EEG activity was more closely related with fMRI, EEG and fMRI signals were acquired together, while subjects were presented with two kinds of rare events intermingled with frequent distractors. Target events had to be signaled by pressing a button and Novel events had to be ignored.

Results: Both Targets and Novels triggered a P300, of larger amplitude in the Novel condition. On the opposite, the fMRI BOLD response was stronger in the Target condition. EEG event-related oscillations in the gamma band (32-38 Hz) reacted in a way similar to the BOLD response.

Conclusions: The reasons for such opposite differential reactivity between oscillations / fMRI on the one hand, and evoked potentials on the other, are discussed in the paper. Those results provide further arguments for a closer relationship between fast oscillations and the BOLD signal, than between evoked potentials and the BOLD signal.

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fMRI results Lateral views of the normalized brain of 1 subject, colored as a function of contrast: Target-related activation (red and "X" marks), Target-related deactivation (green and "no-smoking" marks), and Novel-related activation (blue) (thresholds p ≤ 0.001, 100 voxel). The network that deactivated on target presentation comprised the superior frontal sulcus (SFS), the parietal cortex and the inferior frontal sulcus (IFS). The latter is supposed to be related with distractor inhibition since its posterior part is over-activated by Novels together with the posterior parietal cortex (PP). The network activated by targets comprised the supra-marginal gyrus (SMG) and the inferior frontal gyrus (IFG). Note that the TPJ is composed of the SMG (BA 40) in its upper part, and of the superior temporal gyrus (BA 39) in its lower part. The peristimulus BOLD signals are displayed for each relevant region for Targets (red), Novels (blue) and frequent distractors (gray). The curves are computed by simple averaging after regressing the other condition effect and removing high- and low-frequency components. The variation in signal intensity is indicated as a percentage of the MRI signal, and the scale is similar for all except the parietal area. Notice the balance between the anterior cingulate area (ACA) and the posterior cingulate area (PCA). Those charts also exclude the possibility for a threshold effect to account for the absence of Novel-related activation of the EXO network.
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Figure 1: fMRI results Lateral views of the normalized brain of 1 subject, colored as a function of contrast: Target-related activation (red and "X" marks), Target-related deactivation (green and "no-smoking" marks), and Novel-related activation (blue) (thresholds p ≤ 0.001, 100 voxel). The network that deactivated on target presentation comprised the superior frontal sulcus (SFS), the parietal cortex and the inferior frontal sulcus (IFS). The latter is supposed to be related with distractor inhibition since its posterior part is over-activated by Novels together with the posterior parietal cortex (PP). The network activated by targets comprised the supra-marginal gyrus (SMG) and the inferior frontal gyrus (IFG). Note that the TPJ is composed of the SMG (BA 40) in its upper part, and of the superior temporal gyrus (BA 39) in its lower part. The peristimulus BOLD signals are displayed for each relevant region for Targets (red), Novels (blue) and frequent distractors (gray). The curves are computed by simple averaging after regressing the other condition effect and removing high- and low-frequency components. The variation in signal intensity is indicated as a percentage of the MRI signal, and the scale is similar for all except the parietal area. Notice the balance between the anterior cingulate area (ACA) and the posterior cingulate area (PCA). Those charts also exclude the possibility for a threshold effect to account for the absence of Novel-related activation of the EXO network.

Mentions: The Target condition is related with activations especially in regions said to be the sources of the P300: the inferior frontal gyrus bilaterally and the right temporo-parietal junction (posterior supramarginal gyrus). Other regions were also activated: the right antero-basal frontal region (BA 10), the anterior cingulate and the supplementary motor areas, bilaterally, the inferior parietal lobule and intraparietal sulcus, and the left central sulcus and thalamus (pulvinar and dorso-median nuclei) (table 1 – see Additional file 1, fig. 1). Deactivated regions in the Target condition, were the superior frontal sulcus bilaterally, the left inferior frontal gyrus, the right posterior insula, the precuneus and the posterior cingulate bilaterally, the posterior part of the superior temporal sulcus, and infero-temporal areas (table 1 – see Additional file 1, fig. 1).


The BOLD response and the gamma oscillations respond differently than evoked potentials: an interleaved EEG-fMRI study.

Foucher JR, Otzenberger H, Gounot D - BMC Neurosci (2003)

fMRI results Lateral views of the normalized brain of 1 subject, colored as a function of contrast: Target-related activation (red and "X" marks), Target-related deactivation (green and "no-smoking" marks), and Novel-related activation (blue) (thresholds p ≤ 0.001, 100 voxel). The network that deactivated on target presentation comprised the superior frontal sulcus (SFS), the parietal cortex and the inferior frontal sulcus (IFS). The latter is supposed to be related with distractor inhibition since its posterior part is over-activated by Novels together with the posterior parietal cortex (PP). The network activated by targets comprised the supra-marginal gyrus (SMG) and the inferior frontal gyrus (IFG). Note that the TPJ is composed of the SMG (BA 40) in its upper part, and of the superior temporal gyrus (BA 39) in its lower part. The peristimulus BOLD signals are displayed for each relevant region for Targets (red), Novels (blue) and frequent distractors (gray). The curves are computed by simple averaging after regressing the other condition effect and removing high- and low-frequency components. The variation in signal intensity is indicated as a percentage of the MRI signal, and the scale is similar for all except the parietal area. Notice the balance between the anterior cingulate area (ACA) and the posterior cingulate area (PCA). Those charts also exclude the possibility for a threshold effect to account for the absence of Novel-related activation of the EXO network.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC222904&req=5

Figure 1: fMRI results Lateral views of the normalized brain of 1 subject, colored as a function of contrast: Target-related activation (red and "X" marks), Target-related deactivation (green and "no-smoking" marks), and Novel-related activation (blue) (thresholds p ≤ 0.001, 100 voxel). The network that deactivated on target presentation comprised the superior frontal sulcus (SFS), the parietal cortex and the inferior frontal sulcus (IFS). The latter is supposed to be related with distractor inhibition since its posterior part is over-activated by Novels together with the posterior parietal cortex (PP). The network activated by targets comprised the supra-marginal gyrus (SMG) and the inferior frontal gyrus (IFG). Note that the TPJ is composed of the SMG (BA 40) in its upper part, and of the superior temporal gyrus (BA 39) in its lower part. The peristimulus BOLD signals are displayed for each relevant region for Targets (red), Novels (blue) and frequent distractors (gray). The curves are computed by simple averaging after regressing the other condition effect and removing high- and low-frequency components. The variation in signal intensity is indicated as a percentage of the MRI signal, and the scale is similar for all except the parietal area. Notice the balance between the anterior cingulate area (ACA) and the posterior cingulate area (PCA). Those charts also exclude the possibility for a threshold effect to account for the absence of Novel-related activation of the EXO network.
Mentions: The Target condition is related with activations especially in regions said to be the sources of the P300: the inferior frontal gyrus bilaterally and the right temporo-parietal junction (posterior supramarginal gyrus). Other regions were also activated: the right antero-basal frontal region (BA 10), the anterior cingulate and the supplementary motor areas, bilaterally, the inferior parietal lobule and intraparietal sulcus, and the left central sulcus and thalamus (pulvinar and dorso-median nuclei) (table 1 – see Additional file 1, fig. 1). Deactivated regions in the Target condition, were the superior frontal sulcus bilaterally, the left inferior frontal gyrus, the right posterior insula, the precuneus and the posterior cingulate bilaterally, the posterior part of the superior temporal sulcus, and infero-temporal areas (table 1 – see Additional file 1, fig. 1).

Bottom Line: Both Targets and Novels triggered a P300, of larger amplitude in the Novel condition.EEG event-related oscillations in the gamma band (32-38 Hz) reacted in a way similar to the BOLD response.Those results provide further arguments for a closer relationship between fast oscillations and the BOLD signal, than between evoked potentials and the BOLD signal.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinique Psychiatrique-INSERM U405, Hôpitaux Universitaires-BP 406-67091 Strasbourg Cedex-France. jf@evc.net

ABSTRACT

Background: The integration of EEG and fMRI is attractive because of their complementary precision regarding time and space. But the relationship between the indirect hemodynamic fMRI signal and the more direct EEG signal is uncertain. Event-related EEG responses can be analyzed in two different ways, reflecting two different kinds of brain activity: evoked, i.e. phase-locked to the stimulus, such as evoked potentials, or induced, i.e. non phase-locked to the stimulus such as event-related oscillations. In order to determine which kind of EEG activity was more closely related with fMRI, EEG and fMRI signals were acquired together, while subjects were presented with two kinds of rare events intermingled with frequent distractors. Target events had to be signaled by pressing a button and Novel events had to be ignored.

Results: Both Targets and Novels triggered a P300, of larger amplitude in the Novel condition. On the opposite, the fMRI BOLD response was stronger in the Target condition. EEG event-related oscillations in the gamma band (32-38 Hz) reacted in a way similar to the BOLD response.

Conclusions: The reasons for such opposite differential reactivity between oscillations / fMRI on the one hand, and evoked potentials on the other, are discussed in the paper. Those results provide further arguments for a closer relationship between fast oscillations and the BOLD signal, than between evoked potentials and the BOLD signal.

Show MeSH
Related in: MedlinePlus