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Quantitative assessment of visual cortex function with fMRI at 7 Tesla-test-retest variability.

Abd Hamid AI, Speck O, Hoffmann MB - Front Hum Neurosci (2015)

Bottom Line: We found a reduction between Sessions 1 and 2 for activated cortical surface area, between Sessions 1 and 3 for amplitude, and between Sessions 1 and 2/3 for coherence.The results do not support head motion as a major cause of the observed effect seen in Session 1, suggesting that cognitive effects were the underlying cause of change.This experimental design provides guidance in methodological issues of clinical longitudinal fMRI-studies, specifically regarding effects of subject experience.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Magnetic Resonance, Institute for Experimental Physics, Otto-von-Guericke University Magdeburg Magdeburg, Germany ; Department of Neurosciences, School of Medical Sciences Health Campus, Universiti Sains Malaysia Kubang Kerian, Malaysia.

ABSTRACT
fMRI-based retinotopic mapping was used to assess systematic variations in activated cortical surface area, amplitude, and coherence across sessions. Seven healthy subjects were scanned at 7 T in three separate sessions with intervals of 51.4 ± 5.4 days (Sessions 1 and 2) and 167.9 ± 24.4 days (Sessions 2 and 3). We found a reduction between Sessions 1 and 2 for activated cortical surface area, between Sessions 1 and 3 for amplitude, and between Sessions 1 and 2/3 for coherence. The results do not support head motion as a major cause of the observed effect seen in Session 1, suggesting that cognitive effects were the underlying cause of change. The phase correlations for both eccentricity and polar angle mapping were highly correlated between sessions, demonstrating the stability of the maps. Furthermore, the sensitivity in determining inter-session changes of cortical surface area, response amplitude, and coherence were, at a 5% significance level, estimated to be 1.5, 6, and 5%, respectively. Any future longitudinal fMRI study should carefully evaluate activation across sessions to determine the eligibility of inclusion of all time points. This experimental design provides guidance in methodological issues of clinical longitudinal fMRI-studies, specifically regarding effects of subject experience.

No MeSH data available.


Related in: MedlinePlus

Quantitative comparison of response amplitude (mean ± SEM) across sessions in V1, V2, and V3 for all visual stimulation conditions. Significant effects were observed for the factors session, stimulation condition, and visual area, and for the interaction of visual stimulation condition and visual area as detailed in Results.
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Figure 3: Quantitative comparison of response amplitude (mean ± SEM) across sessions in V1, V2, and V3 for all visual stimulation conditions. Significant effects were observed for the factors session, stimulation condition, and visual area, and for the interaction of visual stimulation condition and visual area as detailed in Results.

Mentions: In Figure 1 flat maps of the occipital pole are depicted for one representative individual to indicate the typical response topography obtained for eccentricity mapping, polar angle mapping, and full field stimulation [see Supplementary information (Figure S5), for other subjects]. A high degree of consistency of the obtained response patterns across sessions 1–3 is evident. For a quantitative account of the effects we determined for each visual area the activated cortical surface area, i.e., the voxels with significant fMRI-responses (p < 0.05; Figure 2). Subsequently we determined for these super-threshold regions the average amplitude and coherence separately for each visual area and session (Figures 3, 4). The significance of the effects was determined with separate Three-Way repeated measures ANOVAs [factors: session, stimulation condition, visual area; see Table 1 and Supplementary information (Figures S6–S8)]. Initial Three-Way repeated measures ANOVAs comparing the dorsal and ventral parts of the early visual areas did not indicate any significant effect (individual and interaction factors) on the activated cortical surface area, response amplitude, and coherence (p > 0.05). Therefore, the dorsal and ventral parts of the early visual areas V1, V2, and V3 were combined for further analysis.


Quantitative assessment of visual cortex function with fMRI at 7 Tesla-test-retest variability.

Abd Hamid AI, Speck O, Hoffmann MB - Front Hum Neurosci (2015)

Quantitative comparison of response amplitude (mean ± SEM) across sessions in V1, V2, and V3 for all visual stimulation conditions. Significant effects were observed for the factors session, stimulation condition, and visual area, and for the interaction of visual stimulation condition and visual area as detailed in Results.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555013&req=5

Figure 3: Quantitative comparison of response amplitude (mean ± SEM) across sessions in V1, V2, and V3 for all visual stimulation conditions. Significant effects were observed for the factors session, stimulation condition, and visual area, and for the interaction of visual stimulation condition and visual area as detailed in Results.
Mentions: In Figure 1 flat maps of the occipital pole are depicted for one representative individual to indicate the typical response topography obtained for eccentricity mapping, polar angle mapping, and full field stimulation [see Supplementary information (Figure S5), for other subjects]. A high degree of consistency of the obtained response patterns across sessions 1–3 is evident. For a quantitative account of the effects we determined for each visual area the activated cortical surface area, i.e., the voxels with significant fMRI-responses (p < 0.05; Figure 2). Subsequently we determined for these super-threshold regions the average amplitude and coherence separately for each visual area and session (Figures 3, 4). The significance of the effects was determined with separate Three-Way repeated measures ANOVAs [factors: session, stimulation condition, visual area; see Table 1 and Supplementary information (Figures S6–S8)]. Initial Three-Way repeated measures ANOVAs comparing the dorsal and ventral parts of the early visual areas did not indicate any significant effect (individual and interaction factors) on the activated cortical surface area, response amplitude, and coherence (p > 0.05). Therefore, the dorsal and ventral parts of the early visual areas V1, V2, and V3 were combined for further analysis.

Bottom Line: We found a reduction between Sessions 1 and 2 for activated cortical surface area, between Sessions 1 and 3 for amplitude, and between Sessions 1 and 2/3 for coherence.The results do not support head motion as a major cause of the observed effect seen in Session 1, suggesting that cognitive effects were the underlying cause of change.This experimental design provides guidance in methodological issues of clinical longitudinal fMRI-studies, specifically regarding effects of subject experience.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Magnetic Resonance, Institute for Experimental Physics, Otto-von-Guericke University Magdeburg Magdeburg, Germany ; Department of Neurosciences, School of Medical Sciences Health Campus, Universiti Sains Malaysia Kubang Kerian, Malaysia.

ABSTRACT
fMRI-based retinotopic mapping was used to assess systematic variations in activated cortical surface area, amplitude, and coherence across sessions. Seven healthy subjects were scanned at 7 T in three separate sessions with intervals of 51.4 ± 5.4 days (Sessions 1 and 2) and 167.9 ± 24.4 days (Sessions 2 and 3). We found a reduction between Sessions 1 and 2 for activated cortical surface area, between Sessions 1 and 3 for amplitude, and between Sessions 1 and 2/3 for coherence. The results do not support head motion as a major cause of the observed effect seen in Session 1, suggesting that cognitive effects were the underlying cause of change. The phase correlations for both eccentricity and polar angle mapping were highly correlated between sessions, demonstrating the stability of the maps. Furthermore, the sensitivity in determining inter-session changes of cortical surface area, response amplitude, and coherence were, at a 5% significance level, estimated to be 1.5, 6, and 5%, respectively. Any future longitudinal fMRI study should carefully evaluate activation across sessions to determine the eligibility of inclusion of all time points. This experimental design provides guidance in methodological issues of clinical longitudinal fMRI-studies, specifically regarding effects of subject experience.

No MeSH data available.


Related in: MedlinePlus