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Diffusion MRI of structural brain plasticity induced by a learning and memory task.

Blumenfeld-Katzir T, Pasternak O, Dagan M, Assaf Y - PLoS ONE (2011)

Bottom Line: Here we used diffusion tensor imaging (DTI) to examine the microstructural manifestations of neuroplasticity in rats that performed a spatial navigation task.We found that DTI can be used to define the selective localization of neuroplasticity induced by different tasks and that this process is age-dependent in cingulate cortex and corpus callosum and age-independent in the dentate gyrus.We relate the observed DTI changes to the structural plasticity that occurs in astrocytes and discuss the potential of MRI for probing structural neuroplasticity and hence indirectly localizing LTP.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.

ABSTRACT

Background: Activity-induced structural remodeling of dendritic spines and glial cells was recently proposed as an important factor in neuroplasticity and suggested to accompany the induction of long-term potentiation (LTP). Although T1 and diffusion MRI have been used to study structural changes resulting from long-term training, the cellular basis of the findings obtained and their relationship to neuroplasticity are poorly understood.

Methodology/principal finding: Here we used diffusion tensor imaging (DTI) to examine the microstructural manifestations of neuroplasticity in rats that performed a spatial navigation task. We found that DTI can be used to define the selective localization of neuroplasticity induced by different tasks and that this process is age-dependent in cingulate cortex and corpus callosum and age-independent in the dentate gyrus.

Conclusion/significance: We relate the observed DTI changes to the structural plasticity that occurs in astrocytes and discuss the potential of MRI for probing structural neuroplasticity and hence indirectly localizing LTP.

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Age dependency of the changes in diffusion tensor imaging induced by spatial learning.(a) and (b) Statistical parametric maps of the scan time main effect over the three group L subgroups (rats that underwent the water maze task at the age of 1, 4, or 12 months) for ADC and FA, respectively. Voxels that exceed a statistical threshold of P<0.05 (non-corrected) are colored according to the threshold they exceeded (see color scale), while those that did not exceed the threshold are not colored. We report only on regional clusters that exceeded a statistical threshold of P<0.05 corrected for multiple comparisons (using the FDR method); these regions are shown in the insets. The regional pattern of the main effect (in both the ADC and the FA maps) includes the dentate gyrus (DG) and cingulate cortex as well as the corpus callosum. Post-hoc analysis of the main effects revealed that in some regions the magnitude of DTI changes between the two scans was similar across ages. Examples are reduction in ADC in the in the DG (c). Other regions show an age-dependent relationship in which effects were more pronounced in younger than in older mice. This was observed in the CG (d) and the corpus callosum (e).
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pone-0020678-g005: Age dependency of the changes in diffusion tensor imaging induced by spatial learning.(a) and (b) Statistical parametric maps of the scan time main effect over the three group L subgroups (rats that underwent the water maze task at the age of 1, 4, or 12 months) for ADC and FA, respectively. Voxels that exceed a statistical threshold of P<0.05 (non-corrected) are colored according to the threshold they exceeded (see color scale), while those that did not exceed the threshold are not colored. We report only on regional clusters that exceeded a statistical threshold of P<0.05 corrected for multiple comparisons (using the FDR method); these regions are shown in the insets. The regional pattern of the main effect (in both the ADC and the FA maps) includes the dentate gyrus (DG) and cingulate cortex as well as the corpus callosum. Post-hoc analysis of the main effects revealed that in some regions the magnitude of DTI changes between the two scans was similar across ages. Examples are reduction in ADC in the in the DG (c). Other regions show an age-dependent relationship in which effects were more pronounced in younger than in older mice. This was observed in the CG (d) and the corpus callosum (e).

Mentions: In the following analysis we probed the age dependency of changes in DTI indices induced by learning and memory. This was done by ANOVA with two factors: age (1, 4, and 12 months) and scan time (1st and 2nd scans) with repeated measures on the second factor. Results of the main effect of scan time over the three age subgroups are given in Figure 5 for both ADC and FA. The regions that exceeded the statistical threshold for the scan/time main effect (Fig. 5) were similar to the regions found in the interaction effect between the learning and the control groups at 4 months (Fig. 1). These results indicate that the regional pattern of DTI changes induced by learning and memory is not altered with age. Regional analysis revealed that in some regions (DG) the effect was similar in magnitude for all age groups (Fig. 5c), while in others (CG) the effect was stronger for the younger groups (Fig. 5d) and decreased with age. In addition, changes in FA in white matter regions (CC) were more pronounced in the younger groups (Fig. 5e) and decreased with age.


Diffusion MRI of structural brain plasticity induced by a learning and memory task.

Blumenfeld-Katzir T, Pasternak O, Dagan M, Assaf Y - PLoS ONE (2011)

Age dependency of the changes in diffusion tensor imaging induced by spatial learning.(a) and (b) Statistical parametric maps of the scan time main effect over the three group L subgroups (rats that underwent the water maze task at the age of 1, 4, or 12 months) for ADC and FA, respectively. Voxels that exceed a statistical threshold of P<0.05 (non-corrected) are colored according to the threshold they exceeded (see color scale), while those that did not exceed the threshold are not colored. We report only on regional clusters that exceeded a statistical threshold of P<0.05 corrected for multiple comparisons (using the FDR method); these regions are shown in the insets. The regional pattern of the main effect (in both the ADC and the FA maps) includes the dentate gyrus (DG) and cingulate cortex as well as the corpus callosum. Post-hoc analysis of the main effects revealed that in some regions the magnitude of DTI changes between the two scans was similar across ages. Examples are reduction in ADC in the in the DG (c). Other regions show an age-dependent relationship in which effects were more pronounced in younger than in older mice. This was observed in the CG (d) and the corpus callosum (e).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3119075&req=5

pone-0020678-g005: Age dependency of the changes in diffusion tensor imaging induced by spatial learning.(a) and (b) Statistical parametric maps of the scan time main effect over the three group L subgroups (rats that underwent the water maze task at the age of 1, 4, or 12 months) for ADC and FA, respectively. Voxels that exceed a statistical threshold of P<0.05 (non-corrected) are colored according to the threshold they exceeded (see color scale), while those that did not exceed the threshold are not colored. We report only on regional clusters that exceeded a statistical threshold of P<0.05 corrected for multiple comparisons (using the FDR method); these regions are shown in the insets. The regional pattern of the main effect (in both the ADC and the FA maps) includes the dentate gyrus (DG) and cingulate cortex as well as the corpus callosum. Post-hoc analysis of the main effects revealed that in some regions the magnitude of DTI changes between the two scans was similar across ages. Examples are reduction in ADC in the in the DG (c). Other regions show an age-dependent relationship in which effects were more pronounced in younger than in older mice. This was observed in the CG (d) and the corpus callosum (e).
Mentions: In the following analysis we probed the age dependency of changes in DTI indices induced by learning and memory. This was done by ANOVA with two factors: age (1, 4, and 12 months) and scan time (1st and 2nd scans) with repeated measures on the second factor. Results of the main effect of scan time over the three age subgroups are given in Figure 5 for both ADC and FA. The regions that exceeded the statistical threshold for the scan/time main effect (Fig. 5) were similar to the regions found in the interaction effect between the learning and the control groups at 4 months (Fig. 1). These results indicate that the regional pattern of DTI changes induced by learning and memory is not altered with age. Regional analysis revealed that in some regions (DG) the effect was similar in magnitude for all age groups (Fig. 5c), while in others (CG) the effect was stronger for the younger groups (Fig. 5d) and decreased with age. In addition, changes in FA in white matter regions (CC) were more pronounced in the younger groups (Fig. 5e) and decreased with age.

Bottom Line: Here we used diffusion tensor imaging (DTI) to examine the microstructural manifestations of neuroplasticity in rats that performed a spatial navigation task.We found that DTI can be used to define the selective localization of neuroplasticity induced by different tasks and that this process is age-dependent in cingulate cortex and corpus callosum and age-independent in the dentate gyrus.We relate the observed DTI changes to the structural plasticity that occurs in astrocytes and discuss the potential of MRI for probing structural neuroplasticity and hence indirectly localizing LTP.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.

ABSTRACT

Background: Activity-induced structural remodeling of dendritic spines and glial cells was recently proposed as an important factor in neuroplasticity and suggested to accompany the induction of long-term potentiation (LTP). Although T1 and diffusion MRI have been used to study structural changes resulting from long-term training, the cellular basis of the findings obtained and their relationship to neuroplasticity are poorly understood.

Methodology/principal finding: Here we used diffusion tensor imaging (DTI) to examine the microstructural manifestations of neuroplasticity in rats that performed a spatial navigation task. We found that DTI can be used to define the selective localization of neuroplasticity induced by different tasks and that this process is age-dependent in cingulate cortex and corpus callosum and age-independent in the dentate gyrus.

Conclusion/significance: We relate the observed DTI changes to the structural plasticity that occurs in astrocytes and discuss the potential of MRI for probing structural neuroplasticity and hence indirectly localizing LTP.

Show MeSH