Gray matter increase induced by practice correlates with task-specific activation: a combined functional and morphometric magnetic resonance imaging study - PubMed (original) (raw)

Comparative Study

Gray matter increase induced by practice correlates with task-specific activation: a combined functional and morphometric magnetic resonance imaging study

Rüdiger Ilg et al. J Neurosci. 2008.

Abstract

The neurophysiological basis of practice-induced gray matter increase is unclear. To study the relationship of practice-induced gray matter changes and neural activation, we conducted a combined longitudinal functional and morphometric (voxel-based morphometry) magnetic resonance imaging (MRI) study on mirror reading. Compared with normal reading, mirror reading resulted in an activation of the dorsolateral occipital cortex, medial occipital cortex, superior parietal cortex, medial and dorsolateral prefrontal cortex, as well as anterior insula and cerebellum. Daily practice of 15 min for 2 weeks resulted in an increased performance of mirror reading. After correction for pure performance effects, we found a practice-related decrease of activation at the right superior parietal cortex and increase of activation at the right dorsal occipital cortex. The longitudinal voxel-based morphometry analysis yielded an increase of gray matter in the right dorsolateral occipital cortex that corresponded to the peak of mirror-reading-specific activation. This confirms that short-term gray matter signal increase corresponds to task-specific processing. We speculate that practice-related gray matter signal changes in MRI are primarily related to synaptic remodeling within specific processing areas.

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Figures

Figure 1.

Figure 1.

Practice-related performance increase. Practice resulted in a significant increase in mirror-reading performance (mean ± SD, p < 0.001).

Figure 2.

Figure 2.

Practice-related changes in activation and gray matter. A, Clusters of activation and GM changes are displayed at a height threshold of 0.001 uncorrected and an extent threshold of 0.05 corrected. Mirror-reading-specific activation (green), practice-related decrease of activation (red), practice-related increase of activation (blue), and practice-related increase of GM (gray) are superimposed on a surface-rendered MNI template. Compared with normal reading, mirror reading resulted in a differential activation of bilateral dorsal occipital lobe (inferior, middle, and superior occipital gyrus), occipitotemporal cortex (fusiform gyrus), superior parietal cortex (bilateral superior parietal lobule, left intraparietal sulcus, bilateral precuneus, and left somatosensory cortex), medial and dorsolateral prefrontal cortex (left presupplementary motor area, right middle cingulate cortex, left frontal eye field, and bilateral precentral gyrus), right anterior insula, and cerebellum. The comparison of GM before and after practice shows a significant increase in GM in a subset of the regions (gray) activated in the right occipital cortex during mirror reading (green). B, The middle plot shows the maximum intensity projection of the GM increase. C, The right plot displays the GM signal change (as a percentage) of all voxels of the cluster (we divided the individual mean of the GM values of all voxels of the resulting cluster after practice by the individual mean of the GM values of the same voxels before practice; error bars indicate mean and SEM). The mean relative GM signal increase within the reported cluster was 5.1% (SEM, 1.6%) in the practice group and −0.3% in the control group (SEM, 1.3%).

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