Learning-dependent plasticity in the adult brain
Magnetic resonance imaging (MRI) -based morphometry is one of the most promising methods for non-invasive detection learning purposes plastic brain areas in the human field. The approach is based on the structure-function relationship: for every functional change there is a structural change, and vice versa. The structural changes in contrast to the functional changes are generally slightly delayed and significantly prolonged. Plastic areas can therefore be detected by MRI also at rest (in the absence of active learning process) and independent of acute brain activity over time. However, the exact nature of cellular processes underlying learning induced GM swelling is unknown. Studies with adult animals have demonstrated learning-related transient swelling of astrocytes and explaining the same pattern as observed in learning associated transient GM changes seen by MRI. On this basis, we hypothesized astrocytic enlargement as a major underlie mechanism to produce these GM volume changes. To test this hypothesis, we combined monocular deprivation (MD) based perceptual learning with longitudinal tracking of GM macro-structure changes in-vivo by MRI and deformation-based morphometry (DBM) accompanied by microscopic analyses of astrocytic and neuronal features in albino Wistar rats.