New dimensions for brain mapping

The representation of memory in the brain is one of the unresolved questions in neuroscience. A key feature of learning and memory is the process of neuroplasticity--the ability of the brain to remodel structurally and functionally as a result of cognitive experience. Although the neurobiological basis of this process (that is, synaptic plasticity) is well established, the system level dynamics of neuroplasticity are still unclear. Recently, diffusion-weighted magnetic resonance imaging (DW-MRI), which can be carried out noninvasively in humans, provided a new approach to explore neuroplasticity. One of the parameters extracted from DW-MRI is mean diffusivity (MD) of water molecules, which is a biomarker of tissue microstructure (1).