Neuroscience Methods for Investigating Brain Plasticity (Chapter to appear in The Oxford Handbook of Cognitive Enhancement and Brain Plasticity)

The brain's ability to change – its plasticity – in response to new environments, experiences or damage, is the foundation of cognition. Unravelling the mechanisms of plasticity in humans is a central goal for neuroscience. This chapter provides an overview of common methods used to study structural and functional brain plasticity in humans. The main structural methods we discuss are T1-weighted Magnetic Resonance Imaging (MRI), which is widely used to track anatomical changes in the brain, and Positron Emission Tomography (PET), which allows investigation of neurochemical processes, such as receptor density changes. The section on functional plasticity evolves around (T2*-weighted) functional MRI (fMRI) and attempts to provide an overview of analysis methods and MRI sequences that can be used to study functional changes in the brain, including resting state analysis, univariate and multivariate analyses. We further provide a short summary of non-invasive brain stimulation methods that, combined with other structural or functional methods, have proven to be useful tools for inducing and measuring plasticity. We also address limitations of these methods, in particular for tracking fast or microscopic changes and discuss the importance of a good study design that ensures measurements match the research question. This emphasises the benefits of combining non-invasive brain imaging with longitudinal designs to reveal the nature of plasticity in humans.