Neuroimaging allows to characterize patterns of neural activity that specifically correlate with mental functions such as perception, memory, and emotions. However, conventional imaging experiments are purely observational and cannot be used to establish a causal link between brain activity and the mental functions that are studied. Here I propose using a new approach to investigate causal links between the two: I will use real-time functional magnetic resonance imaging (rtfMRI) with neurofeedback to teach participants to voluntarily regulate either the level of brain activity or of the functional coupling of brain areas. I will then test how self-regulation of activity (or connectivity) affects perception and memory, thus allowing an understanding of the causal relationship between the two.Using neurofeedback, I will (a) test how self-regulating brain connectivity in the visual cortex affects visual feature integration, (b) explore the use of neurofeedback to treat patients with visual hemispatial neglect, which is a common and disabling neurological disorder, and (c) use neurofeedback to manipulate visual memory consolidation by indirectly affecting neurotransmitter systems. Besides these three main projects, I will significantly advance the field of rtfMRI-based neurofeedback by (a) extending the neurofeedback approach to control functional brain networks instead of only a single area (connectivity feedback), and by investigating (b) how long learned self-regulation is maintained without further training, (c) if self-regulation causes structural changes in brain anatomy, and (d) how important strategy guidelines are for learning self-regulation.These projects will provide new insights into the causal links between brain activation and mental functions, and they will also provide important methodological innovations which will lay the foundation for valuable clinical applications.