**Functional connectivity: A multimodal approach for studying the interactions between brain areas** **Dante Mantini**<br/> *Movement Control and Neuroplasticity Research Group, KU Leuven, Belgium* **Haemy Lee Masson**<br/> *Laboratory of Biological Psychology, Department of Brain and Cognition, KU Leuven, Belgium* The brain is the most complex organ of the human body. To understand its functioning, advanced brain imaging techniques, such as functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG) and electroencephalography (EEG) have been developed in the last decades. These techniques allow us to non-invasively measure brain activity at different spatial and temporal scales, providing insight into the neuronal mechanisms associated with behavior. Coordinated brain dynamics both during task performance and resting state can be studied by using functional connectivity methods. Functional connectivity is typically measured using fMRI data, which are spatially accurate but are sampled only every few seconds, and reflect hemodynamic processes that are only indirectly linked to neuronal activity. On the other hand, few studies have alternatively used MEG and EEG for brain network imaging. MEG and EEG have high temporal resolution and provide direct measures of neural activity, but their applications are limited by the intrinsic uncertainty in source reconstructions. In this tutorial, we will introduce the main techniques used for the analysis of connectivity using fMRI, MEG and EEG, and will discuss the advantages and disadvantages to address specific research questions. We will then provide examples of the functional relevance of connectivity measures, relating them to behavioral performance both in healthy and diseased conditions. Learning objectives:<br/> 1. Describe the main techniques used for functional connectivity analysis 2. Understand the advantages and disadvantages of using fMRI, MEG and EEG for functional connectivity studies 3. Discuss the potential relationship between functional connectivity in the brain and behavior 4. Understand how to perform each step of basic and advanced functional connectivity analysis using the CONN toolbox (https://web.conn-toolbox.org).