The CAJAL course in Connectomics is an intensive three-week course that guides participants through the theory and practice of state-of the art methods to address pertinent questions in the field of structural/functional connectomics from mice to man. This goal will be achieved through a unique balance of lectures from world-wide experts in their respective fields to experimental demonstrations and hands-on laboratory work in small groups. During the course each participant will become familiar with a range of approaches, ranging from connectivity studies in the brain slice and in vivo in the behaving brain using electrophysiological, calcium imaging, optogenetic, viral trans-synaptic tracing, whole brain clearing and neuroimaging approaches with magnetic resonance imaging (functional and structural imaging) in both mice and human subjects (performed on the participants) and postmortem tissue.