Konstantinos Meletis, PhD, is a professor of systems neuroscience at the Karolinska Institute. He is an expert in the study of circuit organization and the role of neuron subtypes in motivated behaviors. His laboratory has developed and applied a number of methods to map circuit organization and function, including advanced molecular methods to determine gene activity patterns in cells and tissue at large scale, the use of genetically modified viruses to define cell-type specific connectivity and imaging and optogenetic approaches to define the role of neurons in aversion and motivation. During his PhD studies at the Karolinska Institute, Dr. Meletis developed methods to trace the lineage of stem and progenitor cells in the adult nervous system and studied their response to injury. In his postdoctoral training at Massachusetts Institute of Technology, he used mouse models and optogenetics to study the function of neuron subtypes in psychiatric disorders.