We would like to invite you to consider contributing an article to the Frontiers research topic “Neuromodulation of Circuits in Brain Health and Disease”. The research topic is hosted by: Srikanth Ramaswamy, Henry Markram, Mriganka Sur, Anita Disney, Menahem Segal, Michael E Hasselmo, Seung-Hee Lee, Alexander Thiele, and Amy F T Arnsten. The overarching goal of this research topic is to rekindle the field of neuromodulation by providing a state-of-the-art and unifying view of the mechanisms by which a diversity of neurotransmitters and neuromodulators such as acetylcholine (ACh), dopamine (DA), noradrenaline (NE), serotonin (5-HT) and histamine (HA) - the master switches - control genes, proteins, neurons and glia, dendrites, synapses, and emergent states in neural circuits across different brain regions in health and disease. Concretely, our hope is that this research topic will a) establish an up to date view of neuromodulatory control of brain states by ACh, DA, NE, 5-HT, and HA that is encyclopedic in breadth and depth, and b) establish future research directions. Additionally, we also plan to organize a conference to discuss the state-of-the-art and future of neuromodulation research. Contributing authors to this research topic will be invited to present at the conference. The conference will be held at the EPFL campus in Lausanne, Switzerland in September 2017 and further details will be sent out in due course. Frontiers research topics initially require the submission of an abstract of your work, which will be considered by the topic editors to determine if it falls within the goals of the research topic. Approved abstracts will then be invited to submit a complete manuscript. Depending on the article type, Frontiers has article processing charges (APCs). They range from free to 2490$ for original research articles or reviews (please see http://home.frontiersin.org/about/publishing-fees). If submitted to a Research Topic within the deadline there is a 15% reduction for some article types. Frontiers also has a waiver program so that APCs do not stand in the way of science. Key dates for this research topic are as follows: 1. Abstract submission deadline – 1st May 2017 2. Manuscript submission deadline – 1st July 2017 We very much hope to include your valuable work in this area within this research topic to help make it a key reference and a new resource for neuromodulation research. Yours in Neuroscience, Srikanth Ramaswamy Henry Markram Mriganka Sur Anita Disney Menahem Segal Michael Hasselmo Seung-Hee Lee Alexander Thiele Amy Arnsten