A challenging task for the future will be to bridge the gap in knowledge between development and function. This includes a deeper understanding of how developmental programs align with functional circuit units

and behavior, a problem that can now be tackled from many different angles. This Review demonstrates that a similar logic applies to multiple levels in the hierarchical organization of motor circuits and outlines some of the open questions and opportunities for further experimental investigation. Since motor behavior is the final common output of most nervous system activity and also influences circuits not directly concerned with movement, understanding organizational BKM120 purchase principles of motor circuits will have an impact far beyond the direct control of motor behavior. The broad coverage of topics in this review required a citation strategy mainly focusing on original recent literature described in more detail here. I would like to apologize to authors of the many

additional important original studies for citing Review articles instead. I am grateful to Rui Costa and Ole Kiehn for discussions and comments on the manuscript and to Ole Kiehn for pointing out the term “pseudocommissural” to me. S.A. was supported by an ERC Advanced Grant, the Swiss National Science Foundation, the Kanton Basel-Stadt, EU Framework Program 7, and the Novartis Research Foundation. “
“The human brain comprises Gemcitabine concentration some 100 billion neurons and possesses a computational capacity that far exceeds even the most powerful computers. This impressive degree of cerebral horsepower is not the product of some 1011 automatons working in isolation. Rather, the massive and massively flexible capacity of the human mind is enabled by the ability of these neurons to organize themselves into coherent coalitions, dynamically arranged in precise temporal and spatial patterns. The number of neurons

in the all human brain is dwarfed only by the number of their potential connections: even if only two-way interactions are considered they exceed nearly 100 trillion, if one accepts a count of synapses as proxy. Simply put, what makes a brain a brain is its ability to flexibly create, adapt, and disconnect networks in a manner that permits efficient communication within and between populations of neurons, a feature that we call connectivity. The panoply of cognitive, affective, motivational, and social processes that underpin normative human experience requires precisely choreographed interactions between networked brain regions. Aberrant connectivity patterns are evident across all major mental disorders, suggesting that breakdowns in this interregional choreography lead to diverse forms of psychological dysfunction. The purpose of this review is three-fold. First, we will evaluate current conceptual and methodological approaches to measuring neural connectivity using functional brain imaging.