FENS-Kavli Network of Excellence: Bridging levels and model systems in neuroscience: Challenges and solutions

"But what's the mechanism? And what's the behavioral relevance?" These very common questions reflect that obvious fact that neural systems can be described at multiple levels. They further reflect the fact that many neuroscientists view the achievement of such multilevel descriptions as an important accomplishment. Neuroscientists have achieved a remarkable level of understanding at each different level, yet comprehensive descriptions that bridge across multiple levels remain a substantial challenge in neuroscience. Many of us may take the importance and the considerable difficulty of this endeavour for granted and, therefore, expect that it will be somehow solved in the future as we make more progress. In contrast, I argue here that concerted action is needed to address this outstanding challenge. I discuss the need to bridge different levels and model systems in neuroscience. I briefly review key concepts from philosophy of science that can create a conceptual framework to do so. Finally, I suggest concrete "bottom-up" and "top-down" steps the neuroscience community can take to make progress in this direction. I hope these suggestions will serve an initial basis for further fruitful discussions that will advance us towards achieving this important goal.