# David Marr's tri-levels of computational neuroscience

• Computational level

• what does the system do (e.g.: what problems does it solve or overcome) and similarly, why does it do these things
• 最適化の評価関数を決める
• Algorithmic/representational level

• how does the system do what it does, specifically, what representations does it use and what processes does it employ to build and manipulate the representations
• 事象をどう表現（数式化、数値化）するか決める
• Implementational/physical level

• how is the system physically realized (in the case of biological vision, what neural structures and neuronal activities implement the visual system)
• 脳のどの部位がどの計算をしているかを決める