Is there scientific support for brain modularity?
Yes. Neuroscientists and neurobiologists have collected substantial evidence of brain modularity in different processes, including but not limited to memory (declarative vs. procedural), regulation of cognition (performance monitoring vs. implementation of control) and reward evaluation (immediate vs. future).
Double dissociations have been identified using both imaging techniques and studies of patients with brain lesions. At the same time, neuroscientists argue against a one-to-one mapping between brain systems and functions: each system performs different functions and each function necessitates the intervention of several systems.
Are economic models too simple to explain the intricacies of brain processes?
No. Microeconomic models were initially designed to explain choices in economic environments which, just like human brains, are complex. The purpose of this type of models is to find a logical mapping between the characteristics of the object of study (the causes) and the observed phenomena (the consequences). Rather than trying to explain all events at once, the model breaks the environment into small pieces and focuses on a subset of them. It deliberately ignores characteristics that are orthogonal to the object of study or modify only the magnitude of the effect, simply because these extra elements pollute the analysis.