IMHO, they could, maybe should, with some promise start with what are likely relatively low level brain tasks say, among the first things a brain does with an input via touch, temperature, sound, sight, movement.

In a computer analogy, pay attention to the processor, main memory, Ethernet connection, PCI bus, etc.

IMHO, for the usual meanings of behavior, e.g., a kitty cat chases a mouse, a kitty cat jumps successfully from a kitchen stool to the kitchen counter top that has the offered food and water, a kitty cat follows its owner from room to room, etc. are at too high a level.

With a computer analogy, such behavior doesn't really directly involve the processor instruction set, the word length in main memory, communications over Ethernet or USB but involves software.

As we know well, given inputs and outputs of some software, even millions of pairs of inputs and outputs, tough to infer the source code or even the programming language used, C++, C, C#, Lisp, Fortran, etc.

Still, we know some things about software, e.g., the programs commonly use Do-While, If-Then-Else, Call-Return, raise exceptional condition. So, there's a microscopically thin chance that the coveted theory of neuro-science could have the coveted theories with testable hypotheses at roughly that level.

For more about behavior, IMHO have to accept real cognition, actually thinking, e.g., considering scenarios and possibilities for responding. We can guess that the work of this cognition will as software in a computer use relevant accumulated data, some usually crude causal models, and some simple deductive logic.

Can the line of attack in the OP address such cognition? Maybe, but here being closely reductionist standing on solid theories of the lower level functioning is likely asking for too much and maybe, for some progress, not necessary. E.g., commonly parts of psychology study cognition while largely ignoring the lower level neuro-science mechanisms.