Word for how something works

Solution 1:

English loves verbs (it is a verbalizing language), French loves nouns (it is a nominalizing language). Alors:

Ex: Scientists have only partially grasped the physiological ________ of magnetoreception in animals. Ex: The _________ of neural networks in the brain is still poorly understood.

would become:

Ex: Scientists have only partially grasped how the physiology of magnetoreception works in animals.

AND:

Ex: How neural networks work in the brain is still poorly understood.

That's what I would do if I were writing an English text.

[I am a French-to-English translator...if that's any consolation.]