There is a lot of study going on about the brain, not limitedt to but including the human. Much is modelled, measured published and discussed, in anatomy, psychology, behavioural science, anthropology, archeology, … too much to count them all.
"Intelligence" can not be defined and has a different meaning for different people. The term also has seen some inflation lately, with companies working on "intelligent" machines. It can mean an automatic windshield wiper (they drive me nuts !), a toothbrush, a chess program, a self-driving car, an automated manufacturing process, whatever. Interestingly, nobody calls for example a mostly autonomous spaceprobe on Mars or around Jupiter "intelligent", though it's software probably does more things automagically than a car or single manufacturing process.
Human “intelligence”, which only is a gradual step from that of other species, is generally understood as the ability for planned actions, cognitive processes, abstract thinking, problem solving (these can be identified by paleo-anthropology and archeology), and additionally softer factors that need more direct observation like learning, language, comprehension and the ability to reason.
I am not sure how much and which part of these actually apply to machines yet without bending the definition in one's favour. Maybe there are publications or texts from those companies, describing what they mean with “intelligent” ? Would be interesting.
Anyway, don't waste too much energy on that. Your immune system might need it soon ;-)