In a computer, we have well defined functions blocks that are islands of function. The CPU is over here, the cache memory is close by, the main memory is over there, and the rotating memory is way over there. Once you get used to thinking this way is hard to think of computing working any other way.
The brain does have different functional units but the grouping are very different from what you may be used to if you have worked with traditional stored program computing. The brain weaves the different parts together with the memory and computing units being the same. In the subcortical structures, there are some well-defined functions such as the amygdala. These are still memory and computing mixed. In the cortex, there are about one hundred islands of functional units with the biggest difference being what is connected to a given functional unit; what a given map processes is determined by what it is connected to. The connections may be to some sensory or motor part of the body, or to other maps. These processing units are called by names such as area, map, or region.
I have written two posts that may give you some orientation into how the various memory functions work together in these units.