It is not as simple you might suspect.

Let me start with...

It is NOT stored in one location.

It is NOT stored in a fixed group of Neurons.

It is not stored in synaptic terminals.

It is not stored in a specific neural circuit.

It is not stored by enzymatic modification of certain receptor or proteins or genetic facilitation or silencing via methylations.

Then where is it?

It is the electrical waves between areas (but the same memory can be represented by similar electrical waves but using different neurons each time which is "different" than the original neuron that participated in the memory "encoding" and consolidation phase.

So there is NO fixed locus of memory.

Because there is No fixed location needed, the brain's physical size cannot impose the amount the new memory can be formed. Same brain regions participate creating new and unlimited amount of memory.

It is like, how many times you can create waves in a pond or in a river.

The correct answer is: There are no limits (unlike computer hard disk where every disk has predefined read and write function shelf life at the time of manufacturing the hard disk. So they have a limited size.

Now ask yourself.. Is wave part of the water or wave is what water does!

Is a Movie is part of the TV set or what TV set displays!

And Finally, is memory part of the brain or what brain does! If so.. there does the memory come from?

Think.

Reflect.

Find out.

PS:

Even if you are a professional neuroscientist, there is a high chance that you are still not familial with the complex literature on learning and memory. And even you read the vast literature, there is a change that you will not find the true interpretation of the research papers in the formidable labyrinth of Memory. Attached is summary review paper to introduce the complex terrain of Memory. Give a try if you dare.

..

The brain in motion: How ensemble fluidity drives memory-updating and flexibility

DOI: 10.7554/eLife.63550