Mechanisms of Memory

You will have seen a lot of cover on the science of education recently. Certainly that topic has been taking a lot of my time. However the other module I am enrolled in this semester is the ‘biological foundations of memory’.

I’ve been studying today the encoding of memories; specifically the electroencephalogram (EEP) readings for the encoding of memories. In this domain, the encoding of memories can be identified by a simple test. One presents images during a study phase, and then presents those images again, along with some novel ones, and asks participants if they have seen the said images before. By subtracting the brain waves recorded during the encoding phase (discriminated by the results of the test phase) of images subsequently recognised from those forgotten, one can measure the brain activity at given locations that represent memory encoding. Differences are discovered, as you might expect, but there’s more to it than that.

Another comparison, carried out by Yovel and Paller (2004) compared difference waves between familiar items, and recalled items, compared to items forgotten of the respective categories. Familiar items represent semantic memory (of meaning), whereas recalled items represent episodic memory. This is because as items are recalled, the participant remembers memorising them in the test phase. Indeed, as you can see below, there are some unique patterns for each category.

Yovel & Paller (2004)

Yovel & Paller (2004)

As far as our class goes, it is now mine to judge whether this represents a general unspecific mechanism or a number of specialised mechanisms.

Topographically, the recollection brain activity (which indicates episodic memory) completely encompasses the familiarity brain activity. Certainly the components of any episodic memory contain semantic components, so it is entirely logical that the components to process the episodic memories will activate semantic areas.

I don’t see any dissociations, however at the same time, these topographies span the entire brain, which is a bit big for one general mechanism. Based on that, I think the system breaks down into specific components which are actively connected during the episodic encoding experience.

So that is my synthesis. I don’t know what the most groundbreaking research might be saying about these concepts. It is likely that further experiments might be able to break this down and dissociate things further, however our lecturer is an active researcher in the field, so I imagine things are largely up to date. However I am going to leave matters at this conclusion for now.