Memory, has long been separated into distinct categories- sensory, short and long term; varies theories are proposed to clarify how memories are encoded and stored. Karl Lashley spent his entire life searching for the “engram”, a localized brain region that is responsible for memory storage, where inducing perturbation in this region will disturb memory in all aspects. Of course, there is none and the nature of memory remains a mystery. After 50 years, the theoretical concept of  Routtenberg and his colleague suggest that memory storage does not exist. There are no discrete brain regions that “store” memory, rather metaphorically, memory is the representation of overlapping, concurrent, multiple reactivated network circuits.

To understand the story of memory, first we must understand the nature of memory. How do we remember our own name? the word Edward can be divided into fragments, the semantic pronunciation, the syntaxical associations between each alphabet, the episodic representation of my self-image. I like to term this mixing of fragments as “schema”, a  general strategical categorization of events. An analogy of  this fragment nature can be drawn from mixing chemicals elements, mnemonic atoms, that of all produce a compound we refer to as memory. But what about recall specific details of episodic events? I remember taking an anatomy course in my first year of university, I forgot most of the anatomical structures that I could have recall easily back in two years. From the skeletal system lectures, I can still remember the location of our sphenoid, but I forgot almost everything other than that. So how do I explain this saliency of remembering sphenoid while forgetting everything else?

As forementioned, memories are linked by fragments of events. According to the computational matrix model of memory, these events can be represented by features and contexts. Breaking down the fragments, we have vector a and vector b. The product of these vectors creates a matrix of features in which is used to compare with the probe item. Increasing the events related to the probe will result a positive match, vice versa. One constraint of this model originates from the fact that memory does not simply represented by features. Memory traces can be found in all other aspects. Features of an item are considered as a piece of puzzle of memory. A ship, can be derived into lines, color, shape, size, episodic events, subjective experiences, which can be all summed up to create a central representation of the item – ship. In summary, the traditional views are flawed, there are no dual storage sites of short term versus long term memory.

The fragment nature of memory inspires my research in protein synthesis. Hebb proposed two stage of learning, first a protein synthesis independent stage that last hours and next, a protein dependent stage that thought to last for days, months, years and life time. The essential question here lies in the mechanisms of “where” and “how” memory are being processed. If there are no dual-storage where as memory are in fact presented as distinct events, the “storage site” will be vast, likely the entire brain is interactively responsible for this process. And the “how” question? Three levels must be considered, first is the molecular level where kinases are involved in feedback cycles. Next we have the cellular level where the so-called retrograde factors are contributed to enhance or dampen the physic synapses of neurons. Finally, the network level. Routtenburg proposed the theory of Post-translational modification (PTM) of de novo proteins. According to PTM, proteins that are necessary for consolidation are preexisted between synapses, and this dynamic view of memory suggests Protein synthesis inhibitors (PSI) role in memory retardation is simply a deprivation of “food” that are necessary for long-lasting memory.

PSI prevents learning and consolidation of memory fragments. In another way, protein synthesis is not an instructive mechanism for long-lasting memory, but rather it is responsible for the persistence of long-lasting memory.

The more I dig into my research, the more fascinating I think of God. The brain is unquestionably intelligently engineered, and here we are to understand the mechanisms and process of our brain.

Memorti.