Down memory lane: Let's remember to forget

The biology of remembering has been extensively investigated but the biology of forgetting started getting sufficient research attention only recently. And it says forgetting is not all that bad!

Most of us are dismayed when we are unable to recall the name of an old acquaintance who catches us in a crowd and enquires “do you remember me?” Or, when listening to a quiz programme, the answer is on the tip of the tongue, but cannot be brought to mind.

The marketplace is full of products ranging from hair oils and mattresses to puzzles and apps, that claim to strengthen our memory. However, forgetting is not all that bad, says an article in the journal Neuron. The authors explain that forgetting is as vital for us as remembering and that a balance between the two is essential for us to be able to make intelligent decisions.

THE BIOLOGY OF IT ALL
When we remember something, our brain attains the state in which it was during the original event. (When you first entered your college, the neural activity in your brain had a specific pattern. If you now reflect on that occasion, your brain would re-enter that pattern.)

When we remember something multiple times, new connections are formed between our neurons, or the existing connections are strengthened, making the memory stronger.

Though the biology of remembering has been extensively investigated, the biology of forgetting started getting sufficient research attention only recently.

Interestingly, it has been demonstrated that forgetting too involves some active processes. The neuronal connections in which our memories are stored can get weakened or actively eliminated over time. Besides, new neurons are continuously developing in the hippocampus, the brain structure which plays a vital role in the encoding of memories.

These new neurons compete with the existing ones for connections and at times replace the old connections. The net effect is a change in the existing circuits and overwriting of the memories stored in them, making those memories harder to access.

BENEFITS OF FORGETTING
If there are active biological processes underpinning the phenomenon of forgetting, and the brain is spending precious energy for the same, forgetting should be serving some purpose. The authors of the Neuron article propose two:

First, in a world that is continuously changing, old information quickly becomes redundant and not as important to remember. Forgetting allows us to adapt to new situations by letting go of outdated information. Memories of events that are fleeting or uncommon could mislead us when we are trying to make predictions in new situations. The persistence of a memory would be beneficial only when it maintains those aspects of an experience that are either relatively stable and/or predictive of new experiences.

Also, the persistence of memories beyond the point of relevance could be disadvantageous when we are in the process of learning new information, especially information that conflicts with the previous experiences. If the brain keeps bringing up multiple conflicting memories while we are trying to navigate the vicissitudes of day to day life, it will become extremely difficult for us to make informed decisions.

Second, ‘selective’ forgetting facilitates decision making by allowing us to generalise and extend the learning from past events to new ones. When we forget the irrelevant details of an encounter and remember only its gist, the result is simpler memories which would be more helpful for us in predicting our new experiences.

So, the goal of memory is not to transmit the most accurate information over time, but to make you an intelligent person who can make the best decisions for given circumstances. And one of the tricks memory uses to get this done is to endow you with the ability to forget some information!

The writer is a psychiatrist with St Thomas Hospital, Changanacherry and editor of the Indian Journal of Psychological Medicine.