BBC Focus - 09.2019

DISCOVERIES

YOUR WORK FOCUSES ON FORGETTING...
The majority of the public, and also many
of my colleagues, think of forgetting
from the perspective of memory failure.
Forgetting is thus considered to be a
glitch of memory. It is a relatively recent
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a fundamental function of the memory
system, something that it needs to function
properly. On one hand there is a system
that constantly makes sure that structures
that have been formed during memory
formation are maintained, and, at the
same time, there’s a process that tries to
eliminate these structures. We now refer
to this process as an ‘active forgetting
mechanism’, a process that brains use to
remove memories with the goal to keep
memory optimally functional.

SO FORGETTING IS A GOOD THING?
I think there is indeed a bliss in forgetting.
Most of what you experience you can
really forget. It improves the adaptive
aspect of the memory system in the sense

that the brain really only retains what is

considered useful for the major tasks at

hand, to improve chances of survival. If,

for example, you experience a situation

that allows for 20 possible reactions based

on a comprehensive and unselective

catalogue of past events, but actually only

two were effective, you have a high chance

of selecting a wrong course of action. But

if the memory system is designed to make

sure you only retain the best responses,

then perhaps you only have to select from

four choices, and the chance of you doing

the right thing is much higher.

HOW DOES THE BRAIN DECIDE WHICH

MEMORIES TO REMEMBER AND WHICH

TO FORGET?

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there is this built-in process of forgetting,

why do we retain some memories? The

thing is, organised forgetting is necessary

because we tend to remember too much.

That’s the basic problem. We proposed

that the brain is a promiscuous coding

device, that it just encodes whatever it can

when things happen, because the brain

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is important and what is not when things

unfold. It is really hard to make that call

because things happen too fast, often they

only happen once, and you cannot readily

make the decision, “let’s keep that for

later because I might need to remember it

in the future”.

The best approach may be to try to

remember as much as possible when

things happen and sort it out later. We

therefore believe certain forms of forgetting

occur predominantly during sleep,

counteracting the effects of unselective,

‘promiscuous’, memory formation. But my

view is that there are many other active

forgetting processes. They operate on

different timescales along the lifetime of

a memory.

IS THERE AN INBUILT HIERARCHY OF

REMEMBERING AND FORGETTING?

There are ways to decide what might be

important in the future and thus should be

kept instead of being erased. For example,

Farfrombeingaaw,the

ability to forget may play

a crucial role in the brain’s

memory system

What if

I could

remember

everything?

Prof Oliver Hardt neuroscientist

“e brain

really only

retains what

is considered

useful for the

major tasks

at hand, to

improve chances

of survival”

Horizons

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