By Marco Wong
黃俊銘
Corporate
espionage , memory
implantation and information extraction straight
from a person’s mind may sound like the familiar
synopsis to
Inception
, but scientists are making
progress toward bringing this treacherous fantasy
to real life.
Implantation of memor ies is not, by any
means, a new idea. In the 1990s, one famous
formal study on memory implantation involved
a par ticipant’s fami l y member s to nar rate
true events that occurred in the participant’s
childhood, but to insert a false event that did
not take place. The false event in each case
was about getting lost in a shopping mall. The
par ticipants were then asked to recall each
event in more detail and to rate how well they
remembered the events. It was found that 5 out
of 24 participants incorrectly recalled the false
memor y as an event that actually occur red
[1]. While not overly exciting, it does show that
memories are malleable even with very little
coercion.
Memo r i e s can be c l a s s i f i ed i n to t wo
categories – explicit and implicit memories.
Explicit memories or ‘declarative memories’
are formed and temporar i l y s tored i n the
hippocampus. These are memories that can
be recalled, such as facts, knowledge and
information about particular experiences. Implicit
memories, on the other hand, are procedural,
referring to skills that are learned. The ability to
swim or to ride a bike are examples of ingrained
impl icit memor ies. Memor y manipulation is
potentially possible for explicit memories, and
has become a pr ime target for research in
neuroscience. This is because, unlike the coercion
technique mentioned in the “Lost in the Mall”
experiment, memories can be tweaked through
knowledge of the hippocampus’ mechanism.
Most of the large, pyramidal neurons in the
hippocampus have been demonst rated to
possess a causal role during navigation. These
neurons are known as place cells and they fire
when an animal enters a specific area of its total
environment. This helps the animal to acquire
information about when it moves into a certain
place [2]. There is also a second type of cell in
the hippocampus; these are small cells known
as granule cells. Granule cells are more active
during the day while pyramidal cells come awake
during sleep [3]. The previously mentioned place
cells are thought to “replay” wake-experiences
during sleep for memory consolidation.
French researchers applied this mechanism
to ‘manipulate’ memories in mice. They allowed
mice to explore an open field environment and
recorded the spike patterns created from place
cells during this exploration. During sleep, these
Memory
Manipulation
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