Every
time we retrieve something from our memory it can be changed, rewritten with
new info and re-consolidated in the brain as a new, up-dated memory. There are
specific time windows of this process that could be implemented into the
extinction procedures used for the therapy of phobia and addiction.
The traditional view in psychology and also in
neuroscience is a module-oriented approach: the amygdala relates to emotions,
the hippocampus to memory, and the visual cortex to perception. Subsequently,
the brain has been regarded as a “Swiss penknife”, each anatomical part being a
specialized tool for a certain function. And these functions are ascertained by
the psychology as “psychological processes” or “mental faculties”. Psychology textbooks
are organized into chapters according to
these taxonomies – one chapter for emotions, one for perception, and one for
memory. But what if this paradigm is wrong? Based on the acquired data in neuroscience
various authors have implied that the mental faculties approach should be
altered, pointing out the inaccuracy of this module-oriented organization of
the brain.
From the very beginning, psychology and
cognitive sciences in general, have investigated memory, dividing it into
various subcomponents: sensory, short and long term, procedural and
declarative, implicit and explicit, episodic and semantic. All these paradigms
are based on the same definition of memory: the ability to encode, store and
recall information. One fundamental aspect in this definition is that
information is initially stored and subsequently revealed, in the same way a
“refrigerator” assumes that a certain temperature prevents food from going bad.
Nonetheless, experimental data has revealed that the ability to recall
information is not independent from what we traditionally call “perception”, “imagination”
or “attention”, but rather shares an intimate relation with them. The “perceptual-mnemonic” theory of the brain implies that
it may not be constructive to make a distinction between “perception” and
“memory” as mental functions, as they may seem to be from introspection.
Instead, they should be regarded as different manifestations of a common neural
substrate. There is a dynamic interaction between “perception” and “retrieval”.
Subsequently, retrieval of information is similar to perception because it
involves the identification and understanding of current stimuli according to
past experiences. Some argue that we cannot see something if it does not resemble
information from memory. An anecdotic example supporting this contention is the
story of the native Americans that could not see the Spanish ships anchored
onshore because they did not know anything about ships.
Experimental studies have
shown that is possible to rewrite an old memory with new info, but first you
have to be exposed to the context where that old memory was initially created. Actually
this is happening when people who were witess to an accident or murder are
exposed to information about that incident covered by the media, during the
time interval they wait to testify in Court. Their original memories become
automatically compromised by these new info. This re-exposure trigger a special
labile state in the brain and memory updating is made only when the brain
enters in this labile state and the new info is presented particulary in this
state. It is fascinating ! It’s like a magic key from the Indiana Jones
movies. Hence memory retrieval leads to new memories formation on the
foundation of the stored and reactivated previous experience. Actually the
reality is even more dramatic, being impossible to create new memories without
reactivating past memories. Old memories act like an atractor which capture
info from the same category with them and fix it like a superglue. Even more
fascinating, studies revealed that there are specific time windows when it
comes to change an existing memory. Most of this sort of studies were made for treating phobia and addiction.
In order to overcome a phobia or an addiction, the brain has to re-learn rather
than to erase the undesirable aversive or appetitive memories. This re-learning
is called extinction and consist in the association of the context previously
associated with the drugs of abuse or the unpleasant stimulus, with lack of
drugs respectively with safeness. But in order to be effective, this extinction
technique must obeys some specific rules. Hence, performing a spatial or
contextual learning task 1 or 2 hours before the extinction training facilitates
the effect of training. But not if the exposure was 3 hours before. Why ?
Because this sort of learning produces proteins in the neurons and this
proteins are captured by the synapses and used to consolidate the new memory
created during the extinction training. The process is named tag-and-capture.
Furthermore, the extinction is effective only if procedes between 10
minutes and maximum 2 hours after the exposure to the traumatic context
respectively the reactivation of the traumatic memory. Note the labile state of
the brain induced by remembering/recognition, mentioned above. This is the time
interval it stays labile and can incorporate new info into the existing one.
Fructose or glucose consumption 30 minutes after the exposure/reactivation also
helps. It is important to say that 2 hours after exposure/reactivation, the
time window for the reconsolidation of the new memory is closing, and the
behavioral effect could be noticed only after 2 days when the reconsolidation
process is finished. This procedure could be resumed several times if is
necesary, but the results obtained are garanteed at least 180 days. As you can
see it’s a kind of engineering.
I conclude that knowing the real functional organization
of the brain is a must if we want to explain the mind but especially if we want
to positively impact its performance such as improving learning and
re-learning.
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