Memory-A Century of Consolidation
The memory consolidation theory was proposed
nearly a century ago. Although, the research was presented a number of years
ago; it still provides the framework for modern research. There has been
evidence that that new memories strengthen over time and in stages. Evidence
also showed that cerebral trauma showed a loss of memory to potentially provide
an explanation for retrograde amnesia. The theory was ignored for 50 years but
was considered again in 1949 when electroconvulsive shock produced amnesia in
rodents. The research done by Hebb and Gerard indicates that there are at least
two stages of memory thus protein synthesis is required for long-term memory
consolidation. It was also shown that stimulant drugs that were administered
(within minutes or hours) after training enhances memory consolidation.
consolidation theory is still able to guide research today.
3. Most research on memory consolidation indicate that memory has a time window of hours after learning.
However, recent evidence has shown that memory may continue for weeks, months,
or years and that they are stages of learning. The various stages of
consolidation rely on cellular mechanisms and brain systems. Such as, lesions
on the hippocampus impair recently learned information. This means that the
hippocampus does play a role in consolidating and storing. McGaugh’s work shows that memories are not created
immediately in a lengthy, indefinite manner. Instead, immediately after
learning an event, the memory is impressionable. The longer the time is, the
memory becomes more likely to be resistant to external influences and is stored
more “permanently-memory consolidation.”
are certain drugs, experimented with rodents, that after learning an
event, the drugs can influence the retention of the event. Drugs have an
interesting effect on memory consolidation. For example, amphetamine was
administered to human participants before or after learning a world list. The drug
showed that it enhances memory of the words. These results indicate that
adregenic systems activate the amygdala. Studies have also examined how
pictures accompanied by an emotionally arousing story are remembered. Subjects
who were given a placebo before the pictures were shown remembered, but those
given an adrenergic receptor antagonist were not enhanced. Also, PET scans of the amygdala show
that long term memory is related with the degree of amygdala activation during
“original encoding.” Therefore, memory stages are based on a
parallel, independent process. Short-term and long term affiliation are not
serially linked according to studies of synaptic facilitation.
McGaugh found that Emotions can influence long-term memory. People
tend to have stronger memories of events that were long ago if they were
emotionally arousing in nature than events that were neutral in emotion nature.
This can be seen in participants struggled to remember the word list that had
no emotional tinge to it. Epinephrine and Norepinephrine, stress hormones,
mediate effects of emotional arousal on retention. The two stress hormones
activate various brain structures that play a critical role in regulating
memory consolidation. The amydgala, in particular, when activated influences
other brain structures including hippocampus, nucleus accumbens and caudate
nucleus that also process a different aspect of memory. These brain structures
work together to form and store memories. Experiments activate the time dependent process that is involved in
memory formation. The experience initiates the release of stress hormones from
the adrenal medulla. This activates the release of norepinephrine in the
basolateral amygdala. Neuroplasticity is affected by the amygdala.
5. The conclusions of the article is that memory consolidation is in
phases. Memory and neuroplasticity show that new memory consolidation into to
long-term memory is on a time dependent scale. However, short term and
long-term stages are not linked as per the dual-trace hypothesis. Drugs can
block either short-term or long-term memory which means that the memory phases
are based on autonomous stages.
article highlights how the author investigates the neurobiological systems that
are in control of the emotional aspect of consolidating memories. It was found
that certain stimulating drugs can intensify memory in rodents when they were
given shortly after the training period. This indicates that endogenous systems
(activated by arousal) can affect neural process. Other research has found that
the stress hormones produced by the adrenal medulla can initiate learning
experience. Research also indicates that the stress hormones can be activated
by the amygdala. The basolateral nucleus of the amygdala modulates the impact
of drugs and hormones. The amygdala is able to modulate by projections to the
brain region by using various aspects of memory.
The exact nature of memory storage is still unknown. It would be interesting to
explore this question to find out how memories are stored. Also, does the
hippocampus retain older memories? If the hippocampus were to retain memories
for years and then move on to another region, then could there be more to
memory than a simple consolidation theory?