Transcript Emotional Memories

Memory & The Brain
THE IB SYLLABUS SAYS: Explain
how biological factors may affect one
cognitive process (i.e. The influence of
biological factors on memory)
Memory & the Brain
• Memory is the job of the brain
• Science is continually exploring the way memory is
organized in the brain
• But there are still many mysteries about the biological
correlates of memory.
• Cognitive psychologists and neuroscientists work
together to find out about the brain structures involved
in memory
• Eric Kendel is a neuroscientist who won the Nobel
Prize in 2000.
• He studies learning and memory at a cellular level in
the sea snail aplysia, a very simple organism.
• He found that STM as well as LTM result in synaptic
changes in the neural networks of these sea snails
• The snails memory is located in the synapses, and he
observed that changes in these synapses are
important in memory formation.
• Kendel also studied memory functioning in relation to
synaptic changes in the brain structure called the
hippocampus
Some biological factors in memory
• It is not yet possible to have a full picture of the
complexity of the biological foundations of
memory, but brain research has provided some
major insights into the nature of memory.
• Kandel’s (2000) research with snails shows that
learning, means formation of a memory – that is
growing new connections or strengthening
existing connections
• Researchers have used animals to study how areas of
the brain are related to memory.
• Typically, animals learn to perform a specific task, for
example running through a maze – and a memory is
formed.
• To find out what areas of the brain are involved in
such a task, researchers cut away brain tissue and the
animal has to run through the maze again.
• This procedure, called lesioning, is repeated a
number of times until the animal can no longer
perform the task – allowing researchers to connect
structure with function (Lashley did this type of
research)
• Obviously, scientists cannot to this to humans,
so researches study people who already have
brain damage
• Such research suggests that STM and LTM are
distinct separate stores of memory (supporting
the MSM)
• They also suggest that LTM must consist of
several stores of memory.
• Damage to different parts of the brain affects
factual knowledge, or knowledge for example of
how to drive a car
The structures of long term memory:
Long term Memory
Explicit Memories
Semantic Memories Episodic Memories
(memories of facts)
(Memories of events)
WHAT
WHEN
Implicit Memories
Procedural
Memories
(memory of how
we
do things)
HOW
Emotional
Memories
(memory of
emotional
states)
HOW
The structure of LTM
• At the first level, LTM is divided into two systems – the
first is explicit, this consists of fact based information
that can be consciously retrieved. This type of memory
focuses on ‘knowing what’
• Explicit memory is divided into two subsystems – the
first is semantic memory, which is a memory for
general knowledge - e.g. Mick Jagger is a signer in the
Rolling Stones
• Episodic memory is the memory of personal
experiences and events – e.g. I saw Mick Jagger last
year in New York.
• The Second unit of LTM is implicit memory,
which contains memories which we are not
consciously aware of.
• Implicit memory contains memories we are not
consciously aware of, one of these is
procedural memory, which is the non
conscious memory for skills, habits and actions
– “knowing how”.
• Implicit memory also includes emotional
memory, which is not fully understood.
• It seems that emotional memories are formed
via the limbic system and they may persist even
when brain damage has destroyed other
memories.
• Researchers such as Kendel have point out the
very important role of the hippocampus in the
formation of explicit memories
• Case studies of people with hippocampal
damage have shown that they can no longer
form new explicit memories, but apparently they
can form new implicit memories
• There is evidence that the amygdala plays a
role in the storage of implicit emotional
memories, perhaps because emotions are used
evaluate experience.
• Le Doux found that certain memories based on
emotional events are remembered better.
• This may be why people suffering from PTSD
(Post Traumatic Stress Disorder) have
problems forgetting, because emotional
memories are quite difficult to get rid of.
• Researchers are beginning to find out how the
brain regulates emotional expressions, and they
have observed that when part of the prefrontal
cortex is damaged, emotional memory is very
hard to eliminate, and it is difficult to control
emotional outbursts.
Some definitions….
•
•
Amnesia can be defined as the ‘inability to learn new
information or retrieve information that has already
been stored in memory.’
Neuroscientists distinguish between two key types of
amnesia
1. Anterograde amnesia is the failure to store
memories after a trauma
2. Retrograde amnesia is the failure to recall
memories that have been stored before the trauma.
• Amnesia can be caused by brain injury or infection.
In the case of prolonged misuse of alcohol, a special
sort of amnesia called Korsakoff’s syndrome may
result.
The Case of Clive Wearing: How brain damage
affects memory processing
• Can you imagine what it would be like if you were
caught in the present and unable to remember
anything from your past or to learn anything new?
• What if you were lost in time, with no sense of the
past or future?
• This is exactly what happed to Clive WearingOliver Sacks (1997) documented his case (see
article)
• Clive Wearing suffers from the most extensive amnesia ever
seen.
• He suffers from both anterograde and retrograde amnesia.
• The transcript of his diary gives a heartbreaking insight into
what its like to lose ones memory.
• MRI scanning of Clive Wearing’s brain shows damage to the
hippocampus and some of the frontal regions.
• This indicates that retrograde amnesia could be explained as
‘trauma that can disrupt the consolidation of memory’.
• The case of Clive Wearing offers insight into the biological
foundation of different memory systems. Wearing’s episodic
memory and some semantic memory is lost. He cannot transfer
new information to long term memory either.
• Clive Wearing can still play the piano and conduct the
music he knew before his illness. These skills are part
of his implicit memory.
• The fact that he can do this is evidence of a
distributed memory system, since implicit memory is
linked to a brain structure other than the hippocampus.
• His emotional memory is also intact, which is clearly
demonstrated in the affection he constantly shows for
his wife
• Normally, we do not know the identity of most
participants in case studies. Researchers are obliged
to keep personal information confidential. However, in
the case of Clive Wearing is different because his wife
has decided to come forward with his story.
The Case of HM: How brain damage affects
memory processing
• One of the most famous case studies of amnesia in the history of
psychology is HM, who was first studied by Milner and Scoville
(1957). Over the years, many scientific studies have been conducted
on HM and his identity has not been revealed. As a result of a head
injury that HM sustained when he was 9 years old, he suffered from
epileptic seizures.
• Since there was no drug treatment for his severe epilepsy at the time,
the doctors decided to perform surgery to stop the seizures. They
removed tissue from the temporal lobe, including the hippocampus.
Following the operation, HM could recall information acquired in early
life, but was unable to form new memories.
• HM suffers mainly from anterograde amnesia and, just like Clive
Wearing, he is unable to remember the faces of people he meets. He
can carry on a normal conversation, but he does not recognize
people who visit him regularly. He can read and reread the same
magazines without knowing that he has already seen them.
• It was a breakthrough in understanding the damage to
HM’s brain when researchers could use the MRI
scanner in 1997. HM had been studied for 44 years
before he was put into the scanner.
• Then it became clear exactly which areas were affected
by the operation and that the damage was not as
extensive as estimated by Scoville.
• The damage was pervasive, however, and included the
hippocampus, the amygdala, and other areas close to
the hippocampus.
• With the scanners, the researchers have a much better
chance of testing which areas of the brain are related to
which areas of memory and skill learning—something
they could only speculate about beforehand.
Ethics in case study research
• HM and Clive Wearing are famous case studies in
cognitive psychology. HM has been studies
extensively with all kinds of tests, ever since his
operation in 1953. He has even donated his brain to
science when he dies. We do not know his identity.
Clive Wearings identity is known to us due to his wife's
book.
1) discuss why participants in case studies are normally
anonymous
2) discuss the ethical considerations in studying an
individual with an interesting disorders or brain
damage, such as HM and Clive Wearing
Explain how biological factors may affect one cognitive process
Serotonin & memory
• The neurotransmitter Serotonin also plays an
important role in memory.
• Brain imaging technology allows us to "see" the
connections between depression and memory.
• Antikainen et al. (2001) found that brain-cell activity
in the frontal lobes is often reduced in depressed
people.
• Part of the explanation for this may involve a brain
chemical serotonin.
• Serotonin regulates blood flow, providing cells with
the fuel they need to operate.
• Blood flow in the brain can be monitored indirectly
with a medical imaging technology called positron
emission tomography (PET).
Serotonin & memory
• Depressed people generally have decreased
levels of serotonin, which may explain the
reduced brain-cell activity.
• Additionally, serotonin is involved in regulating
arousal-the ability feel interested in or
stimulated by normally pleasurable activities.
• The new "second-generation" antidepressant
drugs, selective serotonin reuptake inhibitors
(SSRIs) and monoamine oxidase inhibitors
(MAOIs) boost arousal by increasing the
amount of available serotonin in the brain.
Biology and memory: Questions to check your understanding
1. What are cognitive psychologists and neuroscientists working on to find out
about memory?
2. What has the research shown us so far about memory?
3. Who is Eric Kandel, what did he study, and what did he find?
4. How have researchers used animals to find out about memory? What is the
name of the procedure used?
5. What are the main divisions of LTM?
6. What brain structure are involved in LTM, and what aspect of LTM are these
different structures involved in?
7. What is the difference between antergorade and retrograde amnesia?
8. What does Clive wearing suffer from?
9. What areas of Clive Wearing memory remain intact and which areas are
affected?
10.What does the case of Clive Wearing tell use about the biology of memory?
11.Why was Clive Wearing’s identity not kept anonymous?
12.Explain what the case of HM tells us about biological factors in memory.
13.Discuss why the identity of participants in case studies are normally anonymous
14.Discuss the ethical considerations in studying an individual with an interesting
disorder or brain damage, such as HM and Clive Wearing
15.What is a case study?
16.How can case studies be helpful to neuroscientists?
17.How would neuroscientists determine if a case studies could be generalized to
explain human memory?
18.Explain the relationship between serotonin and memory
SAQ…
• Explain how biological factors
may affect one cognitive
process