Memory The Brain THE IB SYLLABUS SAYS Explain

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 Wearing. Oliver 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