Discuss the use of brain imaging technologies
HM was later studied using an MRI in 1997 by Corkin. Parts of his temporal lobes and his hippocampus, and related structures, were missing on both sides. By using MRI researchers where therefore able to show these related structures are involved in specific neurotransmitter pathways to do with memory, as well as transferring short term memories to long term. Using MRI scanning technology enabled researchers were to investigate the effects of biological factors on behavior and make these correlations between certain brain areas and memory and other behavior. It was important in finding how the medial temporal region with the hippocampus is not the site of permanent storage alone, seems to just play a role in how memories are organized and then stored elsewhere. The structures seen would not be able to be clearly seen using other technologies such as EEGs or CTs.
Advantages of MRI MRI scans are particularly to show how the blood flows in the brain and can be used to identify problems with blood circulation. They can be used for the early detection of Alzheimer's' disease. They are safe to use since no radioactive material is used. More detailed information about the brain than CAT scans Can be obtained from numerous different angles, whereas CAT scans can only be obtained from a horizontal plane. Provides controlled experimental conditions Non-invasive, unlike PET scans Validity because what is found by the scan is then often found in reality. They are accurate for finding abnormalities in the brain and other parts of the body Replicable as can be repeated with same studies. Scientific method.
Conclusions: · Different part of the brain was used for different Flashbulb · Close personal experience may be critical in engaging neural mechanisms that produce vivid memories characteristic of flashbulb memory Correlational study - not a clear cause and effect Lacks ecological validity, but application in other situations could be useful
Advantages of fMRI It does not use radioactive substances, safe to use It can record activities in all areas of the brain Non invasive Provides both anatomical and functional information, which permits an accurate anatomical identification of the regions of activation in each subject The spatial resolution is quite good, approaching the 1-2 millimeter range
Disadvantages of MRI They are very expensive Movement may affect pictures, uncomfortable for patient too - must follow ethical guidelines They cannot say anything about a cause effect relationship
FMRI Functional magnetic resonance imaging (fMRI) registers changes in blood flow in the active brain (oxygen and glucose consumption in the brain). The researchers can then make a map of areas in the brain related to specific cognitive processes. fMRI scanning is widely used by cognitive neuroscientists and other researchers and its use has increased enormously over the last 10 years. Sharot and Phelps 2007 - Flashbulb Memories Aim: Investigate upon the existence of Flashbulb Memory
Procedure: 24 witnesses of the 9/11 incident were found from different location of Manhattan as subjects. Subjects were placed in an fMRI machine. Subjects were asked to recall the event of 9/11. Subjects were also asked to recall their summer holiday (for control purpose).
Findings: · People closer to where the event happened (where the World Trade Center was) had a more in-depth recall of the event. · When compared to subject's summer holiday, the level of detail given for 9/11 incident was higher. · Parahippocampal Gyrus (responsible for LTM retrieval) was relatively inactive when recalling memories from 9/11 when compared to recalling events from summer holiday. · Amygdala (responsible for processing memory of emotional reaction) was relatively more active when recalling memories from 9/11.
Disadvantages of fMRI The focus is mostly on localized functioning in the brain and does not take into account the distributed nature of processing in neural networks. The results are correlational so it is not possible to establish a cause-effect relationship We do not obtain immediate evidence of brain activity, as blood flow follows neuronal activity in the cortex by almost one second.
In conclusion, brain imaging technologies are very useful in determining the relationship between biological factors and behaviour Useful in different situations. All these methods have their own advantages and disadvantages, primarily involving invasiveness and levels of radioactivity. However, all of these methods contribute to investigating the relationship between biological factors and behaviour.
By using an MRI, Maguire was able to observe the structures in the brain and find a correlation between environmental enrichment on neuroplasticity, a physiological process occurring in the brain, particularly around the hippocampi region which then affects behaviour in terms of memory. Maguire used MRI scans to investigate the structure of the hippocampi, which would not be able to be seen using other technologies such as an EEG or a PET scan.
Milner and Scoville's study in 1957 on patient HM, is another which utilizes MRI scans to investigate a physiological process. HM suffered epileptic seizures after a head injury at age 7. Doctors performed surgery to stop these seizures when he was in his twenties. The tissue from his temporal lobe, and hippocampus was removed in this surgery. After the surgery, HM suffered anterograde amnesia and partial retrograde amnesia. He couldn't transfer new semantic and episodic memories into his long term memory, and he couldn't form new long term procedural memories. He had some capacity for working memory, but would forget immediately.
Brain imaging techniques are used in neuroscience to investigate the relationship between brain structures and behavior, for example after brain damage or to find out which areas of the brain are involved in which cognitive activities. Brain-imaging technology is a promising way to investigate the possible relationship between biological factors and behavior, but so far scanning can merely register structures and activity in the brain. It is not possible to determine a cause-effect relationship at this point. Brain imaging is mainly about mapping brain structures and activity in the brain. Another limitation deals with localization of function. It may be possible to identify brain structures that are active during a task, but since most structures are linked to other structures in networks, it is not possible at this point to say definitely where things happen in the brain.
MRI Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. MRI produces three-dimensional images of brain structures, and is used to detect structural changes in the brain, in cases of brain damage and illness. MRI has been used extensively in monitoring and diagnosing disease. Maguire et al. (2000) is an example of a study which used MRI scans to investigate the relationships between biological factors and behavior.
Aim: Maguire hypothesized that full licensed taxi drivers in London would have a different hippocampi structure in their brains compared to "normal" people. The study was based on the knowledge that London taxi drivers must do a two-year training course where they end up being able to find their way around the city without a map - this is known as "the knowledge". MRI scans were used to scan the structure of their hippocampi, which were compared to already existing MRI scans of healthy males who did not drive taxis. It was a natural quasi experiment in which they looked at the volume of grey matter (VBM) and counted the pixels of each slice (/25) of the brain, from MRI scans.
Results: - Taxi drivers left and right hippocampi had a larger volume compared to the non-taxi drivers. - Some parts of the hippocampi were smaller in the taxi drivers. - VBM showed there was a significant amount of more grey matter in taxi drivers - No difference in overall hippocampal size, but a different shape - Posterior hippocampus larger than anterior in taxi drivers - non taxi drivers were even Conclusions: Maguire concluded that there was probably a redistribution of grey matter in the hippocampi of taxi drivers due to the regular use of the spatial memory skills required to remember roads; the neurons are stronger in areas of the brain which are used most.