Cognitive Essay - Fmri vs EEG and LTM -Sample Essay PDF

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Have brain activity measures such as fMRI and EEG given us better understanding of long-term memory than traditional behavioural measures? This paper will discuss the difference between the two biological brain activity measures of Functional Magnetic Resonance Imaging (fMRI) and Electroencephalogram (EEG) and identify their roles within the world of memory. Particularly we will be focusing on how both fMRI and EEG have contributed to long-term memory (LTM) and our understanding of episodic memory within different regions of the brain. Additionally, we will also aim to compare these biological measures to traditional behavioural measures used in the past such as Direct and Indirect tasks. We will also touch on the idea of transfer appropriate processing (TAP) which is also used within LTM processing. Towards the end of the paper, fMRI and EEG will be compared to the traditional behavioural measures and we will divulge into what useful research was found from these methods. We will compare the strengths and limitations of each.

Functional Resonance Imaging, also known as fMRI, is a scan which is used to measure brain activity. It is derived from MRI (Magnetic Resonance Imaging), but fMRI focuses on using the metabolism in the brain, meaning it detects changes in blood oxygen, commonly known as oxygenation (Debener et al., 2006). It is a form of non-invasive imaging of human brain activity (Ritter & Villringer, 2006). For example, if a particular area of the brain is more active, this means that there is an increased blood flow to that region, and therefore there is increased oxygen in that brain region. The fMRI scan is able to detect these cognitive processes and will present a detailed image of the brain and where the activity is happening in an exact moment of time.

On the other hand, Electroencephalogram (EEG) is also a non-invasive measure of brain activity where electrodes are directly put onto the patients scalp to track and a continuous

recording of the electrical brain activity within the brain. The researcher would focus on the number of oscillations presented by the electrodes that are connected to a computer to present the results in the form of a graph. EEG is used widely within the medical community to diagnose brain disorders, epilepsy and other neuronal disorders (Ahmad et al., 2014). Additionally, endogenous states (not impacted by environment or external factor) and event can be measured non-invasively using the EEG scan (Ritter & Villringer, 2006). Over the last decade, researchers have made an effort to integrate the complementary advantages of fMRI and EEG scan and in order to acquire simultaneous data (Ahmad et al., 2014).

Within long term memory, the concept of episodic memory is the idea of focusing on a person’s ability to remember past experiences (Tulving, 2002). It is a neurocognitive system that is different to other memory systems and is defined in terms of materials and tasks. It enables us to understand what role it plays in long term memory and how we use it in our everyday tasks. There is a vast amount of research investigating various methods of training our episodic memory in terms of long-term memory and short-term memory and how information is stored. For example, study by Turchinski et al. (2018) investigated the opportunity to choose enhances long-term episodic memory. The results found that actively influencing unfolding events is beneficial to long-term memory. This could lead to cognitive enhancement, particularly in fields of education. This research was able to investigate how the episodic memory can be used and what can trigger it to function in a certain way. This paper will aim to look at how episodic memory is studied through using both fMRI and EEG scans.

There is a large amount of research which has been conducted in researching long term memory which uses fMRI. Study by Cabeza et al. (2003) looks at attention-related activity

during episodic memory retrieval while using an fMRI scan to do this. As they were looking at episodic retrieval, they were aware that certain regions of the brain would attribute to this process, however their study also focused on using visual attention tasks and if they also activate the same brain regions. They had used the fMRI to perform various scans including anatomical, functioning, image processing and statistical analyses. Their results had found that there was a significant activation in the brain regions for both the episodic retrieval and the visual attention. They had also found that there was activation for both in the medial temporal lobe and overlapping activations in the basal ganglia. They made three main conclusions from this study, but the one that was the most unexpected was the overlap in the medial temporal lobe regions which suggested that they are both involved in processing information within the focus of consciousness (Cabeza et al., 2003). To fully understand the role of the different brain regions in cognitive processes, it is considered essential to compare across the different functions directly. The fMRI scan allowed for this as they were able to cross examine the two and it provided the researchers with clear results and graphs to make their conclusions. In this particular case, the fMRI was useful in giving us detailed information on how amongst both episodic retrieval and visual attention tasks, there are similar parts of brain regions which become active and overlap in activity. Therefore, giving us a further insight into long term memory, specifically episodic.

On the other hand, study by Klimesch (1996) focused on memory processing and the oscillations from an EEG scan. His research focused on the oscillation synchronisation produced for short-term episodic memory compared to long-term semantic memory. The results supported the hypothesis and found that short-term (episodic) memory demands lead to better synchronisation and increase in band power measured by the EEG scan and that the

long-term (semantic) memory demands lead to a task-specific desynchronisation and decrease in band power. From this research, he was able to propose a new memory model which was described on three levels: cognitive, anatomical and neurophysiological. The understanding of these oscillations within possibly the entire brain is essential to a better understanding of cognitive processes, specifically memory. The research states that it would be essential to cognitive psychology and allow to finally describe cognitive processes in terms of oscillations and be essential to future research (Klimesch, 1996). It is evident that the EEG scan is able to produce data which is pivotal in the understanding of cognitive processes and memory.

Additionally, research by Khader & Rösler (2011) explored these oscillations further within long term memory retrieval and the differences in power of the band produced by the EEG. The research looked into detail about the different bands and what information was recorded from the participants, after undergoing a memory task and retrieving information from the long-term memory. The EEG scan was able to establish that difference between the alpha and theta oscillations within long-term memory, specifically retrieval. The evidence that was found can help cognitive and biological psychologists when interpreting data from EEG scans. This study was developed from Kilmesch (1996) research, and therefore it has enabled further investigations and answers to be discovered. There is further research done using EEG for investigating direct and indirect memory tasks by Gruber & Müller (2006).

When focusing on traditional methods of measuring brain activity, we can refer to behavioural methods. This focuses more on how a person is impacted by different tasks and stimuli and whether it alters their behaviours. With regards to long term memory, this can

refer to direct and non-direct tests. A direct task is where participants are asked to report on previous event or experience, this refers to an episodic memory. There can be various ways in which they are tested, for example, they could have either a recognition test, cued recall, free recall or context/source memory test (ref). Indirect tasks on the other hand measure change in behaviour due to experience without reference to the source of information. This can include semantic judgements, free association, skill learning tasks and fragment stimuli identification. An example of these tests being used within long-term memory can be demonstrated by Kellogg et al. (1996) study on the attention in direct and indirect memory tasks with short and long-term probes. Their study used two experiments where students were asked to complete simple addition problems while simultaneously viewing a word or nonword. They were then put through either a direct test of recognition memory or an indirect test or recognition priming. As they were also looking at the degree of attention at encoding, their results found that for both indirect and direct tests are impacted differentially by the degree of attention at encoding. Through this research, we are able to understand to store and remember a stimulus is dependent on the degree of attention given at encoding as well as the retention level. From this, we can depict that through using a direct test such as recognition task, a relationship with how we encode information is made clearer and is essential to the understanding of explicit memory and long-term memory. As a traditional behavioural method, it allows us to establish and understand the basics of encoding and brain activity, particularly long-term memory.

There is also Transfer Appropriate Processing (TAP) where not only passive context is relevant but also active processing as people engaging in this process is important (Morris, Bransford & Franks,1977). This could mean a two-processing task or two types of test. It is still using recognition tests but looks at how specific analysing processes can affect implicit and explicit memory test performance (Graf & Ryan, 1990). These tests are able to analyse

behaviours and understand how different memory processes can be used for different types of tasks. For example, using this method research can be conducted where the encodingretrieval overlap in human episodic memory can be investigated (Rugg et al., 2008). Within this study it is identified that through TAP, the processes supporting encoding and retrieval of episodic memory are interdependent of each other. A successful encoding is only determined by how retrieval is cued and that encoding, and retrieval should not be investigated without each other. This can therefore provide further development into which memory processes are used for different tasks.

Despite fMRI scans and EEG being useful for establishing relationships and conclusions within long-term memory and other neurocognitive fields, they also have limitations which can arise. While the fMRI scan is praised for being a non-invasive method which has whole brain coverage and high spatial resolution, it is also known that it is not capable of measuring a fast temporal varying event (Ahmad et al., 2014). This is due to its hemodynamic response that evolves in seconds rather than in milliseconds (Ahmad et al., 2014). In comparison the EEG scan is able to provide a high temporal resolution neuronal currents within a range of milliseconds (Ritter & Villringer, 2006). With regards to traditional measure methods such as using indirect and direct tasks, despite being able to give an insight into a person’s methodology of storing and recalling a memory and its process, it can be argued that methodological rigor cannot replace theoretical development, particularly when looking at the study of the unconscious (Erdelyi, 1986; Reingold & Merikle, 1988).

In conclusion, it can be stated that both fMRI and EEG scans have been able to establish and find ground-breaking ideologies and evidence for long-term memory and detailed information on our memory processes. The fMRI scan is able to give detailed information

about several brain regions and the activity within them relating to specific tasks associated with episodic memory. Similarly, the EEG scan was able to provide researchers with information in the form of oscillations produced by the electrodes and provide further understanding as to why there were different wave lengths for particular tasks regarding longterm memory. It can be argued that the both the fMRI and EEG are not necessarily considered better forms of measuring brain activity but are very useful combined as they are able to provide in depth detail and investigation as to why the brain processes in the way it does. Behavioural methods are just as useful, but as research has shown have established the foundation of how episodic memory can work when using various tasks, such as recognition....