Validity of Brain Scanning Images to Study Human Behaviour

04 Apr 2018

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The study of psychological phenomenon has shifted to focus more on brain activity. Critically evaluate the validity of using brain scanning images to study human behaviour

Behavioural neuroscience is a term primarily developed in the early twentieth century and refers to the brain processes and physiological functions that produce human behaviour (Robinson et al, 2005). Pioneers of physiological psychology such as Karl Lashley (1950) surgically produced brain lesions in rats to observe learning and memory alterations, which resulted in many other psychologists mapping the parts of the brain involved, and relating it to human behaviour. This human behaviour, defined as the actions and responses humans portray (Holt et al, 2012), is extensively observed in human brain activity today, and can be monitored using brain scanning images. Some scanning images work by monitoring the electrical conduction of axons to different regions of the brain, glucose and oxygen levels in the brain and blood flow, whilst others visualize the brain structure using tissue density, and all can be used to pinpoint specific behavioural responses (Jezzard, Matthews & Smith, 2001). These imaging techniques present processes that cannot be witnessed by the human eye and can distinguish what parts of the brain are at their most active during different stimulations (bremner, 2005). The increase of brain scanning images makes it one of the most popularly used neuropsychological tools in the field of biological psychology, and has also enthused the creation and promotion of new areas of psychology such as cognitive neuroscience. Yet there is still debate as to how successful brain scanning images are at locating and determining different human behaviours. This essay will depict different types of brain scanning images, their uses in relation to human behaviour, debate how successful or unsuccessful these uses are and hopefully establish a direction to the future of these neuropsychological tools.

The brain is a very complex and active organ, using around 25% of the human body oxygen and 70% of its obtained glucose (Simon, 2007). Due to this complexity and high metabolic rate neuropsychologists want to establish why the brain uses so much energy and where it is consumed during different behavioural events. Originally, single-cell recordings were the most popularly used type of brain scanning images, pinpointing specific neuronal networks used when processing stimuli in relation to behaviour (Holt et al, 2012). For example Electroencephalograph (EEG) can help distinguish whether an ADHD sufferer has an inattentive or hyperactive subtype by monitoring different brain wavelengths (Pedersen, 2013). Clark, Barry, McCarthy and Selikowitz (1998) monitored children in various settings. They were aged 8-12 years and suffered with ADHD. Using EEG measures, the researchers found that the children had substantially higher levels of theta waves compared to the control group. In addition, the children with an inattentive type of ADHD brain waves were closer related to the control group then that of the hyperactive subtype. This demonstrates how EEG measures are a successful non-invasive brain scanning technique, that can be used in many environments and reveals how simple brain scanning images can be used to determine different human behaviours. However EEG measures can be somewhat non-specific and need complex data analysis to help decipher the readings. Furthermore, establishing the amount of brain states an EEG reading can identify would increase the techniques validity (Schlögl, Slater & Pfurtscheller, 2002). SOMETHING TO LINK

Static imaging techniques such as Computed tomography (CT) or Computerized axial tomography (CAT) are used to present a visual structure of the brain and can be useful in detecting deterioration or injury of the brain (Demitri, 2007). They work by using X-ray technology to take pictures of sections of the brain, layering the brains interior from multiple angles. They are 100 times more accurate than normal X-rays and can be used on other bodily organs (CT scan, 2013). This non-invasive method can be used to identify brain abnormalities in abnormal human behaviour such as schizophrenia and bipolar disorder. Pearlson, Garbacz, Moberg, Ahn, and Depaulo (1985) used CAT scans in order to establish a significant lateral ventricular enlargement in patients with schizophrenia or bipolar disorder compared to a control group. Additionally, Bigler, Hubler, Cullum, and Turkheimer (1985) used CAT scans to observe changes in the brain structure of those patients with alzheimers disease and those without. Results portrayed an intellectual decline and memory impairment for Alzheimer disease sufferers. Using these kinds of static brain imaging techniques can help establish a physical determent for human behaviour in relation to brain activity and can also give clinical validity to the technique because it is used not only on the brain but also on other organs (Quiroz et al, 2005). Wedding and Gudeman (1980) even suggest that CT scanning will be an ‘invaluable’ tool in the mapping of the functionality of the brain. However there are disadvantages with using static brain imaging, such as the cost of procedure, the risk of radiation exposure and the relatively poor detail the scan produces (Gould, Cummings, Rabuzzi, Reed & Chung, 1977). In terms of identifying human behaviour, static brain images can only give a physical view of brain abnormalities so it is not always clear what is actually responsible for behaviour.

Instead, dynamic brain scanning images can be used to investigate what is going on internally in the brain when humans experience behaviour. Positron-emission tomography (PET) scans use invasive techniques to measure brain activity such as metabolism, blood flow and neurotransmitter activity (Holt et al, 2012). A radioactive component is inserted into the blood and due to the decaying nature of this component; it is possible to use a detector to observe where the brain is using the most energy (Brain scanning images, 2014). For example Mayberg et al (1999) used PET scans to monitor stimulated feelings of sadness in depressed patients compared to recovered patients. They found that one specific area of the brain had increased blood flow in depressed patients compared to another area that had increased blood flow with the recovered patients. They go on to suggest these types of findings are significant for the use of medical treatments for such disorders, because the PET scan could identify a specific brain region ‘responsible’ for the sadness felt in depression. Furthermore, Jones (2010) describes the work carried out by Dr Ned.H Kalin using PET scans on Anxious Temperament (AT) rhesus monkeys. The central nucleus region of the amygdala portrayed increased blood flow, suggesting an increase in emotion and fear of these types of monkeys. PET scans can be very useful in identifying whereabouts in the brain the most energy is being used when displaying certain behaviours. However, Lubezky et al (2007) also found that PET scanning can have interference when used on patients also having treatment for chemotherapy, which suggests PET scans are not always a successful tool in clinical research. This type of scanning can be very time consuming and the resolution of the brain structure is not as high compared to other brain scanning techniques, which means the functional information retrieved from these scans cannot always be accessed (Positron Emission Tomography, 2013). This means establishing a cause for human behaviour is more difficult and not as concise, so PET scans may not be the most successful choice when researching human behaviour.

Magnetic resonance imaging (MRI) is used to create clear detailed pictures of the brain structure, a lot like CT and CAT scans. Sometimes a dye is injected into the vein to help contrast the picture and images are around 1/10 the size of a CT scan (Rosen, 2007). However, in recent years MRI advancing has resulted in Functional Magnetic Resonance Imaging (fMRI) that can produce dynamic pictures of blood flow in the brain instantly (Holt et al, 2014). This has made a huge impact in the neuropsychological field of establishing what parts of the brain react to different behaviours as it has allowed researchers to present stimuli and observe the results from the stimuli within seconds of it occurring (Jezzard, Matthews & Smith, 2001). A wealth of research has been carried out to investigate this, for example Eisenberger, Lieberman and Williams (2003) used fMRI scans to investigate whether participants reacted to psychological pain in the same way as physical pain. Using a social exclusion task they found a significant relationship between parts of the brain activated during physical pain, in relation to emotional pain. Mastena, Morellib and Eisenbergerb (2011) investigated the effects on brain activity of participants feeling empathy towards an excluded victim, and found that participants with more empathetic personality traits had higher levels of activation in metalizing regions and social pain-related regions of their brain. This in turn led them to carry out more pro-social behaviour towards the victim of exclusion. Horn, Dolan, Elliott, Deakin and Woodruff (2003) also explored impulsivity in relation to aggression, suicide and violent behaviour. Using fMRI scans they found that participants who had greater scores on impulsivity scales had higher activation of paralimbic areas in the brain during response inhibition. Participants with lower scores on impulsivity therefore had lower activation levels in this particular part of the brain. It is clear to see how successful fMRI scans can be at determining what parts of the brain are affected by different human behaviours due to the quick and detailed resolution of the scan. They are also non-invasive with the absence of radiation, making this method a more suitable and reusable option for patients (Devlin, 2007). However, in terms of studying human behaviour, there are statistical pitfalls when using fMRI scans, for example inappropriate interpretations and misunderstandings (Hughes, 2014). For example Watson (2008) describes Marco Iacoboni study investigating swing voters. They were shown political words that they didn’t agree with, such as ‘democratic’, and the amygdala was activated, indicating feelings of anxiety and disgust. However other areas of the brain also became stimulated, in association with reward, desire and connectedness, which presents an opposite interaction of what the participants are feeling, which questions the validity of the fMRI scan all together. Nevertheless, fMRI scans are currently being used in more advancing fields than ever before. The reliability of the scans has even been tested to find out whether they should be used in court as evidence of past memories (Harmon-Courage, 2010). On the other hand, many researchers would suggest it would be more beneficial in terms of research in human behaviour to instead focus on the behavioural and social techniques that could be used to understand behaviour, rather than biological observations. For example Watson (1913) described all behaviour as observable, and any unobservable phenomenon was not proper learnt experiences, and so could therefore not be measured. Yet due to the advancing field of brain scanning techniques, new areas such as cognitive neuroscience have become apparent, and use brain scanning images as a forefront for their research. Cabeza and Nyberg (2000) Analysed regional activations across cognitive domains and found that several brain regions, including the cerebellum, are engaged by a variety of cognitive challenges, which again supports the use of brain scanning techniques in new fields to establish and understanding of human behaviour.

Overall, brain scanning techniques are clearly confidently used in human behaviour research. There are many options as to which type of brain scanning technique to use so researchers can choose the method best suited to them, whether it is observing brain structure, or researching the dynamic function of the brain. That is not to say that there are not drawbacks with using brain scanning techniques. There are practical issues like the cost, and with some types of brain scanning techniques, the exposure to radiation that the participant must experience limits the amount of times a scan can be taken. Also, as explained above, it can also be quite difficult to interpret the scanning image itself and researchers cannot be completely confident that a certain part of the brain is responsible for a certain behaviour. However, the valid use of brain scanning images continues to increase, with new areas of neuropsychology producing new research outcomes, and the increased usage of them in clinical fields. Finally, brain scanning techniques in relation to human behaviour can be said to be relatively valid because of the abundance of rich and detailed findings that they gather.

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