This essay will discuss the different strengths and weaknesses of different neuroimaging techniques that cognitive neuroscientists use to understand different mental processes and different biological bases of behavior . These examples include fMRI (functional magnetic resonance imaging), PET (positron emission tomography), MEG (magnetoencephalography), and TMS (transcranial magnetic stimulation). Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay fMRI is a hemodynamic method that measures the amount of deoxygenated blood in certain parts of the brain (Ward, 2016). The amount of deoxygenated blood emits a BOLD (Blood-Oxygen-Level Dependent) signal and converts into voxels (shape of pixels) that allow us to see a 3D image of the brain and track neural activity (Martin & Carlson, 2019 ). When the amount of neuronal activity increases, the amount of blood flow also increases which causes glucose levels in the brain to rise. This, in turn, causes the blood vessels to dilate; evidently increasing the volume of deoxygenated blood (Heeger & Ress, 2002). A strength of this technique is that it is non-invasive, meaning you don't need to insert anything into the body or brain to monitor neuronal activity. Furthermore, fMRI scans have good spatial resolution: this means that the precision with which we can see where a certain event occurs is good (Pinel & Barnes, 2017). It can also achieve up to 1 millimeter of spatial resolution if the fMRI scan is very high resolution, however the typical BOLD response will have approximately 3 - 6 millimeters of spatial resolution (XUE et al., 2010). Despite the positive aspects of fMRI scanning, it also has its disadvantages such as poor temporal resolution – which implies that the time required to acquire a single image of the brain is slow (Cabeza & Nyberg, 2000). Martin and Carlson (2019) stated that it takes approximately 3 seconds to complete one frame of the brain, which is slower than other techniques, such as MEG scanning. In addition to having poor temporal resolution, fMRI scans show correlation rather than causation since other physiological activities in the body can cause the influx of deoxygenated blood into a certain area of ​​the brain; therefore making it difficult to tell whether the BOLD signal measures what it is intended to measure. Overall, fMRI is a safe, non-invasive way to measure neural activity in the brain with astonishing spatial resolution. Despite poor temporal resolution, fMRI is a popular method for measuring neuronal activity in the brain due to its lack of invasiveness (XUE et al., 2010). Another hemodynamic scanning technique is PET. However, unlike the fMRI scan, the PET scan measures changes in blood flow directly as opposed to the bold signals that measure deoxyhemoglobin (Ward, 2016). PET scans work by inserting a radioactive tracer into the body, usually a form of glucose. For example, F-18-2-fluoro-2-deoxyglucose (FDG) traveling to the brain to release positrons. The positrons proceed to collide with electrons in the brain, releasing gamma rays at 180° to each other, and the activity levels of the areas are shown by the different concentrations (Martin & Carlson, 2019). For example, a higher level of FDG uptake is found in places that may be affected due to different infections (e.g. an autoimmune disease) and therefore FDG concentrations will be higher in those areas. A strong point of this technique is that it has goodspatial resolution – approximately 5 – 6 millimeters. However, one of the main limitations of this scanning technique is that it is invasive as it requires the injection of a tracer into the bloodstream (Martin & Carlson, 2019) . In addition to this, the temporal resolution is poor as it is around 30 seconds (Cabeza & Nyberg, 2000). Furthermore, due to the levels of radioactivity and the invasiveness of this technique, children are not allowed to have this type of scan, which therefore means that we cannot see how the brain develops during childhood with this technique and limits our knowledge about this area (Martin & Carlson, 2019). In conclusion, PET is an invasive technique that hinders our knowledge of how the brain develops during the early stages of childhood. However, despite this, PET scans have astonishing spatial resolution and have helped us in understanding other mental processes such as speech perception, memory, and reading (Martin & Carlson, 2019). A different technique from fMRI and PET scans is TMS which is an electromagnetic technique that, instead of recording the neuronal activity of the brain, stimulates it (Ward, 2016). TMS works by placing a magnetic coil near the head, and inside the magnetic coil there is a variable electric current that creates an electromagnetic field (Kobayashi & Pascual-Leone, 2003; Pashut et al., 2011). The coil's magnetic field causes neurons within the brain to depolarize (more likely to fire an action potential) or hyperpolarize (less likely to fire an action potential) (Kobayashi & Pascual-Leone, 2003). A major advantage of this technique is that it is one of the only ways to measure causality rather than correlation (Walsh & Cowey, 2000). This means that, unlike fMRI or PET scans, the magnetic coil next to the skull directly influences neuronal activity which then induces a change in behavior, for example hand movement (Pashut et al., 2011). Similar to fMRI, this is a non-invasive technique as it is not necessary to inject a tracer into the body (Hallett, 2007; Kobayashi & Pascual-Leone, 2003). A limitation of this technique is that if the magnetic coil increases in temperature, it could potentially harm the patient and/or damage the machine (Wassermann, 1998). However, this problem could be solved by producing a water-cooled battery capable of preventing this problem from occurring (Wassermann, 1998). Although single-pulse TMS is relatively safe, repeated-pulse techniques may induce a seizure in patients who have had a history of seizures (Sack & Linden, 2003; Ward, 2016). Patients who have been diagnosed with epilepsy (or who have a family history of epilepsy) are not allowed to use TMS due to the danger of inducing a possible seizure. Furthermore, patients should be informed before undergoing TMS that it may cause discomfort as it can induce involuntary contractions of the facial muscles, giving them the right to withdraw at any time if the discomfort becomes too extreme (Ward, 2016). In summary, TMS has its dangers, however if participants are informed beforehand and have no history of epilepsy, this technique is effective as it establishes a direct cause and is used to treat several disorders such as depression and anxiety (Walsh & Cowey, 2000). .The final scanning technique in this paper is MEG which measures the brain's electrical activity with a superconducting quantum interference device (SQUID) (Martin & Carlson, 2019). The SQUID device must be immersed in liquid helium but these are sensors that are placed on the headof the patient to measure the magnetic activity of neurons within the brain. After the SQUID has been placed on the skull, the head must be scanned with small magnetic coils to ensure that the person's skull is relative to the SQUID device (Proudfoot et al., 2014). One of the strengths of this technique is that it is a good localization technique since when neuronal activity is stimulated in a certain area by a specific stimulus, SQUID detects the magnetic field and therefore shows the area that has been used (Martin & Martin, 2003 ). Furthermore, MEG is a non-invasive technique as it measures exclusively the magnetic field of the electrical activity of the neurons; therefore it does not require the insertion of a tracer. However during an MEG scan, if there is any head movement, it immediately reduces the quality of the data and therefore the patient must remain extremely still during the scan (Boto et al., 2018). On top of this, MEGs are extremely expensive and, because they must be conducted behind a magnetically protected room, they are extremely difficult to move (Stam, 2010). Overall, MEG is a non-invasive scan that has an amazing localization technique and is safe for participants to use, unlike TMS which has its own dangers of inducing seizures. However, because the SQUID must be immersed in liquid helium and the technique must be performed in a magnetically protected room, MEG is an expensive technique and impossible to move. Please note: this is just an example. Get an article customization now from our expert writers. Get a Custom Essay In summary, all neuroimaging techniques all have their strengths and weaknesses; for example, fMRI, MEG and TMS are all non-invasive techniques while PET scans are invasive as they require the injection of a tracer that enters the body. Hemodynamic techniques have better spatial resolution than temporal resolution, while the opposite could be said for electromagnetic and magnetic techniques. PET, fMRI and MEG also allow us to see a correlation between brain activity and cognitive activity while TMS is one of the few techniques that can be used to establish clear cause and effect. References Boto, E., Holmes, N., Leggett, J., Roberts, G., Shah, V., Meyer, S.S., Muñoz, L.D., Mullinger, K.J., Tierney, T.M., Bestmann, S., Barnes, G.R. , Bowtell, R., & Brookes, M. J. (2018) . Moving magnetoencephalography towards real-world applications with a wearable system. Nature, 555 (7698), 657–661. https://doi.org/10.1038/nature26147Cabeza, R., & Nyberg, L. (2000). Imaging Cognition II: an empirical review of 275 PET and fMRI studies. Journal of Cognitive Neuroscience, 12(1), 1–47. https://doi.org/10.1162/08989290051137585Eysenck, M. W., & Keane, M. T. (2020). Cognitive psychology: A student manual. Taylor & Francis Group. http://ebookcentral.proquest.com/lib/edgehill/detail.action?docID=6130927Hallett, M. (2007). Transcranial magnetic stimulation: a primer. Neuron, 55(2), 187–199. https://doi.org/10.1016/j.neuron.2007.06.026Heeger, D. J., & Ress, D. (2002). What does fMRI tell us about neuronal activity? Nature Reviews Neuroscience, 3(2), 142–151. https://doi.org/10.1038/nrn730Kobayashi, M., & Pascual-Leone, A. (2003). Transcranial magnetic stimulation in neurology. The Lancet Neurology, 2(3), 145–156. https://doi.org/10.1016/S1474-4422(03)00321-1Martin, G. N., & Carlson, N. R. (2019). Psychology (sixth). Pearson. http://edgehill.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwdV3JCsIwEB1cLoIH97 34A0qbpNuxiuJdkeJFkjQ5ePDkxb93prYqQo8hMCQhzPJmeQCcrd3Vn07QwrM80LFVkRQG7U5mAhEpdBc8L ZglZPtyEceUpynVy5Y8gFoSdQb1p1I9IyVRqb2KgCaCyguyMs7QxMd1qKMvQFFZkXa65Vm2 EOMT4uXziJUpdv0oKuY8lWsaTVkK_LEs-w40qNugCzVz70Hro46e_d_FAJz97rQ9rEoR1wJ1, 16(5), 1054–1065..1041.2010.00120