- Dynamic functional changes associated with cognitive skill learning of an adapted version of the Tower of London task

Studies Using PET Scans

Which Brain Imaging Technique Monitors Active Areas of the Brain by Measuring Blood Flow Using a Mildly Radioactive Substance?

Positron Emission Tomography (PET) scans have several significant drawbacks. They provide images with little detail, cannot precisely identify the timing of neural events, and necessitate exposing the brain to radiation. Due to these limitations, fMRI is often favored as an alternative diagnostic imaging technique.

Limitations of PET Scans

A Positron Emission Tomography (PET) scan creates pictures of the living, active brain by monitoring a tracer. As shown in the image, the scan produces a rough map where different parts of the brain are displayed in different colors to represent active and inactive areas during a given behavior.

Example of a PET Scan

A tracer is a mildly radioactive substance that is either ingested or injected into an individual during a positron emission tomography (PET) scan. Once it enters the bloodstream, its concentration and movement can be tracked by a computer to monitor blood flow and identify active regions within the brain.

Tracer

Although Positron Emission Tomography (PET) scans have largely been replaced by fMRI, hybrid CT/PET technology is still used in certain contexts because it combines the strengths of both techniques. In this approach, Computerized Tomography (CT) contributes clear images of brain structures, while PET shows the brain's activity. This combination allows for better imaging of neurotransmitter receptor activity, opening new avenues for research in areas such as schizophrenia.

Hybrid CT/PET Technology

Functional Magnetic Resonance Imaging (fMRI) offers significant advantages over Positron Emission Tomography (PET) scans. Specifically, fMRI produces images with greater structural detail and provides better temporal accuracy, meaning it can pinpoint the timing of brain activity more precisely than PET scans.

Comparison of fMRI and PET Scans

Positron Emission Tomography (PET) is a technique used to create images of an active, living brain. The procedure involves administering a mildly radioactive substance, known as a tracer, to an individual either orally or via injection. This tracer enters the bloodstream, and its concentration in different brain regions is monitored. Since increased brain activity correlates with higher blood flow, a computer can track the tracer's movement to generate a map that distinguishes between active and inactive brain areas during a specific task.

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- Sociocultural
- Dosing regimens are not representative 
- Effects of long-term administration of drug use are not conclusive                                     
- Positron Emission Tomography (PET)  is not enough evidence
- Experimental designs are limited to establishing cause and effect 
- Physiological evidence overlaps and is not necessarily clinically significant
- Imaging techniques and clinical assessment are not representative
 

Limitations of drug abuse as a brain disease 

- Magnetic resonance imaging (MRI)
- Functional magnetic resonance imagine (fMRI)
- Transcranial magnetic simulation (TMS) 
- Positron emission tomography (PET)
- Computerized tomography (CT)
- Electroencephalography (EEG)

Techniques for Brain Imaging

Brain imaging techniques involving radiation include:

- Computerized tomography (CT) scan
- Positron emission tomography (PET) scan

Brain Imaging Techniques Involving Radiation

Spielman, R. M., Dumper, K., Jenkins, W., Lacombe, A., Lovett, M., Perlmutter, M., & OpenStax College,. (2017). Psychology.

Psychology by Rosie M. Spielman

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

This outlook is directly related to the implementation of expensive and unsuccessful drug policies as it focuses solely on neural mechanisms as opposed to behavioral and psychosocial factors.

Sociocultural limitations of BDMA


Since animal models are not necessarily representative of human tendencies with regard to drug consumption, conclusions about neurotoxicity can lack validity. For instance, it is hard to determine the neurotoxicity of a drug in an animal model as the regimens followed in dose increase are not the same as in human use. This dose increase leads then to tolerance, which can be neuroprotective.

Dosing regiment limitations of BDMA

There is an ethical limitation in how researchers can evaluate the long-term effects of a drug in a human sample. 

Long-term effects of drug use as a limitation of BDMA

Positron Emission Tomography (PET)

In studies that suggest that there are different cognitive results as well as physiological ones, it is not possible to determine that the differences between control and experimental drugs are the result of one drug and one drug only, or a result of the preexisting characteristics of the subjects. 

Experimental design of cross-sectional studies can be confounded in BDMA

Decreased activity of the striatum, resulting in less dopaminergic activity does not necessarily equate to a clinical implication. Physiological differences can be presented for a variety of reasons and do not necessarily correspond to illness. Furthermore, the overlap of results between control groups and experimental groups can suggest that despite the decreased activity of the striatum, the dopaminergic differences of drug users (such as methamphetamine users) are not clinically significant. 

Physiological evidence for BDMA is not necessarily valid

Techniques such as fMRI are not representative of BDMA as well as clinical studies. Both of these do not present significant functional changes between addicts and non-addicts.

Imaging techniques and  clinical studies are not representative of BDMA

PET scans can be inconclusive as it is hard to determine that the changes in dopamine transportation and the receptiveness of dopamine neurons are not only pathological but that the different results of control groups and the group that uses a drug are due to addiction. For instance, although one can state that the differences between groups are due to neuronal death, one cannot rule out them being a product of downregulation.   

PET scan limitations as an evidence source of BDMA

Magnetic Resonance Imaging (MRI) is a technique that creates images of brain structures. During an MRI, the individual is placed in a machine that produces a powerful magnetic field, causing the hydrogen atoms within the body's cells to align. When this field is switched off, the atoms return to their original state, emitting electromagnetic signals in the process. A computer analyzes these signals, which differ based on tissue density, to construct a detailed image of the brain. This method is commonly used to identify abnormalities such as tumors and injuries.

Magnetic Resonance Imaging (MRI)

Functional Magnetic Resonance Imaging (fMRI) operates on the same principles as MRI but focuses on revealing changes in brain activity over time. It achieves this by tracking variations in blood flow and oxygen levels, as increased neural activity in a brain region requires more oxygenated blood. This allows researchers to map which parts of the brain are active during specific cognitive processes.

Functional Magnetic Resonance Imaging (fMRI)

A Computerized Tomography (CT) scan generates a comprehensive image of a specific section of the body, such as the brain, by combining multiple x-ray measurements. The underlying principle is that x-rays are absorbed at different rates by tissues of varying densities. A computer processes these differences to construct a detailed cross-sectional image, which is frequently used to detect abnormalities like tumors or significant brain atrophy.

Computerized Tomography (CT)

PET:
-Dynamic functional changes associated with cognitive skill learning of an adapted version of the Tower of London task

References for Studies Using Brain Imaging

Not necessarily an imaging technique, but it is used to uncover which parts of the brain are used in different tasks. It does this by disrupting the functioning of a particular area of the brain by creating a pulsating magnetic field using a stimulating coil over that portion of the brain.

Transcranial Magnetic Stimulation (TMS)

Electroencephalography (EEG) is a technique used to obtain a measure of the brain's overall electrical activity. It involves placing an array of electrodes on a person's scalp to record brainwaves. The resulting data provides high-precision information, accurate to the millisecond, about the frequency and amplitude of these waves, making it ideal for applications like sleep studies where precise spatial information is not required.

Electroencephalography (EEG)

The image presents a side-by-side comparison of three distinct brain imaging techniques. From left to right, they are: a Positron Emission Tomography (PET) scan, which uses a color map to visualize metabolic activity; a Computerized Tomography (CT) scan, which displays anatomical structures like bone and soft tissue in grayscale; and a Functional Magnetic Resonance Imaging (fMRI) scan, which overlays areas of brain activity, shown in orange, onto a detailed structural image.

Visual Comparison of PET, CT, and fMRI Scans

Due to their high level of detail, both MRI and fMRI are valuable tools in psychological research. They are frequently used to compare the brains of healthy individuals with those of individuals diagnosed with psychological disorders. This comparative approach helps researchers identify specific structural and functional differences that may be associated with these conditions.

Using MRI and fMRI to Study Psychological Disorders

A cognitive neuroscientist is designing an experiment to determine the exact moment, down to the millisecond, that the brain's auditory cortex responds to a sudden, brief sound. Which of the following brain imaging techniques would be the most suitable for this specific research goal?

A hospital is considering two different patient cases for a brain scan. Case 1 involves a 70-year-old patient who has suddenly lost the ability to speak, and doctors suspect a major stroke or a fast-growing tumor. Case 2 involves a healthy 25-year-old athlete who wants a scan for 'peace of mind' before a major competition, despite having no symptoms. Considering that some brain imaging techniques involve exposing the patient to radiation, which case presents a more ethically and medically sound justification for using such a technique? Defend your choice.

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