Exam 3: Methods of Cognitive Neuroscience
Which of the following is an advantage of MEG (magnetoencephalography) over EEG (electroencephalography)?
C
What role does an isotope play in positron emission tomography (PET)? Include a real or hypothetical example.
In positron emission tomography (PET), isotopes play a crucial role as part of the radiotracers used to visualize and measure metabolic processes in the body. These isotopes are special forms of elements that have an unstable nucleus, which emits positrons as it decays to a more stable state. The isotopes used in PET scans are typically positron-emitting radionuclides, such as fluorine-18, carbon-11, nitrogen-13, and oxygen-15.
Here's how the process works:
1. Production of the Isotope: The isotopes used in PET are produced in a cyclotron, which is a type of particle accelerator. They are then attached to biologically active molecules to form a radiotracer. For example, fluorine-18 can be attached to deoxyglucose to create fluorodeoxyglucose (FDG), a compound similar to glucose.
2. Administration of the Radiotracer: The radiotracer is injected into the patient's bloodstream. Because the radiotracer is designed to mimic a natural substance in the body, it travels to the area of interest. For instance, FDG accumulates in cells that use glucose for energy, which includes most cancer cells.
3. Positron Emission: As the isotope decays, it emits positrons. When a positron encounters an electron in the body, they annihilate each other, resulting in the emission of two gamma photons in opposite directions.
4. Detection: The PET scanner detects these gamma photons with a ring of detectors that surround the patient. By capturing many such events, the scanner can map the location of the radiotracer in the body.
5. Image Reconstruction: The data from the detectors are processed by a computer to create cross-sectional images and, if needed, three-dimensional images of the tracer distribution within the body.
6. Analysis: Physicians analyze the PET images to assess the function and metabolism of tissues and organs. Areas with high radiotracer uptake might indicate high metabolic activity, as seen in tumors, inflammation, or infection.
Real Example: A common application of PET is in oncology, where FDG-PET scans are used to detect and monitor cancer. Since cancer cells often have a higher rate of glucose metabolism than normal cells, they accumulate more FDG. This results in brighter spots on the PET images, which can indicate the presence and spread of cancer.
Hypothetical Example: Imagine a new drug designed to target Alzheimer's disease by binding to amyloid plaques in the brain. A PET isotope could be attached to this drug to create a radiotracer. When administered to a patient, the radiotracer would accumulate in areas with amyloid plaques, allowing physicians to visualize the distribution and density of plaques and potentially assess the efficacy of the drug in reducing plaque burden.
In summary, isotopes are essential in PET scans as they provide the means to track biological processes in real-time, offering valuable diagnostic and therapeutic information.
How do computational models contribute to our understanding of cognitive neuroscience? Include an example in your answer.
Computational models play a crucial role in advancing our understanding of cognitive neuroscience by providing a framework for testing and refining theories about how the brain processes information and generates behavior. These models allow researchers to simulate and manipulate complex cognitive processes, providing insight into how different brain regions interact and how neural networks give rise to cognitive functions.
One example of how computational models contribute to cognitive neuroscience is the study of decision-making processes. Computational models have been used to simulate the neural mechanisms underlying decision-making, helping to identify the specific brain regions and neural circuits involved in this complex cognitive process. By manipulating the parameters of these models, researchers can test different hypotheses about how decision-making works at the neural level, leading to a deeper understanding of the underlying cognitive and neural mechanisms.
Overall, computational models provide a powerful tool for integrating behavioral data, neuroimaging findings, and theoretical concepts, ultimately leading to a more comprehensive understanding of the relationship between brain function and cognitive processes in cognitive neuroscience.
Research using ________ models sometimes involves "lesioning" the model to see if it adequately simulates the behavioral deficits observed in neurological patients.
Some progressive neurological disorders can be caused by viruses like the human immunodeficiency virus (HIV) and the herpes simplex virus.
The electrical signal evoked by a class of sensory, motor, or cognitive events, which is observed by averaging multiple EEG traces, is known as a(n)
Describe an experiment you could conduct in order to understand the properties of a particular cell's receptive field.
Functional connectivity is a measure of functional relatedness between different
How do transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) differ? Give a real or hypothetical example of an occasion when one of these methods would be preferable to the other. Explain why.
A patient suffering from a progressive neurological disorder is brought to a neurologist for diagnosis. The neurologist notes that the patient's MRI reveals a great deal of cortical atrophy and suspects that the problem may be Alzheimer's disease. Which of the following symptoms, if also discovered, would confirm this diagnosis?
________ is the science of simulating natural cognitive processes on computers.
The formation of plaques composed of abnormal amyloid protein in the brain is a characteristic symptom of
The term ________ is used to describe the situation in which group 1 is impaired on task X and unimpaired on task Y and group 2 is impaired on task Y and unimpaired on task X. In contrast, the term ________ is used when group 1 is impaired on task X and unimpaired on task Y and group 2 is unimpaired on both tasks X and Y.
The most frequent cause of stroke is occlusion of the normal passage of blood by a foreign substance, such as an embolus.
People are better at identifying a briefly presented letter on a computer screen if the letter is
A blockage of the posterior cerebral arteries that resulted in brain damage would most likely cause a deficit in
Functional magnetic resonance imaging (fMRI) is based on a measurement of
What can you infer about the responsiveness of two neurons in the visual cortex that lie next to each other in V1?
A magnetic resonance imaging (MRI) image is constructed from signals that are generated by
The Sternberg paradigm illustrates that when a set of letters held in short-term memory is tested with a recognition task, the time needed to respond to a probe item is
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