14 Questions
What is the primary focus of studying cognitive processes?
Understanding cognitive processes
What is the purpose of gradients in MRI?
To reconstruct the signal space
What is the term often used to refer to hydrogen atoms in MRI scanners?
Protons or spins
What happens when the frequency of the RF pulse matches the precession frequency of the protons?
The protons absorb energy from the RF pulse
What happens to the alignment of protons in a strong externally applied magnetic field?
They align parallel or anti-parallel to the magnetic field
What is the result of measuring signals during the relaxation phase?
Different signals are emitted from photons in different tissues
What is the purpose of functional MRI in psychology?
To study brain structure and function
What is the purpose of using T1, T2, and proton density in MRI?
To create differently weighted images of the brain
What is the term for the time constant indicating how long the transversal decay takes?
T2 decay
What is the purpose of the radio frequency pulse in MRI?
To excite protons
What is the first effect of the RF pulse on protons?
They start precessing in a synchronized manner
What is the term for the process of protons 'precessing' about an axis?
Precession
What is the term for the process of protons returning to their original state?
T1 recovery
What is the term for the frequency at which protons absorb energy from the RF pulse?
Resonance frequency
Study Notes
Magnetic Resonance Imaging (MRI)
- Protons in a magnetic field are aligned parallel or anti-parallel to the magnetic field (B0)
- The frequency of the radio frequency (RF) pulse must match the precession frequency of the protons to affect them
- Relaxation occurs in two stages: T1 recovery and T2 decay
- Gradients are used to reconstruct the signal space and determine the location of the signal in the brain
- MRI studies have various parameters that can be adjusted to obtain different types of images
Reconstructing Brain Images
- Gradients are used to vary the magnetic field linearly, causing the resonance frequency to vary throughout the brain
- An RF pulse of a specific frequency will only excite one slice of the brain, where the resonance frequency of the protons matches the frequency of the RF pulse
- T2 decay is the transversal magnetization decay, which is an independent process and occurs faster than T1 recovery
- T2 decay is different for different tissues
Neuroimaging in Psychology
- Functional MRI (fMRI) is used to study cognitive processes, not the brain itself
- The brain is studied to gain a better understanding of cognitive processes, as it "computes" these processes
- Neuroimaging methods, including fMRI, are used to understand the neural basis of cognition
Nuclear Magnetic Resonance (NMR)
- NMR refers to the atomic nucleus, which contains protons and neutrons
- More than 70% of the human brain consists of water, which contains hydrogen atoms (H+ protons)
- These protons can be thought of as small bar magnets, precessing like a spinning top about an axis
This quiz covers the basics of Magnetic Resonance Imaging (MRI) and its application in neuroimaging, specifically in the field of psychology. Topics include proton behavior in magnetic fields, radio frequency pulses, and relaxation processes.
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