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Questions and Answers

What type of magnetic material is strongly attracted to magnetic fields and can pose safety risks in MRI?

  • Paramagnetic materials
  • Ferromagnetic materials (correct)
  • Diamagnetic materials
  • Superparamagnetic materials
  • Which property describes a material that is slightly repelled by magnetic fields?

  • Ferromagnetism
  • Diamagnetism (correct)
  • Hexamagnetism
  • Paramagnetism
  • What happens to hemoglobin when it binds oxygen?

  • It undergoes a conformational change (correct)
  • It turns ferromagnetic
  • It remains unaffected
  • It becomes more paramagnetic
  • Which of the following substances act as contrast agents in MRI due to their paramagnetic properties?

    <p>Gadolinium</p> Signup and view all the answers

    What is the primary safety concern regarding ferromagnetic materials in MRI?

    <p>They can be attracted into the magnet causing potential injury</p> Signup and view all the answers

    Which material is known to exhibit both paramagnetic and diamagnetic properties depending on its oxygen saturation?

    <p>Hemoglobin</p> Signup and view all the answers

    Why are MRI systems designed to minimize ferromagnetic materials?

    <p>To ensure patient safety and equipment integrity</p> Signup and view all the answers

    What occurs when biological tissues are subjected to magnetic fields?

    <p>They are weakly diamagnetic</p> Signup and view all the answers

    What property do paramagnetic substances exhibit that makes them attracted to magnetic fields?

    <p>They contain unpaired electrons.</p> Signup and view all the answers

    Which of the following materials is considered a diamagnetic substance?

    <p>Platinum</p> Signup and view all the answers

    How does hemoglobin's binding of oxygen affect its magnetic properties?

    <p>It reduces its paramagnetic characteristics.</p> Signup and view all the answers

    What enhances MRI images when using gadolinium as a contrast agent?

    <p>Altering the relaxation times of nearby protons.</p> Signup and view all the answers

    Which safety feature is NOT associated with MR-compatible EEG cap systems?

    <p>Metal electrode cables</p> Signup and view all the answers

    What is a common characteristic of most biological tissues in relation to magnetism?

    <p>They are weakly diamagnetic.</p> Signup and view all the answers

    Which component is essential for the MR compatibility of EEG caps?

    <p>Shielding against RF interference.</p> Signup and view all the answers

    What happens to deoxyhemoglobin's magnetic properties when it is fully oxygenated?

    <p>It becomes diamagnetic.</p> Signup and view all the answers

    What component is NOT part of a commonly used MR-compatible EEG cap system?

    <p>Ferromagnetic material</p> Signup and view all the answers

    Which property of materials is relevant for ensuring patient safety during MRI?

    <p>Ferromagnetism</p> Signup and view all the answers

    What is the primary safety feature of the MR-compatible EEG cap?

    <p>Plastic electrode holders</p> Signup and view all the answers

    What is the main purpose of RF shielding resistors in EEG caps?

    <p>To prevent RF energy interference</p> Signup and view all the answers

    Which of the following statements about paramagnetic materials is true?

    <p>They improve contrast in MRI images.</p> Signup and view all the answers

    What type of magnetic field is primarily generated by gradient switching in MRI?

    <p>Rapidly changing variable magnetic field</p> Signup and view all the answers

    Which material is considered weakly diamagnetic in the context of MRI?

    <p>Deoxyhemoglobin</p> Signup and view all the answers

    What is the primary purpose of correcting gradient and cardioballistic artifacts?

    <p>To ensure data quality</p> Signup and view all the answers

    Which method involves creating an estimate of the gradient artifact to remove it from noisy data?

    <p>Template methods</p> Signup and view all the answers

    What frequency range is primarily associated with the alpha rhythm identified in EEG recordings?

    <p>8-12 Hz</p> Signup and view all the answers

    When does the alpha rhythm exhibit the highest amplitude?

    <p>When a subject is awake and relaxed with eyes closed</p> Signup and view all the answers

    Which of the following techniques is NOT listed as a main method for correcting gradient artifacts?

    <p>Wavelet transformation</p> Signup and view all the answers

    What is the essential characteristic of the neuronal EEG signal in relation to the gradient artifact?

    <p>It averages out to zero across many TRs.</p> Signup and view all the answers

    What physiological activity is the alpha rhythm potentially an index of?

    <p>Cortical inactivity</p> Signup and view all the answers

    What is the primary cause of an action potential in a neuron?

    <p>Sudden flow of ions in and out of the neuron</p> Signup and view all the answers

    Which of the following is a marker of N2 light sleep in EEG readings?

    <p>Spindles</p> Signup and view all the answers

    How do postsynaptic potentials (PSPs) differ from action potentials?

    <p>PSPs last longer than action potentials</p> Signup and view all the answers

    Which of the following accurately describes a postsynaptic potential?

    <p>It involves changes in membrane potential due to neurotransmitter binding</p> Signup and view all the answers

    What is a significant factor for ensuring compatibility in simultaneous EEG-fMRI procedures?

    <p>Limiting the introduction of ferrous materials</p> Signup and view all the answers

    What is the primary nature of an action potential compared to a postsynaptic potential?

    <p>Action potentials are all-or-nothing events, while PSPs are graded</p> Signup and view all the answers

    Which of the following best describes the duration of a postsynaptic potential?

    <p>It can last for tens to hundreds of milliseconds</p> Signup and view all the answers

    What is a consequence of neurotransmitter binding at synapses?

    <p>It can create a change in the postsynaptic membrane potential</p> Signup and view all the answers

    Which statement is true regarding the changes in membrane potential during an action potential?

    <p>There is a temporary shift from negative to positive voltage</p> Signup and view all the answers

    What does an increased P300 amplitude generally indicate?

    <p>Greater significance of the event</p> Signup and view all the answers

    What do shorter P300 latencies typically suggest about mental performance?

    <p>They indicate superior mental performance</p> Signup and view all the answers

    Which disorder is associated with a decrease in P300 amplitude?

    <p>Schizophrenia</p> Signup and view all the answers

    What effect does caffeine have on P300 amplitude and processing?

    <p>It facilitates quicker mental processing and less attention demand</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the P300 wave in individuals with schizophrenia?

    <p>Increased P300 amplitude</p> Signup and view all the answers

    What does the latency prolongation of P300 suggest about cognitive processes?

    <p>Deficits in attentional or working memory systems</p> Signup and view all the answers

    Which of the following psychiatric disorders has been noted for P300 amplitude reduction during manic psychosis?

    <p>Bipolar disorder</p> Signup and view all the answers

    In terms of P300, what does an increase in the cognitive resources demand imply?

    <p>An increase in P300 amplitude</p> Signup and view all the answers

    Study Notes

    BM402: Engineering in Medicine

    • Course name: BM402: Engineering in Medicine
    • Date: 24th October 2024
    • Location: M 2170 - South Campus

    MRI

    • Functional MRI
    • Applications of MRI and fMRI
    • EEG
    • Applications of EEG
    • Multimodal Imaging

    EEG Basics

    • Electro-encephalo-gram (EEG): Measurement of electrical patterns on the scalp reflecting cortical activity (brainwaves).
    • Electrical: EEG measures electrical potentials from the brain.
    • Electrode: Electrodes are placed on the scalp to measure the electrical potentials.
    • EEG cap: A cap containing electrodes to measure electrical signals from the brain.
    • Amplifier: An amplifier boosts the weak electrical signals from the electrodes.
    • Processing: Processing the amplified signals to understand patterns and activity.
    • Picture/Record: Visual display and recording of the measured brainwaves.
    • Brainwave types:
    • Delta (1.0-4.0 Hz): Sleep, dreaming
    • Theta (4.0-8.0 Hz): Drowsiness
    • Alpha (8.0-12.0 Hz): Reflective, restful
    • Beta (12.0-25.0 Hz): Busy, active mind
    • Gamma (>35 Hz): Problem-solving, concentration

    International 10-20 System

    • System for electrode placement on the head for EEG recordings.
    • Standardized placement locations on the scalp.
    • Numerical percentages for defining locations, e.g., 10%, 20%

    Electrocorticography (ECOG)

    • ECOG, IEEG
    • Intracortical microelectrode: An electrode that is inserted directly into the brain.
    • Grid and stick electrodes: Used in intracortical recordings.
    • Dr. Kareem Zaghloul: Researcher associated with neural signatures of memory and information in the human brain.

    EEG History

    • Detailed history of EEG, including significant developments and key researchers like Hans Berger.
    • Timeline of Technological Advancements:
    • Equipment recordings
    • Evoked potentials
    • Event-related potentials
    • Topographic analyses
    • Computer-aided signal processing
    • Brain-computer interfaces
    • Brain-controlled therapies
    • Personalized medicine
    • Key areas: technology, findings, and applications (1929-1938, 1950, 1960,...1980,.., 1990, 2000, 2010, 2020)

    EEG - Brain Rhythms & Frequency Bands

    • Different brainwave frequencies correlate with different mental states, categorized:
    • Gamma: Problem solving, concentration (Frequency>35Hz)
    • Beta: Busy, active mind (frequency 12-35Hz)
    • Alpha: Reflective, restful (frequency 8-12Hz)
    • Theta: Drowsiness (Frequency 4–8Hz)
    • Delta: Sleep, dreaming (Frequency 0.5–4Hz)

    EEG Recordings During Sleep

    • EEG stages during sleep: Wake, Stage 1, Stage 2, Stage 3, REM, and their characteristic frequency bands

    Recording the Electrical Activity of the Brain

    • Definition of action potential
    • Local field potential
    • Electroencephalogram

    Postsynaptic Potentials (PSPs)

    • Definition of Postsynaptic potentials
    • Relation to chemical transmission at the synapse
    • Duration of PSPs

    Simultaneous EEG-fMRI

    • Advantages and disadvantages of simultaneous EEG and fMRI.
    • Compatibility issues (magnetic fields, RF emissions, materials).
    • Techniques and components for compatibility: electrode cap, connector box, resistors, battery pack, EEG amplifier/digitizer.
    • Main artifacts: gradient, ballistocardiogram (BCG)
    • Artefact correction methods: template, blind source separation, filtering

    Magnetic Properties Relevant to MRI

    • Ferromagnetism: Strongly attracted to magnetic fields (iron).
    • Paramagnetism: Slightly attracted to magnetic fields (gadolinium, deoxyhemoglobin).
    • Diamagnetism: Slightly repelled by magnetic fields (biological tissues).
    • Importance of these properties for device design and interpreting results
    • Definition: neural response associated with a specific sensory, cognitive or motor event.
    • Recording: Average change in voltage over time, starting at stimulus onset, multiple trials
    • Identification of ERP components (e.g., P100, N100, P200, P300) related to sensory properties, selective attention, and endogenous cognitive activity
    • Latency and amplitude as indicators of mental performance and neurobiological vulnerability.

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