Neurophysiology and Brain Imaging Quiz
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Questions and Answers

What is the resting membrane potential typically measured at?

  • -70 mV (correct)
  • +30 mV
  • 0 mV
  • -55 mV

    • Which ion is primarily responsible for moving outside the cell due to diffusion?

  • Na+
  • Ca2+
  • Cl-
  • K+ (correct)

    • What must occur for an action potential to be triggered?

  • Threshold must reach +30 mV
  • Threshold must reach -70 mV
  • Threshold must reach -55 mV (correct)
  • Threshold must reach 0 mV

    • What type of receptors are faster and more likely to be involved in signaling?

    <p>Ionotropic receptors (C)</p> Signup and view all the answers

    What primarily maintains the negative membrane potential in a neuron?

    <p>Sodium/Potassium pump (C)</p> Signup and view all the answers

    What happens to Na+ channels when the threshold is reached?

    <p>They open and Na+ enters the cell (B)</p> Signup and view all the answers

    What is the role of electrostatic pressure on Na+ ions?

    <p>It pulls Na+ ions into the cell (B)</p> Signup and view all the answers

    Which statement about ionotropic receptors is true?

    <p>They act faster and are involved in signaling (D)</p> Signup and view all the answers

    What physical phenomenon does MRI rely on to produce images of the brain?

    <p>Hydrogen atom precession in a magnetic field (A)</p> Signup and view all the answers

    Which property differentiates oxygenated from deoxygenated hemoglobin in fMRI?

    <p>Magnetic properties (A)</p> Signup and view all the answers

    How is FDG-PET primarily used to assess brain function?

    <p>By measuring metabolic activity during tasks (A)</p> Signup and view all the answers

    What does diffusion tensor imaging (DTI) primarily measure?

    <p>Directional movement of water molecules (C)</p> Signup and view all the answers

    What aspect of neural activity does fMRI's BOLD signal represent?

    <p>Alterations in hemoglobin magnetic properties (A)</p> Signup and view all the answers

    What is the primary purpose of using regional uptake measurements in Amyloid PET?

    <p>To analyze protein deposits (A)</p> Signup and view all the answers

    In the context of DTI, what does anisotropic diffusion refer to?

    <p>Directional constrainment induced by structures (A)</p> Signup and view all the answers

    What is a common application of PET imaging technology in studying pathologies?

    <p>Binding to specific proteins in the brain (C)</p> Signup and view all the answers

    What is the primary function of Electroencephalography (EEG)?

    <p>Recording electrical potentials in the brain (C)</p> Signup and view all the answers

    Which characteristic of EEG makes it particularly useful for monitoring brain activity over time?

    <p>High temporal resolution (B)</p> Signup and view all the answers

    What are Event-Related Potentials (ERPs) primarily used for?

    <p>Analyzing cognitive processes linked to stimuli (A)</p> Signup and view all the answers

    Which statement about Transcranial Magnetic Stimulation (TMS) is true?

    <p>It may induce seizures in rare preconditions. (C)</p> Signup and view all the answers

    Which condition is NOT typically diagnosed using Computed Tomography (CT) scanning?

    <p>Chronic pain (A)</p> Signup and view all the answers

    What substance is injected during CT Cerebral Angiography?

    <p>Contrast medium (B)</p> Signup and view all the answers

    Which of the following techniques can be used to observe brain functions in a causal manner?

    <p>Transcranial Magnetic Stimulation (TMS) (A)</p> Signup and view all the answers

    What type of imaging does Computed Tomography (CT) utilize?

    <p>X-rays (B)</p> Signup and view all the answers

    What is the primary mechanism responsible for repolarization during an action potential?

    <p>The opening of voltage-gated K+ channels (B)</p> Signup and view all the answers

    What is the role of the Na+/K+ pump in the action potential?

    <p>To maintain the resting membrane potential (D)</p> Signup and view all the answers

    How does the intensity of a stimulus affect the action potential?

    <p>It determines the frequency of action potentials (D)</p> Signup and view all the answers

    What is the significance of the all-or-none law in action potential generation?

    <p>Every action potential has the same amplitude and duration (A)</p> Signup and view all the answers

    Which of the following is NOT a mechanism for terminating neurotransmitter action?

    <p>Active transport of neurotransmitter back into the presynaptic terminal (C)</p> Signup and view all the answers

    What is the role of calcium ions in synaptic transmission?

    <p>They trigger the release of neurotransmitter from presynaptic vesicles (B)</p> Signup and view all the answers

    What is the main advantage of saltatory conduction?

    <p>It allows for faster transmission of action potentials (B)</p> Signup and view all the answers

    Which of the following statements about action potentials is TRUE?

    <p>Action potentials are unidirectional and propagate away from the cell body (A)</p> Signup and view all the answers

    Study Notes

    Quiz Instructions

    • Come to class and get a notecard
    • Write your name on the top left of the notecard
    • Write your student ID on the top right of the notecard

    lonotropic vs Metabotropic Receptors

    • Ionotropic receptors are faster and shorter-acting, involved in signaling and modulation
    • Metabotropic receptors are slower and longer-lasting, involved in signaling and modulation

    Cellular Membrane

    • Phospholipid bilayer
      • Hydrophilic heads
      • Hydrophobic tails

    Cellular Membrane Resting Potential

    • Resting potential is approximately -70mV
    • There is a higher concentration of positive ions outside the cell membrane compared to inside
    • Forces affecting resting potential:
      • Diffusion
      • Electrostatic pressure
      • Sodium (Na+)/Potassium (K+) pump

    Cellular Membrane Opposing Forces

    • K+ is higher inside the cell than outside
      • Diffusion forces K+ outside the cell
      • Electrostatic pressure pulls K+ inside the cell
    • Na+ is higher outside the cell than inside
      • Diffusion forces Na+ inside the cell
      • Electrostatic pressure pulls Na+ inside the cell
    • The Sodium/Potassium pump actively maintains the resting potential by pumping Na+ out and K+ in, against their concentration gradients.

    The Action Potential

    • The action potential begins when a threshold of -55mV is reached
    • Voltage-gated Na+ channels open, causing Na+ influx and depolarization
    • Voltage-gated K+ channels open more slowly, causing K+ efflux and repolarization
    • The membrane returns to rest with the Na+/K+ pump

    The Action Potential - Intensity Coding

    • All-or-none law: The strength of the action potential is independent of the stimulus intensity
    • Intensity is coded by the firing rate of neurons and the number of neurons firing

    Action Potentials are Unitary

    • Action potentials are the same height at the axon terminals as they are at the axon hillock
    • A neuron can generate a greater number of action potentials, but it cannot generate bigger or smaller action potentials

    Saltatory Conduction

    • In myelinated axons, action potentials appear to jump from one node of Ranvier to the next
    • Myelinated segments have no voltage-gated Na+ channels
    • Na+ entering at a previous node sets up a current that flows passively along the myelinated segment

    Synaptic Transmission

    • Release of neurotransmitter molecules allows neurons to communicate
    • Neurotransmitter release requires fusion of synaptic vesicles with the presynaptic membrane and calcium influx
    • Neurotransmitters diffuse across the synaptic cleft and bind to receptors on the postsynaptic membrane

    Terminating Neurotransmitter Action

    • Neurotransmitter effects can be terminated by diffusion, enzymatic degradation, or reuptake
    • Examples of drug targets: Acetylcholinesterase inhibitors and Selective Serotonin Reuptake Inhibitors

    Electroencephalography (EEG)

    • EEG measures electrical potentials in the brain
    • EEG has low spatial resolution but high temporal resolution
    • EEG is used to study sleep, anesthesia, and seizure activity
    • ERPs record brief changes in the EEG signal in response to a stimulus.
    • Stimuli are presented repeatedly and averaged to produce ERPs
    • ERPs can differentiate between different types of stimuli and cognitive processes

    Transcranial Magnetic Stimulation (TMS)

    • TMS stimulates the brain using magnetic pulses
    • TMS is largely noninvasive, but can cause seizures in rare cases
    • TMS can temporarily knock out or enhance function in certain brain regions

    Computerized Tomography (CT)

    • CT scans create cross-sectional images of the brain using X-rays
    • CT scans are used to detect infarctions, tumors, calcifications, hemorrhage, and bone trauma

    CT Cerebral Angiography

    • CT cerebral angiography uses a substance that absorbs X-rays to visualize blood vessels
    • It is an invasive procedure used to diagnose vascular abnormalities, aneurysms, clots, and strokes

    Magnetic Resonance Imaging (MRI)

    • MRI produces brain images by passing a strong magnetic field and radiofrequency pulses through the brain
    • The process measures the energy emitted from hydrogen atoms
    • The technique is used to study brain structure

    Functional MRI (fMRI)

    • fMRI measures brain activity by detecting changes in blood oxygenation (BOLD signal).
    • Neural activity is metabolically demanding and requires oxygen to move into neurons

    Positron Emission Tomography (PET)

    • PET uses radioactively labeled substances to visualize brain activity
    • Active brain areas use more blood, and thus have more radioactive labels
    • Positrons from the radioactivity collide with electrons in the brain to produce photons that exit and are detected

    How PET is used to study pathology

    • Radioactively labeled tracers bind to proteins in the brain
    • Regional uptake can be measured and compared to a reference region to detect brain pathologies

    How FDG-PET is used to study function

    • FDG-PET measures metabolic function in the human brain
    • Researchers can investigate how activity in a particular brain region or condition impacts metabolism
    • FDG-PET is a valuable tool for investigating brain function during stimulation or base conditions

    Diffusion Tensor Imaging (DTI)

    • DTI measures the diffusion of water molecules in the brain to reveal white matter pathways
    • White matter pathways help direct communication and functionality of the nervous system
    • Water molecules move more in constrained directions in the brain, providing structural insight

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    Description

    Test your knowledge on neurophysiology concepts and brain imaging techniques. This quiz covers topics such as resting membrane potential, action potentials, and various imaging modalities like fMRI and DTI. Perfect for students of neuroscience or related fields.

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