Principles of fMRI

• What is the process that produces the BOLD signal in fMRI?

  • Neurons fire
  • Dilation of nearby blood vessels occurs
  • Increased blood flow and oxygen delivery happen
  • BOLD signal is detected by fMRI scanners
• If a brain region shows a strong BOLD signal, what can be inferred?

  That region has high neural activity
• What does the BOLD signal indicate in fMRI scans?

  Increased neural activity
• How does fMRI detect brain activity?

  By detecting changes in blood oxygenation
• What are the key components of an fMRI scanner?

  • Magnet provides strong magnetic field
  • Gradient coils control focusing
  • Radio frequency coil emits pulses
  • Scanner collects BOLD signal
• At what time does the BOLD signal typically peak?

  ~5 seconds
• What does the BOLD signal graph indicate about neural activity?

  • Characteristic peak at ~5 seconds
  • Followed by an undershoot (negative phase)
  • Reflects blood oxygen regulation during and after neural activity
• What is the relationship between neural activity and blood flow in fMRI?

  Neural activity leads to increased blood flow
• What does the undershoot in the BOLD signal represent?

  Blood oxygen regulation during and after neural activity
• How does vasodilation differ between young and older adults?

  • Young adults: Standard vasodilation matching neural activity
  • Older adults: Greater vasodilation response
• What does the BOLD signal measure?

  Changes in brain blood oxygenation levels
• What does the participant do during the functional scan?

  Performs specific tasks or observes stimuli
• What does BOLD stand for in fMRI scans?

  Blood Oxygen Level Dependent
• What triggers dilation in nearby blood vessels during fMRI?

  Firing of neurons
• What does the radio frequency coil in an fMRI scanner emit?

  Pulses
• What happens to blood vessels with increased neuronal activity?

  Blood vessels widen, increasing blood flow
• What happens to blood flow when neurons fire?

  Blood flow increases to active brain regions
• What is the term for the dilation of blood vessels?

  Vasodilation
• What is the role of gradient coils in an fMRI scanner?

  They control focusing
• Why is a baseline activity scan taken during an fMRI scan?

  To establish normal brain activity
• What is the primary purpose of fMRI?

  To measure brain activity through blood oxygenation
• What is the first step in an fMRI scan?

  Place the participant on a table
• What does fMRI stand for?

  Functional magnetic resonance imaging
• What can fMRI reveal about brain activity?

  • Active brain regions during tasks
  • Comparison of activity in different tasks
  • Example: reading vs. speaking
• How can fMRI scans be used to compare brain activity?

  By comparing scans during different tasks
• What is the relationship between neural activity and blood oxygenation?

  Neural activity causes vasodilation, increasing blood oxygenation
• What contributes to varying BOLD signals in fMRI scans across age groups?

  The difference in vasodilation response
• What happens when neurons fire?

  They release chemicals causing blood vessels to dilate
• What is conducted after the baseline activity scan in an fMRI procedure?

  A functional scan
• What type of signal does the scanner collect during an fMRI scan?

  BOLD signal
• What is the difference between oxygenated and deoxygenated hemoglobin?

  Oxygenated hemoglobin has different magnetic properties
• How do the components of an fMRI scanner work together?

  Magnet creates field, coils focus, coil emits
• What does the magnet in an fMRI scanner do?

  Provides a strong magnetic field
• How does the BOLD signal appear in brain scans?

  As brighter areas in brain scans