Chapter 5 part 1

• X-Ray-Based Techniques:

  • X-ray photography passes an x-ray beam through an object onto a photographic plate, effective in characterizing internal structures that absorb x-rays differently
• Radioactivity-Based Techniques:

  • Positron emission tomography (PET) provides images of brain activity
• Magnetic-Field-Based Techniques:

  • Magnetic resonance imaging (MRI) constructs high-resolution images from radio-frequency waves emitted by hydrogen atoms aligning with a magnetic field
• Ultrasound-Based Techniques:

  • Functional ultrasound imaging (fUS) measures changes in blood volume in specific brain regions using ultrasound
  • fUS is cheap, highly portable, and can be used for imaging individuals who cannot undergo PET or fMRI
• PET, fMRI, and fUS have allowed cognitive neuroscientists to create innovative studies
• P300 wave is a positive deflection occurring about 300 milliseconds after a stimulus, used in ERP studies to investigate cognitive processes like attention and memory
• Transcranial magnetic stimulation (TMS) can turn off an area of the human cortex by creating a magnetic field under a coil positioned next to the skull
• Transcranial electrical stimulation (tES) stimulates an area of the cortex by applying an electrical current through two electrodes placed directly on the scalp
• Transcranial ultrasound stimulation (tUS) can activate particular brain structures, including subcortical structures, and make small permanent lesions to a brain structure
• EEG measures the gross electrical activity of the brain, recorded through large electrodes by an electroencephalograph (EEG machine)
• Signal averaging is a method used to reduce the noise of the background EEG
• Event-related potentials (ERPs) are EEG waves that accompany certain psychological events, showing a correlation between brain activity and cognitive activity
• MEG measures changes in magnetic fields on the scalp produced by underlying patterns of neural activity, with better spatial resolution than EEG
• EMG is the usual procedure for measuring muscle tension, recording the electrical activity between two electrodes taped to the skin over the muscle of interest
• Electrooculography (EOG) records eye movements, with electrodes placed around the eye to measure horizontal and vertical movements
• Skin conductance level (SCL) measures the background level of skin conductance associated with a situation, while skin conductance response (SCR) measures transient changes in skin conductance associated with discrete experiences
• Cardiovascular activity measures include heart rate, arterial blood pressure, and local blood volume
• Computed tomography (CT) is a computer-assisted x-ray procedure that visualizes the brain and other internal structures
• Cerebral angiography uses a radio-opaque dye to visualize the cerebral circulatory system during x-ray photography
• Contrast x-rays involve injecting a substance that heightens contrast between compartments and surrounding tissue
• Diffusion tensor MRI identifies pathways along which water molecules diffuse rapidly, providing an image of major tracts in the brain
• Functional MRI (fMRI) produces images representing the increase in oxygenated blood flow to active areas of the brain
• PET technology is used to identify the distribution of molecules in the brain by injecting volunteers with radioactively labeled ligands
• PET scans show levels of radioactivity in various parts of one horizontal level of the brain
• with heart rate recorded through electrodes on the chest using an electrocardiogram (ECG)