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)