neuroscience - neuroimaging techniques

computer tomography (CT)

noninvasive imaging technique where x-rays pass through the brain, and the pattern of light and dark is different depending on what tissue they pass through

magnetic resonance imaging (MRI)

noninvasive imaging technique where radiowaves and a strong magnetic field are used to produce a detailed image of the brain in which different structures look light or dark

diffusion tensor imaging (DTI)

MRI method used to detect directional movements of water molecules to create virtual images of nerve fibers; measures the white matter connectivity between regions

event-related potentials (ERPs)

Based on EEG recordings where the EEG signal is averaged over many events and synchronized to some aspect of the event (e.g., onset of stimulus, pressing a button). Electrodes record a series of positive and negative peaks, where the timing and amplitude of the peaks are related to different aspects of the stimulus and task

positron emission tomography (PET)

radioactive substances (e.g., radioactive form of oxygen) are injected into the blood. As the radioactive substance decays, it gives off photons. Computers detect the origin of the photons and construct an image of the brain

functional magnetic resonance imaging (fMRI)

does not use radioactivity but directly measures the concentration of deoxyhemoglobin in the blood (known as the BOLD response; the blood oxygen level dependent contrast). the change in BOLD response is called the hemodymanic response function and it has a number of distinct phases (not to be confused with the ERP waveform, which is completely unrelated)

transcranial magnetic stimulation (TMS)

coil contains of wire carrying an electric current. a rapid change in the current creates a magnetic field, the magnetic field induces a current in the nearby neurons (causing them to ‘fire’, i.e. generate action potentials). this disrupts the cognitive function that they may be doing at that point in time