Glossary of technical terms in cognitive neuroscience

Abstract

10–20 system An internationally recognized system to determine the location of EEG electrodes on the scalp. Morphologically exactly defined marks are used and electrodes are placed in reference to them in 10 and 20% steps, respectively 3D-MPRAGE A data acquisition sequence that produces detailed, threedimensional high-resolution structural images of the brain AC-PC (anterior to posterior commissure) The anterior commissure (AC) and posterior commissure (PC) are two structures in the brain that are used to define the Talairach coordinate system of the human brain. The anterior commissure is defined as the origin with coordinates (0, 0, 0) Baseline condition Experimental condition designed to provide a baseline measure of brain activity. Since fMRI measures relative states of regional blood flow, such conditions are essential. Common baseline conditions include eyes closed, or fixation (looking at a central point or cross with eyes open) Block Group of experimental trials Block design An fMRI design in which trials of each experimental condition are presented in separate blocks. Different experimental conditions are measured in blocks of trials and the activation associated with these blocks is then analysed BOLD (blood oxygenation level dependency) Oxygenated and deoxygenated hemoglobin differ in the magnetic susceptibility and thus represent a natural contrast agent in fMRI. The ratio of oxygenated to deoxygenated hemoglobin changes R. H. Grabner (&) Institute for Behavioral Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Universitatsstrasse 41, UNO C15, 8092 Zurich, Switzerland e-mail: grabner@ifv.gess.ethz.ch