The imaged brain Flashcards
Structural imaging
Measures of the spatial configuration of different types of tissue in the brain (principally CT and MRI).
Functional imaging
Measures temporary changes in the brain physiology associated with cognitive processing; the most common method is fMRI and is based on hemodynamic measure.
Voxel-based morphometry (VBM)
A technique for segregating and measuring differences in white matter and gray matter concentration.
Diffusion tensor imaging (DTI)
Uses MRI to measure white matter connectivity between brain regions.
Voxel
A volume-based unit (cf. pixels, which are 2D); in imaging research the brain is divided into many thousands of these.
Fractional anisotropy (FA)
A measure of the extent to which diffusion takes place in some directions more than others.
BOLD
Blood oxygen-level-dependent contrast; the signal measured in fMRI that relates to the concentration of deoxyhemoglobin in the blood.
Hemodynamic response function (HRF)
Changes in the BOLD signal over time.
Cognitive subtraction
A type of experimental design in functional imaging in which activity in a control task is subtracted from activity in an experimental task.
Pure insertion (also pure deletion)
The assumption that adding a different component to a task does not change the operation of other components.
Interactions
The effect of one variable upon another.
Efference copy
A motor signal used to predict sensory consequences of an action.
Functional integration
The way in which different regions communicate with each other.
Resting state paradigm
A technique for measuring functional connectivity in which correlations between several regions (networks) are assessed while the participant is not performing any tasks.
Default mode network
A set of brain regions that is more hemodynamically active during rest than during tasks.
Stereotactic normalization
The mapping of individual differences in brain anatomy onto a standard template.
Smoothing
Redistributing brain activity from neighbouring voxels to enhance the signal-to-noise ratio.
Talairach coordinates
Locations in the brain defined relative to the atlas of Talairach and Tournoux.
Famil Wise Error (FWE)
An approach for correcting for many statistical comparisons based on the number of tests being conducted.
False Discovery Rate (FDR)
An approach for correcting for many statistical comparisons based on the number of positive results obtained.
Inhibition
A reduction/suppression of the activity of a brain region (or a cognitive process), triggered by activity in another region/process.
Excitation
An increase of the activity of a brain region (or a cognitive process) triggered by activity in another region/process.
Activation
An increase in physiological processing in one condition relative to some other condition(s).
Deactivation
A decrease in physiological processing in one condition relative to some other condition(s).
Semantic dementia
A progressive loss of information from semantic memory.
Semantic memory
Conceptually based knowledge about the world, including knowledge of people, places, the meaning of objects and words.
Multi-voxel pattern analysis (MVPA)
An fMRI analysis method in which distributed patterns of activity are linked to cognitive processes
Vegetative state
A disorder of consciousness in which patients with severe brain damage are in a state of partial arousal.
