H4 The imaged brain

Question 1

structural imaging

Answer 1

measures of the spatial configuration of different types of tissue in the brain (CT & MRI)

Question 2

CT scan

Answer 2

computerized tomography scan → constructed according to amount of X-ray absorption in different types of tissue

Question 3

MRI

Answer 3

magnetic resonance imaging → creates images of soft tissue by applying an alternating magnetic field and a brief radio frequency pulse

Question 4

functional imaging

Answer 4

measures temporary changes in brain physiology associated with cognitive processing (most common= fMRI based on hemodynamic measure)

Question 5

PET scan

Answer 5

positron emission tomography → measures the changes in blood flow to a region directly

Question 6

hemodynamic methods

Answer 6

-PET→ measures changes in blood flow
-fMRI & fNIRS → sensitive to concentration of oxygen in the blood

Question 7

voxel-based morphometry (VBM)

Answer 7

technique for segregating and measuring differences in white and gray matter concentration using MRI

Question 8

voxel

Answer 8

volume-based unit: in imaging research the brain is divided into many thousands of these

Question 9

diffusion tensor imaging (DTI)

Answer 9

uses MRI to measure white matter connectivity between brain regions

Question 10

fractional anisotrophy (FA)

Answer 10

measure of the extent to which diffusion takes place in som directions more than others

Question 11

BOLD

Answer 11

blood oxygen-level-dependent contrast: the signal measured in fMRI that relates to the concentration of deoxyhemoglobin in the blood

Question 12

hemodynamic response function (HRF)

Answer 12

changes in the BOLD signal over time
3 phases: - initial dip
- overcompensation
- undershoot

Question 13

fNIRS

Answer 13

functional near infrared spectroscopy → measures BOLD signal by sending near infrared light instead of magnetic fields BUT can only image shallow neural activity close to scalp

Question 14

cognitive substraction

Answer 14

type of experimental design in functional imaging in which activity in a control task is compared with activity in an experimental task

Question 15

assumption of pure insertion

Answer 15

=pure deletion → assumption that adding a different component to a task doesn’t change the operation of other components

Question 16

cognitive conjuction

Answer 16

method that looks for regions of activation that are shared across several different substractions instead of just 1

Question 17

efference copy

Answer 17

a motor signal used to predict sensory consequences of an action

Question 18

functional integration

Answer 18

the way in which different regions communicate with each other

Question 19

resting state paradigms

Answer 19

technique for measuring functional connectivity in which correlations between several regions/networks are assessed while the participant is not performing any tasks

Question 20

default mode network

Answer 20

set of brain regions that is more hemodynamically active during rest than during tasks

Question 21

stereotactic normalization

Answer 21

the mapping of individual differences in brain anatomy onto a standard template

Question 22

smoothing

Answer 22

redistributing brain activity from neighboring voxels to enhance the signal-to-noice ratio

Question 23

Talairach coordinates

Answer 23

locations in the brain defined relative to the atlas of Talairach and Tournoux

Question 24

inhibition

Answer 24

reduction/suppression of the activity of a brain region, triggered by activity in another region
→presynaptic neurons active; postsynaptic switched OFF

Question 25

excitation

Answer 25

increase of activity of a brain region triggered by activity in another region → presynaptic active; postsynaptic switched ON

Question 26

activation

Answer 26

↑ in physiological processing in 1 condition relative to some other condition(s)

Question 27

deactivation

Answer 27

↓ in physiological processing in 1 condition relative to some other condition(s)

Question 28

semantic dementia

Answer 28

progressive loss of information from semantic memory

Question 29

semantic memory

Answer 29

conceptually based knowledge about the world, including people, places, meaning of objects & words