Chapter 2

Question 1

diaschisis

Answer 1

a disruption of the function of one brain area caused by focal damage to another, distant part of the brain. Often the proper functioning of a brain area relies upon receiving input and stimulation from other, distant areas, so that if a distant area is damaged, the “down-stream” area can be affect as well

Question 2

agonists

Answer 2

a neuropharmacological agent that mimics the action of a neurotransmitter. Compare antagonist.

Question 3

antagonists

Answer 3

a neuropharmacological agent that opposes or interferes with the actions of a neurotransmitter. Compare agonist

Question 4

transcranial magnetic stimulation (TMS)

Answer 4

A method in which a rapidly changing, strong magnetic field is generated next to the skull, thereby delivering transient electrical stimulation to the underlying cortex; the electrical stimulation typical disrupts the local cortical activity, thereby enabling inferences concerning the cognitive function(s) in which that brain area is involved

Question 5

repetitive TMS (rTMS)

Answer 5

A method in which the brain is stimulated by with a repeated sequence of magnetic field pulses, ranging from less than 1 per second up to 30 Hz or more.

Question 6

optogenetics

Answer 6

A method in which genes that code for light-sensitive ion channels or light sensitive ion transporters are introduced into neurons. Once these genes are expressed, and the channels or transporters are integrated into the cell membrane, the neuron’s activity may be controlled by stimulation with light.

Question 7

extracellular recording

Answer 7

recording the electrical potentials in the extracellular space near the active neurons. Compare (intracellular recording)

Question 8

intracellular recording

Answer 8

Recording the potential between the inside and outside of a neuron with a microelectrode

Question 9

peristimulus time histogram (PSTH)

Answer 9

A graph that plots neuronal activity, typically firing rate or number of spikes, as a unction of the time of stimulus presentation.

Question 10

trial

Answer 10

A single occurrence of an experimental event in a study.

Question 11

tuning curves

Answer 11

The function obtained when a neuron’s receptive field is tested with stimuli at different orientations, its peak defines the maximum sensitivity of the neuron in question.

Question 12

dendritic field potentials

Answer 12

An electrical potential induced in the dendritic tree of a neuron by input from the axons of the at the scalp as an EEG or ERP response. Compare local field potentials

Question 13

local field potentials (LFPs)

Answer 13

A dendritic field potential that is recorded intercranially close to the dendritic source.

Question 14

frequency bands

Answer 14

A specific frequency range within a spectrum, usually referring to oscillatory electrical brain activity.

Question 15

event related potentials (ERPs)

Answer 15

Voltage fluctuations in an ongoing brain EEG that are triggered by sensory and/or cognitive events; the changes reflect the summed electrical activity of neuronal populations, specifically responding to those events and are extracted from the ongoing EEG by time-locked averaging.

Question 16

magnetoencephalography (MEG)

Answer 16

A method of measuring at the scalp the electrical currents in the brain based on the detecting of the magnetic fields produced by those currents. Like EEG, MEG activity is thought to reflect mainly the electrical currents produced by dendritic trees of the large pyramidal cells in the cortex.

Question 17

positron emission tomography (PET)

Answer 17

A method of noninvasive hemodynamically based brain imaging that uses radioactively labeled molecules injected into the bloodstream that are taken up to a greater degree by active neurons.

Question 18

blocked design

Answer 18

A task design used in PET studies and sometimes in fMRI studies where multiple trials of the same type are grouped together in blocks. The brain activity is then analyzed by comparing neural activity across the entire block again blocks containing another type of trials, or with different cognitive condition. (Compare event related design)

Question 19

functional magnetic resonance imaging (fMRI)

Answer 19

A non-invasive method for imaging brain activity that uses imaging pulse sequences generated by a magnetic resonance scanner; the signal measured is caused by hemoglobin-based changes in blood oxygenation and blood flow that are induced by local neural activity.

Question 20

blood oxygenation level-dependent (BOLD)

Answer 20

A measurement of brain activity using fMRI that is based on the local variations in deoxygenated hemoglobin that result form the changes in blood flow induced by neuronal activity.

Question 21

event-related design

Answer 21

A task design used in fMRI studies in which trials or events of different types may follow one another in randomized order and the neural responses can be extracted from the measured signals. Analogous to the extraction of event-related potentials (ERPs) from ongoing EEG and to the construction of peristimulus histograms from single neuron recordings. Compare block design.

Question 22

multivoxel pattern analysis (MVPA)

Answer 22

A technique that analyzes patterns of activation across voxels in a particular brain region that consistently correspond to a certain stimulus or event types, rather than the overall increase or decrease in activation of the entire region.

Question 23

repetition suppression

Answer 23

Also called neuronal priming. A phenomenon observed in functional neuroimaging studies in which previously encountered stimuli evoke smaller hemodynamic responses than do novel stimuli. Compare repetition enhancement.

Question 24

fMRI adaptation

Answer 24

A non-invasive method for imaging brain activity that use imaging pulse sequence generated by a magnetic resonance scanner; the signal measured is caused by hemoglobin-based changes in blood oxygenation and blood flow that are induced by local neuronal activity.

Question 25

fiber tracts

Answer 25

Bundles of axons in the brain that carry neuronal signals between brain areas.

Question 26

functional connectivity

Answer 26

How the activity of one brain region varies with the activity in other brain regions.

Question 27

coactivation

Answer 27

Two areas of the brain are said to be coactivated if they both show higher activity in a specific task. Statistically, coactivation is reflected by a positive correlation of activity between two areas.

Question 28

resting-state connectivity

Answer 28

The patterns of functional connectivity of teh brain while a person is awake but not engaged in any specific task or connectivity.

Question 29

psychophysiological interaction (PPI) analysis

Answer 29

An fMRI analysis technique that uses the time courses of activity in different brain areas to analyze how interactions between them differ as a function of the cognitive task being performed. For example, it analyzes whether the correlation in activity between two areas, rather than activity itself, differs in one task versus another.

Question 30

structural equation modeling

Answer 30

A mathematical method of analyzing fMRI data by which two or more models of functional connectivity my be tested against brain data. The method aims at determining the relatively likelihood of one model over another given the observed data.

Question 31

dynamic causal modeling

Answer 31

A successor to structural equation modeling which tests directional models of functional connectivity against brain data to determine the relative likelihood of the activity in one area of the brain causing the activity in others.

Question 32

event related optical signals (EROS)

Answer 32

A noninvasive optical imaging approach based on the fact that when brain tissue is illuminated, even through the skull, the amount of transmitted versus scattered light varies as a function of whether the neuronal tissue in electrically active.

Question 33

double dissociation

Answer 33

A functional relationship in which on area of the brain is experimentally shown to be associated with a particular task or cognitive function and not with another task or function, whereas another area is shown to be involved in the second task or function but not the first. This demonstration thus distinguishes the cognitive roles of different regions in a more rigorous way than does simply showing that the two regions in question respond differently.

Question 34

neuroimaging genomics (imaging genomics)

Answer 34

Also called imaging genomics. A method of relating differences in fMRI activity between people to specific genetic variations. This method can provide accounts of how genetics can influence brain structure and function, and thus in turn, cognitive processes.