Chapter 2: Methods of Cognitive Neuroscience

Question 1

agonist

Answer 1

neuropharmacological agent that mimics the action of a neurotransmitter

Question 2

antagonist

Answer 2

neuropharmacological agent that opposes or interferes with the action of a neurotransmitter

Question 3

blocked design

Answer 3

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 against blocks containing another type of trials, or with a different cognitive condition

Question 4

blood oxygenation level-dependent (BOLD)

Answer 4

measurement of brain activity using fMRI that is based on the local variations in deoxygenated hemoglobin that result from the changes in blood flow induced by neural activity

Question 5

coactivation

Answer 5

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 6

computerized tomography (CT)

Answer 6

imaging method in which X-rays acquired at multiple angles are used to build a three-dimensional structural image of biological tissue

Question 7

dendritic field potentials

Answer 7

electrical potential induced in the dendritic tree of a neuron by input from the axons of other neurons; this electrical activity can often also be detected at the scalp as an EEG or ERP response

Question 8

diaschisis

Answer 8

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 affected as well

Question 9

diffusion tensor imaging (DTI)

Answer 9

method of MRI that can show the preferred directions of diffusion within tissue; useful for the imaging of fiber tracts of the brain

Question 10

dopamine system

Answer 10

refers to the circuits in the brain that include neurons that release the neurotransmitter dopamine. The dopaminergic neurons, which are mostly located in the ventral tegmental area of the midbrain, the substantia nigra pars compacta, and the hypothalamus, have been particularly associated with reward

Question 11

double dissociation

Answer 11

functional relationship in which one 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 12

dynamic causal modelling

Answer 12

successor to structural equation modelling which testsdirectionalmodels 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 13

event-related design

Answer 13

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 from the different events 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

Question 14

event-related optical signals (EROS)

Answer 14

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 is electrically active

Question 15

event-related potential (ERP)

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

extracellular recording

Answer 16

recording the electrical potentials in the extracellular space near active neurons

Question 17

fiber tract

Answer 17

bundles of axons in the brain that carry neuronal signals between brain areas

Question 18

fMRI adaptation

Answer 18

one way of using repetition suppression within an fMRI paradigm that uses pairs of similar stimuli. If the second stimulus induces less activity than the first stimulus (or prime) in a particular brain area, then it can be inferred that the region in some way supports a process common to the two stimuli

Question 19

fractional anisotropy (FA)

Answer 19

degree to which water diffuses in a preferred direction within tissue. Higher levels of fractional anisotropy are thought to reflect greater amounts of white-matter (i.e., fiber tract) integrity

Question 20

frequency bands

Answer 20

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

Question 21

functional connectivity

Answer 21

how the activity of one brain region varies with the activity in other brain regions

Question 22

functional magnetic resonance imaging (fMRI)

Answer 22

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 23

homunculus

Answer 23

“little man” (Greek), often used in referring to the shape of a primary sensory or motor cortical map. Also used to refer (often negatively) to the dualist notion of a non-neurally based “self”

Question 24

intracellular recording

Answer 24

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

Question 25

local field potentials (LFP)

Answer 25

dendritic field potentialthat is recorded intracranially close to the dendritic source (i.e., locally)

Question 26

magnetic resonance imaging (MRI)

Answer 26

noninvasive imaging method based on the behavior of atomic nuclei (particularly hydrogen) within a strong magnetic field; provides excellent soft-tissue contrast of brain anatomy, and can also be used to measure functional brain activity noninvasively

Question 27

magnetoencephalography (MEG)

Answer 27

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

Question 28

multivoxel pattern analysis (MVPA)

Answer 28

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

Question 29

neuroimaging genomics

Answer 29

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

Question 30

optogenetics

Answer 30

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 31

peristimulus time histogram (PSTH)

Answer 31

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

Question 32

positron emission tomography (PET)

Answer 32

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 33

psychophysiological interaction (PPI) analysis

Answer 33

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 34

repetition suppression/ neural priming

Answer 34

phenomenon observed in functional neuroimaging studies in which previously encountered stimuli evoke smaller hemodynamic responses than do novel stimuli

Question 35

repetitive TMS

Answer 35

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

Question 36

resting-state connectivity

Answer 36

patterns of functional connectivity of the brain while a person is awake but not engaged in any specific task or activity

Question 37

somatotopic

Answer 37

refers to a representation of the body mapped on to the cortex of the brain in a topgraphically preserved way, meaning that adjacent locations on the surface of the body have adjacent representations in the cortex, even if perhaps stretched or distorted. The primary motor cortex and the somatosensory area of the brain are two somatotopically organized areas

Question 38

structural equation modeling

Answer 38

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

Question 39

transcranial magnetic stimulation (TMS)

Answer 39

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 typically disrupts the local cortical activity, thereby enabling inferences concerning the cognitive function(s) in which that brain area is involved

Question 40

trial

Answer 40

single occurrence of an experimental event in a study

Question 41

tuning curve

Answer 41

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