Chapter 2

Question 1

What are the two main approaches for linking cognitive functions and neural processes?

Answer 1

The Brain Perturbation approach and the Neuromonitoring approach

Question 2

Brain Perturbation approach

Answer 2

The brain is perturbed in some way—either by a clinical disorder (e.g., stroke, disease, trauma) or by directed, planned interference (injected drugs, electrical stimulation)—and task performance on a set of cognitive tasks is measured

Question 3

Neuromonitoring approach

Answer 3

An experimenter manipulates a particular cognitive process in an experimental task and measures the associated changes in brain activity

Question 4

What are some examples of Neuromonitoring?

Answer 4

1. Electrical recordings of single units
2. Electrical (EEG) and magnetic (MEG) field recordings
3. Structural Imaging (MRI, CT)
4. Functional Imaging (fMRI, PET)

Question 5

What are some examples of Brain Perturbation?

Answer 5

1. Brain Lesions (natural or induced)
2. Intracranial Stimulation (microstimulation, rTMS, tDCS)
3. Pharmacological Manipulation (drugs)

Question 6

Agonist

Answer 6

A molecule (drug, neurotransmitter) that stimulates the receptors

Question 7

Antagonist

Answer 7

A molecule (drug, neurotransmitter) that blocks receptors

Question 8

Optogenetic modulation

Answer 8

A biological technique to control the activity of neurons or other cell types with light, uses lasers

Question 9

What is Deep Brain Stimulation (DBS) used for?

Answer 9

Parkinson’s Disease, Major Depression

Question 10

Transcranial Magnetic Stimulation (TMS)

Answer 10

A noninvasive form of brain stimulation in which a changing magnetic field is used to cause electric current at a specific area of the brain through electromagnetic induction. Short lasting effects

Question 11

Transcranial direct-current stimulation (tDCS)

Answer 11

A form of neuromodulation that uses constant, low direct current delivered via electrodes on the head. Originally developed to help patients with brain injuries or neuropsychiatric conditions such as major depressive disorder. Short lasting effects

Question 12

Positron Emission Tomography (PET)

Answer 12

A functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption

Question 13

Magnetic Resonance Imaging (MRI)

Answer 13

A structural imaging technique to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body

Question 14

Functional Magnetic Resonance Imaging (fMRI)

Answer 14

A functional imaging technique measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases

Question 15

Dissociations

Answer 15

When damage to a particular area in the brain does NOT disrupt the performance of a specific task, there is a dissociation between the damaged area and the task

Question 16

Associations

Answer 16

When damage to a particular area in the brain disrupts the performance of a specific task, there is an association between the damaged area and the task

Question 17

Double Dissociations

Answer 17

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

Question 19

blood oxygenation level–dependent (BOLD) contrast

Answer 19

A 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 20

coactivation

Answer 20

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 21

computerized tomography (CT)

Answer 21

An imaging method in which

X-rays acquired at multiple angles are used to build a three dimensional structural image of biological tissue.

Question 22

dendritic field potential

Answer 22

An 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 23

diaschisis

Answer 23

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 affected as well.

Question 24

diffusion tensor imaging (DTI)

Answer 24

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

Question 25

dopamine system

Answer 25

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 26

dynamic causal modeling

Answer 26

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 27

event-related design

Answer 27

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 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 28

event-related optical signals (EROS)

Answer 28

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 is electrically active.

Question 29

event-related potential (ERP)

Answer 29

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 30

extracellular recording

Answer 30

Recording the electrical potentials in the extracellular space near active neurons.

Question 31

fiber tract

Answer 31

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

Question 32

fMRI adaptation

Answer 32

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 33

fractional anisotropy (FA)

Answer 33

The 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 34

frequency band

Answer 34

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

Question 35

functional connectivity

Answer 35

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

Question 36

homunculus

Answer 36

Literally “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 37

intracellular recording

Answer 37

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

Question 38

local field potential (LFP)

Answer 38

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

Question 39

magnetoencephalography (MEG)

Answer 39

A 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 40

multivoxel pattern analysis (MVPA)

Answer 40

A 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 41

neuroimaging genomics

Answer 41

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.

Question 42

optogenetics

Answer 42

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 43

peristimulus time histogram (PSTH)

Answer 43

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

Question 44

psychophysiological interaction (PPI) analysis

Answer 44

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 45

repetition suppression

Answer 45

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

Question 46

repetitive TMS (rTMS)

Answer 46

A 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 47

resting-state connectivity

Answer 47

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

Question 48

somatotopic

Answer 48

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 49

structural equation modeling

Answer 49

A 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 50

trial

Answer 50

A single occurrence of an experimental event in a study.

Question 51

tuning curve

Answer 51

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.