Chapter 3: Methods of cognitive neuroscience

Question 1

What does binocular rivalry mean?

Answer 1

Binocular rivalry is a phenomenon that occurs when each eye sees a different image simultaneously.

A single image is perceived and then, after a few seconds, perception switches to the other image. The neural inputs to each eye appear to vie for dominance, presumably entailing a competition between excitatory and inhibitory processes in the visual cortex.

Question 2

What is a block design?

Answer 2

An experimental design used in PET and less commonly with fMRI studies. A block consists of multiple trials of the same type. The activity across the block is averaged and can be compared to activity in another block of a different type of trial.

Question 3

Where does a blood oxygen level-dependent (BOLD) refer to?

Answer 3

BOLD is referring to a change in the magnetic resonance (MR) signal intensity of the hydrogen ion concentration in the brain, which results from changes in the local tissue oxygenation state.

Question 4

What is the process of a blood oxygen level-dependent (BOLD) signal?

Answer 4

Increased neural activity triggers an increase in the amount of oxygenated blood entering local capillaries in the tissue, thus altering the ratio of oxygenated to deoxygenated hemoglobin in the tissue.

Because deoxygenated hemoglobin is paramagnetic, it disrupts the local magnetic properties of the tissue, and the MR signal intensity drops.

Conversely, when oxygenated blood increases in response to local neuron activity, the MR signal intensity increases, and this is known as the BOLD response.

The BOLD signal is an indirect measure of neural activity and is delayed with respect to the neural activity that leads to the BOLD signal, taking about 2-3 seconds to begin, and about 5-6 seconds after the onset of neural activity to peak.

Question 5

What is a cerebral vascular accident?

Answer 5

Stroke, a sudden loss of blood supply to the brain caused by an arterial occlusion or rupture, resulting in cell death and loss of brain function.

Question 6

What is cognitive psychology and what mental operations do cognitive psychologists study?

Answer 6

The branch of psychology that studies how the mind internally represents the external world and performs the mental computations required for all aspects of thinking.

Cognitive psychologists study the vast set of mental operations associated with such things as perception, attention, memory, language, and problem solving.

Question 7

What is a computerized tomography (CT or CAT) scan and how is it an advanced version of a X-ray?

Answer 7

A noninvasive neuroimaging method that provides images of internal structures such as the brain.

CT is an advanced version of the conventional X-ray. Whereas conventional X-rays compress 3D objects into 2D, CT allows for the reconstruction of 3D space from compressed 2D images through computer algorithms.

Question 8

What is a connectivity map (connectome)?

Answer 8

Also named connectome. A visualization of structural or functional connections within the brain.

Question 9

What is deep brain stimulation (DBS) and in which brain area is it used as treatment for Parkinson’s disease?

Answer 9

The electrical stimulation of brain structures via an implanted electrode.

Stimulation of the subthalamic nucleus, one of the nuclei of the basal ganglia, is used as a treatment for Parkinson’s disease.

Question 10

What is a degenerative disorder?

Answer 10

A disorder or disease, either genetic or environmental, in which the function or structure of the affect tissues will continue to deteriorate over time.

Question 11

What is a dependent variable?

Answer 11

The variable in an experiment that is being evaluated by the researcher.

Question 12

What is diffusion tensor imaging (DTI)?

Answer 12

A neuroimaging technique employed using an MRI scanner that allows white matter pathways in the brain to be imaged.

Question 13

What is double dissociation and what does evidence of a double dissociation require?

Answer 13

A method used to develop functional models of mental and/or neural processes.

Evidence of a double dissociation requires a minimum of two groups and two tasks.

Question 14

When is a double dissociation in neuropsychological research present?

Answer 14

In neuropsychological research, a double dissociation is present when one group is impaired on the one task and the other group is impaired on the other task.

Question 15

When is a double dissociation in imaging research present?

Answer 15

In imaging research, a double dissociation is present when one experimental manipulation changes in activation in one neural region and a different manipulation produces changes in activation in a different neural region.

Question 16

Does double dissociation presents strong or weak evidence regarding group differences?

Answer 16

Double dissociations provide a strong argument that the observed differences in performance reflect functional differences between the groups, rather than unequal sensitivity of the two tasks.

Question 17

What is an electrocorticalgraphy (ECoG) and where are the electrodes placed?

Answer 17

A technique to measure the electrical activity of the cerebral cortex. In ECoG, electrodes are placed directly on the surface of the brain, either outside the dura or beneath it.

Question 18

What is an electroencephalography (EEG)? Where are the electrodes placed? And what does the EEG signal include?

Answer 18

A technique to measure the electrical activity of the brain. In EEG, surface recordings are made from electrodes placed on the scalp.

The EEG signal includes endogenous changes in electrical activity (e.g., due to changes in arousal), as well as changes triggered by specific events (e.g., stimuli or movements).

Question 19

What is an event-related design?

Answer 19

An experimental design, used in fMRI studied, in which different types of trials may occur randomly. The BOLD response to particular stimuli or responses can be extracted from signal data.

Question 20

What is an event-related potential (ERP) and what does it reveal in EEG?

Answer 20

A change in electrical activity that is time-locked to specific events, such as the presentation of a stimulus or the onset of a response, embedded within an EEG recording.

When the events are repeated many times, averaging the EEG signals reveals the relatively small changes in neural activity triggered by these events. In this manner, the background fluctuations in the EEG signal are removed, revealing the event-related signal with great temporal resolution

Question 21

What is functional magnetic resonance imaging (fMRI)?

Answer 21

A neuroimaging method that utilizes MRI to track blood flow changes in the brain that are thought to be correlated with local changes in neural activity.

Question 22

What is a hemodynamic response?

Answer 22

A change in blood flow to neural tissues. Hemodynamic responses can be detected by PET and fMRI.

Question 23

What is an independent variable?

Answer 23

The variable in an experiment that is manipulated by the researcher.

Question 24

What is magnetic resonance imaging (MRI) and how does it work?

Answer 24

A neuroimaging technique that exploits the magnetic properties of organic tissue.

Certain atoms are especially sensitized to magnetic forces because of the number of protons and neutrons in their nuclei. The orientation of these atoms can be altered by the presence of a strong magnetic field.

A radio frequency signal can be used to knock these aligned atoms from their orientation in the magnetic field. The atoms will then realign with the magnetic field and give off a radio frequency signal that can be measured by sensitive detectors.

Structural MRI studies usually measure variations in the density of hydrogen ions in the tissue being scanned.
Functional MRI measures changes over time in the signal intensity of the targeted atom.

Question 25

What is a magnetic resonance spectoscopy (MRS)?

Answer 25

A technique to analyze data from MRI that uses signals from hydrogen protons in localized regions of the brain to determine the relative concentrations of different biochemicals.

Question 26

What is a magnetoencephalography (MEG)? How does it work? And how is it used?

Answer 26

A technique that measures magnetic signals generated by the brain.

The electrical activity of neurons produces small magnetic fields that can be measured by sensitive magnetic detectors placed along the scalp, similar to the way EEG measures surface electrical activity.

MEG can be used in an event-related manner similar to ERP studies, with similar temporal resolution. The spatial resolution, in theory, can be superior with MEG because magnetic signals are minimally distorted by organic tissue such as the brain or skull.

Question 27

What is multiunit recording?

Answer 27

A neurophysiological method in which an array of electrodes is inserted in the brain such that the activity of many cells can be recorded simultaneously.

Question 28

What is a multivoxel pattern analysis (MVPA) and what kind of information can it provide?

Answer 28

A pattern classification algorithm in which the researcher identifies the distributed patterns of neural activity consistently present for a particular event, task, stimulus, etc.

These activation patterns can provide information about the functional role of not just brain areas, but of networks within and beyond them.

Question 29

What is a neural network?

Answer 29

A complex network made up of long-distance connections between various brain regions. Neural networks are macrocircuits composed of multiple embedded microcircuits, and they support more complex analyses integrating information processing from many microcircuits.

Question 30

What does optogenetics mean?

Answer 30

A procedure in which genes are manipulated so that they express a photosensitive protein that, when exposed to light, will activate the neuron. The genetic manipulation can be modified such that the protein expression is limited to particular neural regions.

Question 31

What is a pharmalogical study?

Answer 31

An experimental method in which the independent variable is the administration of a chemical agent or drug.

In one example, participants are given drugs that act as dopamine agonists and the observed as they perform decision-making tasks.

Question 32

What is a positron emission tomography (PET) and why is O15 a popular tracer used in neuroscience studies?

Answer 32

A neuroimaging method that measures metabolic activity or blood flow changes in the brain by monitoring the distribution of a radioactive tracer. The PET scanner measures the photons that are produced during the decay of a tracer.

A popular tracer for cognitive neuroscience studies is O15 because its decay time is rapid and the distribution of oxygen increases to neural regions that are active.

Question 33

What is a receptive field and how does it appear in the visual and auditory cortex?

Answer 33

The area of external space within which a stimulus must be presented in order to activate a cell.

For example, cells in the visual cortex respond to stimuli that appear within a restricted region of space. In addition to spatial position, the cells may be selective to other stimulus features, such as color or shape.
Cells in the auditory cortex have also receptice fields. The cell’s firing rate increases when the sound comes from the region of space that defines its receptive field.

Question 34

What is regional cerebral blood flow (rCBF) and how is it used in PET scanning?

Answer 34

The distribution of the brain’s blood supply, which can be measured with various imaging techniques.

In PET scaning, rCBF is used as a measure of metabolic changes following increased neural activity in restricted regions of the brain.

Question 35

What is the retinotopic map?

Answer 35

A topographic representation in the brain in which some sort of orderly spatial relationship is maintained that reflects spatial properties of the environment in an eye-based reference frame.

For example, primary visual cortex contains a retinotopic map of the contralateral side of space, relative to the center of gaze.

Multiple retinotopic maps have been identified in the cortex and subcortex.

Question 36

What is simulation?

Answer 36

A method used in computer modeling to mimic a certain behavior or process. Simulations require a program that explicitly specifies the manner in which information is represented and processed. The resulting model can be tested to see whether its output matches the simulated behavior or process. The program can then be used to generate new predictions.

Question 37

What is single-cell recording and for what can it be used?

Answer 37

A neurophysiological method used to monitor the activity of individual neurons. The procedure requires positioning a small recording electrode either inside a cell or, more typically, near the outer membrane of a neuron.

The electrode measures changes in the membrane potential and can be used to determine the conditions that cause the cell to respond.

Question 38

What is single dissociation? What does evidence of single dissociation require? When is single dissociation present? And provides single dissociation strong or weak evidence regarding group differences?

Answer 38

A method used to develop functional models of mental and/or neural processes. Evidence of a single dissociation requires a minimum of two groups and two tasks.

A single dissociation is present when the groups differ in their performance on one task but not on the other.

Single dissociations provide weak evidence of functional specialization, since it is possible that the two tasks differ in terms of their sensitivity to detect group differences.

Question 39

What is transcranial altering current stimulation (tACS)?

Answer 39

A noninvasive method in which an oscillating low-voltage electrical current is delivered to the brain via electrodes placed on the scalp.

By inducing oscillations at specific frequencies, experimenters can causally link brain oscillations of a specific frequency range to specific cognitive processes.

Question 40

What is transcranial direct current stimulation (tDCS)?

Answer 40

A noninvasive method is which a constant low-voltage electrical current is delivered to the brain via electrodes placed on the scalp.

This method is hypothesized to potentiate neurons near the anodal electrode and to hyperpolarize neurons near the cathodal electrode.

Question 41

What is a transcranial focused ultrasound (tFUS)?

Answer 41

A noninvasive method to stimulate the brain that focuses low-intensity, low-frequency ultrasound extracranially.

This method can produce focal effects limited to a 5-mm area.

Question 42

What is transcranial magnetic stimulation (TMS)? How does it work? And how is it used in clinical and experimental settings?

Answer 42

A noninvasive method used to stimulate neurons in the intact human brain.

A strong electrical current is rapidly generated in a coil placed over the targeted region. This current generates a magnetic field that causes the neurons in the underlying regions to discharge.

TMS is used in clinical settings to evaluate motor function by direct stimulation of the motor cortex.

Experimentally, the procedure is used to transiently disrupt neural processing, thus creating brief, reversible lesions.

Question 43

What is transcranial static magnetic stimulation (tSMS)?

Answer 43

A noninvasive method that uses strong magnets to create magnetic fields that perturb electrical activity and temporarily alters cortical function.

Question 44

What is traumatic brain injury (TBI)?

Answer 44

A form of brain injury resulting from an accident such as a driving accident, a bullet wound, or blast injury. The damage in TBI is diffuse, with both gray and white matter tracts affected by the accelerative forces experienced at the time of injury.

Question 45

What is a voxel?

Answer 45

The smallest unit of 3D data that can be represented in an MRI.