Biopsychology Research Methods

Vocabulary terms and definitions from Chapter 5, covering brain imaging, psychophysiological recording, invasive methods, genetic tools, and behavioral paradigms in biopsychology.

Contrast x-ray techniques

Techniques that involve injecting into one compartment of the body a substance that absorbs x-rays either less than or more than the surrounding tissue to heighten contrast.

Cerebral angiography

A contrast x-ray technique using the infusion of a radio-opaque dye into a cerebral artery to visualize the cerebral circulatory system.

Computed tomography (CT)

A computer-assisted x-ray procedure used to visualize the brain and other internal structures of the living body in three dimensions.

Positron emission tomography (PET)

The first brain-imaging technique to provide functional brain images (images of activity) rather than just structural images.

Fluorodeoxyglucose (FDG)

A radioactive substance similar to glucose that is taken up by active, energy-consuming cells during a PET scan but cannot be metabolized.

Magnetic resonance imaging (MRI)

A structural brain-imaging procedure where high-resolution images are constructed from radio-frequency waves emitted by hydrogen atoms in a powerful magnetic field.

Spatial resolution

The ability of an imaging technique to detect and represent differences in spatial location.

Diffusion tensor MRI

A variation of MRI used to identify pathways along which water molecules rapidly diffuse, providing images of major tracts (bundles of axons).

Connectome

A map of the connections among the structures of the brain.

Functional MRI (fMRI)

An imaging tool that produces images representing the increase in oxygenated blood flow to active areas of the brain.

BOLD signal

The blood-oxygen-level-dependent signal recorded by fMRI, reflecting the difference in magnetic properties between oxygenated and deoxygenated blood.

Temporal resolution

The ability of a technique to specify the timing of neural events; fMRI is noted for being poor in this area, taking $2$ or $3$ seconds to measure a signal.

Functional ultrasound imaging (fUS)

A technique using sound waves of a higher frequency than human hearing to measure changes in blood volume in particular brain regions.

Transcranial magnetic stimulation (TMS)

A technique used to turn off or turn on an area of human cortex by creating a magnetic field under a coil positioned next to the skull.

Transcranial electrical stimulation (tES)

A technique used to stimulate an area of the cortex by applying an electrical current through two electrodes placed directly on the scalp.

Transcranial ultrasound stimulation (tUS)

A technique using low-amplitude ultrasonic sound waves to activate or lesion cortical and subcortical brain structures.

Electroencephalogram (EEG)

A measure of the gross electrical activity of the brain recorded through large electrodes by an electroencephalograph.

Alpha waves

Regular, high-amplitude EEG waves ($8$ to $12$ per second) associated with relaxed wakefulness.

Event-related potentials (ERPs)

EEG waves that accompany specific psychological events, such as the sensory evoked potential elicited by a momentary stimulus.

Signal averaging

A method used to reduce background EEG noise by calculating the mean of many traces to make the average evoked response more apparent.

P300 wave

A positive EEG wave that occurs about $300\,ms$ after a momentary stimulus that has meaning for the participant.

Far-field potentials

Small EEG waves recorded in the first few milliseconds after a stimulus that originate in the sensory nuclei of the brain stem.

Magnetoencephalography (MEG)

A technique measuring changes in magnetic fields on the scalp surface produced by underlying patterns of neural activity.

Electromyography

The standard procedure for measuring muscle tension, resulting in a record called an electromyogram (EMG).

Electrooculography

The electrophysiological technique for recording eye movements, resulting in an electrooculogram (EOG).

Skin conductance level (SCL)

A measure of the background level of skin conductance associated with a particular situation.

Skin conductance response (SCR)

A measure of the transient changes in skin conductance associated with discrete experiences.

Electrocardiogram (ECG or EKG)

A recording of the electrical signal associated with each heartbeat through electrodes on the chest.

Hypertension

A chronic blood pressure of more than $140/90\,mmHg$, viewed as a serious health hazard.

Plethysmography

General techniques for measuring changes in the volume of blood in a particular part of the body.

Stereotaxic atlas

A series of individual maps used to locate brain structures in three dimensions for stereotaxic surgery.

Bregma

The designated reference point on the top of the skull in rat atlases where two major sutures (seams) intersect.

Stereotaxic instrument

A device with a head holder and an electrode holder used to precisely position experimental devices in the depths of the brain.

Aspiration

A lesion method where cortical tissue is drawn off by suction through a fine-tipped handheld glass pipette.

Reversible lesions

Methods for temporarily eliminating activity in a brain area, such as by cooling the structure or injecting an anesthetic like lidocaine.

Cannula

A fine, hollow tube stereotaxically implanted in the brain to administer drugs past the blood-brain barrier.

Neurotoxins

Neural poisons used to make selective chemical lesions, such as kainic acid, ibotenic acid, or 6-hydroxydopamine (6-OHDA).

2-deoxyglucose (2-DG) technique

A method where an animal is injected with radioactive 2-DG and then engages in a task; active neurons absorb the substance but cannot metabolize it.

Autoradiography

The process of coating brain slices with photographic emulsion to develop an image of radioactivity accumulation.

Cerebral dialysis

A method of measuring the extracellular concentration of specific neurochemicals in behaving animals using a semipermeable tube.

Immunocytochemistry

A procedure for locating neuroproteins in the brain by labeling their antibodies with a dye or radioactive element.

In situ hybridization

A technique using labeled hybrid RNA strands to mark the location of neurons releasing specific target neuroproteins.

Gene knockout techniques

Procedures for creating organisms, typically mice, that lack a particular gene under investigation.

Transgenic mice

Mice that contain the genetic material of another species, such as a defective human gene.

CRISPR/Cas9 method

A modern gene editing technique using a Cas9 protein and guide-RNA to activate, inhibit, or edit strands of DNA.

Green fluorescent protein (GFP)

A jellyfish-derived protein that exhibits bright green fluorescence under blue light, used as a research tool to visualize neurons.

Brainbow

A technique where individual neurons are labeled with different colors by expressing varying combinations of mutated fluorescent proteins.

Opsins

Light-sensitive ion channels found in bacteria and algae that can hyperpolarize or depolarize cell membranes when illuminated.

Optogenetics

An emerging field in neuroscience using light and genetic engineering (opsins) to control the activity of specific neurons.

Behavioral paradigm

A single set of procedures developed for the investigation of a particular behavioral phenomenon.

Wechsler Adult Intelligence Scale (WAIS)

An intelligence test routinely given as part of a neuropsychological test battery to provide an IQ score and help interpret other results.

Digit span

The most widely used test of short-term memory, identifying the longest sequence of random digits a patient can repeat correctly $50$ percent of the time.

Token test

A screening test for language-related deficits where a patient follows verbal instructions to touch $20$ tokens of various shapes, sizes, and colors.

Sodium amytal test

An invasive test of language lateralization where an anesthetic is injected into a carotid artery to temporarily silence one hemisphere.

Dichotic listening test

A noninvasive test of language lateralization where different sequences of spoken digits are presented simultaneously to each ear.

Repetition priming tests

Tests used to assess implicit memory by showing patients word fragments to complete after they have studied a list of words.

Constituent cognitive processes

Simple cognitive processes that combine to form complex cognitive processes, each mediated by neural activity in specific brain regions.

Paired-image subtraction technique

A method using functional brain images from two tasks that differ by a single constituent cognitive process to isolate the related brain activity.

Default mode network

A set of brain structures, including the medial parietal and medial prefrontal cortex, that are active when the mind wanders but less active during tasks.

Mean difference image

The result of averaging the subtraction images obtained from various volunteers to emphasize common areas of activity and reduce noise.

Functional connectivity (FC)

The study of how network activity across multiple brain regions is related to a particular cognitive task or the resting state.

Species-common behaviors

Behaviors displayed by virtually all members of a species of the same age and sex, such as grooming, nest building, or copulating.

Open-field test

A behavioral test where an animal's activity and bolus count are recorded in a barren chamber to index fearfulness.

Thigmotaxic

A behavior in fearful rats where they rarely venture away from the walls of a test chamber.

Colony-intruder paradigm

A method for studying aggressive and defensive behavior through encounters between a dominant male rat and a smaller intruder.

Elevated plus maze

A four-armed, plus-sign-shaped maze used as a test of defensiveness or anxiety, often to study the effects of anxiolytic drugs.

Lordosis

The specific posture assumed by a receptive female rat during copulation, involving an arched back and deflected tail.

Intromission

The act of a male inserting his penis into the female's vagina during mounting cycles.

Lordosis quotient

The proportion of mounts that elicit the lordosis posture, used as a measure of female rat sexual behavior.

Self-stimulation paradigm

An operant conditioning paradigm where animals press a lever to deliver electrical stimulation to 'pleasure centers' in their own brains.

Conditioned taste aversion

A seminatural learning paradigm where an avoidance response develops to a food taste followed by illness.

Radial arm maze

A maze with arms radiating from a central area used to study the spatial foraging and navigation abilities of rodents.

Morris water maze

A circular pool of milky water where rats must swim to find an invisible escape platform using external spatial cues.

Conditioned defensive burying

A learning paradigm where rats fling bedding material to bury an object from which they have received an aversive stimulus.

Converging operations

A general approach where multiple research methods are brought to bear on a single problem to provide unequivocal evidence.