Chapter 5

2-deoxyglucose,

2-DG

head holder

A ______, which firmly holds each subject's brain in the prescribed position and orientation.

Sensory evoked potential.

A change in the electrical activity of the brain (e.g., in the cortical EEG) that is elicited by the momentary presentation of a sensory stimulus.

Computed tomography (CT).

A computer-assisted x-ray procedure that can be used to visualize the brain and other internal structures of the living body. 3D representation of the brain

Cerebral angiography.

A contrast x-ray technique for visualizing the cerebral circulatory system by infusing a radio-opaque dye into a cerebral artery.

Stereotaxic instrument.

A device for performing stereotaxic surgery, composed of two parts: a head holder and an electrode holder.

Cannula.

A fine, hollow tube that is implanted in the body for the purpose of introducing or extracting substances.

immunocytochemistry in situ hybridization.

A key step in trying to understand the psychological function of a particular neurotransmitter or receptor is finding out where it is located in the brain. Two of the techniques available for this purpose are ________ and _______

Aspiration.

A lesion technique in which tissue is drawn off by suction through the fine tip of a glass pipette.

Diffusion tensor imaging.

A magnetic resonance imaging (MRI) technique that is used for identifying major tracts.

Functional MRI (fMRI).

A magnetic resonance imaging technique for inferring brain activity by measuring increased oxygen flow into particular areas.

Skin conductance level (SCL).

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

Cerebral dialysis.

A method for recording changes in brain chemistry in behaving animals in which a fine tube with a short semipermeable section is implanted in the brain and extracellular neurochemicals are continuously drawn off for analysis.

Signal averaging.

A method of increasing the signal-to-noise ratio by reducing background noise.

Optogenetics.

A method that uses genetic engineering techniques to insert the opsin gene, or variants of the opsin gene, into particular types of neurons. By inserting an opsin gene into a particular type of neuron, a researcher can use light to hyperpolarize or depolarize those neurons.

Fluorodeoxyglucose (FDG).

A molecule that is similar to glucose, and is thus rapidly taken up by active cells. However, unlike glucose, fluorodeoxyglucose cannot be metabolized; it therefore accumulates in active cells until it is gradually broken down. A radioactive isotope of this molecule is commonly used in positron emission tomography (PET).

total

A multiple-unit recording is a graph of the _______ number of recorded action potentials per unit of time

Immunocytochemistry.

A procedure for locating particular proteins in the brain by labeling their antibodies with a dye or radioactive element and then exposing slices of brain tissue to the labeled antibodies.

Electromyography EMG electromyogram (EMG)

A procedure for measuring muscle tension. The resulting record is called an ________ .

Green fluorescent protein (GFP).

A protein that is found in certain species of jellyfish and that fluoresces when exposed to blue light.

Electrocardiogram (ECG or EKG).

A recording of the electrical signals associated with heartbeats.

6-hydroxydopamine

A selective neurotox.in that has been widely used is ______ (6-OHDA), which is taken by by only those neurons that release the neurotransmitter norepinephrine or dopamine

Stereotaxic atlas.

A series of maps representing the three-dimensional structure of the brain that is used to determine coordinates for stereotaxic surgery.

reds yellows

A series of two PET scans. A scan was done when the volunteer's eyes were either open (left) or closed (right). Areas of high activity are indicated by ____ and _____. For example, notice the high level of activity in the visual cortex of the occipital lobe when the volunteer's eyes were open

Magnetic resonance imaging (MRI).

A structural brain imaging procedure in which high-resolution images are constructed from the measurement of waves that hydrogen atoms emit when they are activated by radio-frequency waves in a magnetic field.

In situ hybridization.

A technique for locating particular proteins in the brain; molecules that bind to the mRNA that directs the synthesis of the target protein are synthesized and labeled, and brain slices are exposed to them.

Magnetoencephalography (MEG).

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

Electrooculography.

A technique for recording eye movements through electrodes placed around the eye.

Electroencephalography.

A technique for recording the gross electrical activity of the brain through electrodes, which in humans are usually attached to the surface of the scalp.

Positron emission tomography (PET).

A technique for visualizing brain activity, usually by measuring the accumulation of radioactive fluorodeoxyglucose (FDG) in active areas of the brain.

Transcranial direct current stimulation (tDCS).

A technique that can be used to stimulate ("turn on") an area of the cortex by applying an electrical current through two electrodes placed directly on the scalp.

Transcranial magnetic stimulation (TMS).

A technique that can be used to stimulate ("turn on") or turn off an area of the cortex by creating a magnetic field under a coil positioned next to the skull.

Spatial resolution.

Ability of a recording technique to detect differences in spatial location (e.g., to pinpoint a location in the brain).

Temporal resolution.

Ability of a recording technique to detect differences in time (i.e., to pinpoint when an event occurred).

electrode holder

An holder, which holds the device to be inserted.

Plethysmography.

Any technique for measuring changes in the volume of blood in a part of the body.

black

Areas of the brain that absorbed high levels of radioactive 2-DG during the test appear as _____ spots on the slides.

enzymes

Because all enzymes are proteins and because only those neurons that release a particular neurotransmitter are likely to contain all the enzymes required for its synthesis, immunocytochemistry can be used to locate neurotransmitters by binding to their _______.

brainbow

By making minor alteration to the GFP, scientist synthesized proteins that fluoresced in different fluorescent colors: cyan, yellow, and blue.

computed tomography,

CT:

vascular blood vessels

Cerebral angiograms are most useful for localizing _____ damage, but the displacement of ______ from their normal position also can indicate the location of a tumor.

Hypertension.

Chronically high blood pressure.

bipolar electrode

Clues about the function of a neural structure can be obtained by stimulating it electrically. Electrical brain stimulation is usually delivered across the two tips of a _________—two insulated wires wound tightly together and cut at the end. Weak pulses of current produce an immediate increase in the firing of neurons near the tip of the electrode.

invasive EEG recording

EEG signals are recorded through large implanted electrodes rather than through scalp electrodes.

Far-field potentials.

EEG signals recorded in attenuated form at the scalp because they originate far away—for example, in the brain stem.

radioactivity brain image

Each PET scan is merely a colored map of the amount of ______ in each of the tiny cubic voxels (volume pixels) that compose the scan. Exactly how each voxel maps onto a particular brain structure can be estimated only by superimposing the scan on a _____.

all-or-none tone (tension)

Each skeletal muscle is composed of millions of threadlike muscle fibers. Each muscle fiber contracts in an _____ fashion when activated by the motor neuron that innervates it. At any given time, a few fibers in each resting muscle are likely to be contracting, thus maintaining the overall ______ of the muscle.

Melanopsin knockout mice (mice in whom the gene for the synthesis of melanopsin has been deleted) to studythe role of melanopsin in regulating the light-dark cycles that control circadian (about 24 hours) rhythms of bodily function.

Example of Gene knockout techniques.

Example of optogenetics

For example, it can be used in living animals by injecting the animal with a virus carrying an opsin gene that targets a particular type of neuron. An optical fiber can then be implanted in the animal and light can be shone through the fiber to activate the opsin ion channels—causing the activity of specific neurons to either be increased or suppress

aspiration lesions radio-frequency lesions knife cuts reversible lesions.

Four types of lesions are discussed:

(1) Nothing has to be injected into the volunteer; (2) it provides both structural and functional information in the same image; (3) its spatial resolution is better; and (4) it can be used to produce three-dimensional images of activity over the entire brain.

Functional MRI has four advantages over PET:

vertical

It is usual to record EOG activity between two electrodes placed on each side of the eye to measure its horizontal movements and between two electrodes placed above and below the eye to measure its ______ movements.

Opsins.

Light-sensitive ion channels that are found in the cell membranes of certain bacteria and algae. When opsins are illuminated with light, they open and allow ions to enter the cell.

magnetic resonance imaging

MRI

BOLD signal

MRIs are not images of neural activity, but images of _______.

systoles diastoles

Measuring arterial blood pressure involves two independent measurements: a measurement of the peak pressure during the periods of heart contraction, the _______, and a measurement of the minimum pressure during the periods of relaxation, the ______.

Reversible lesions.

Methods for temporarily eliminating the activity in a particular area of the brain while tests are being conducted.

Transgenic mice.

Mice into which the genetic material of another species has been introduced.

connectome

Most brain research focuses on the structures of the brain. However, in order to understand how the brain works, it is also important to understand the connections among those structures—the so-called _______ .

lesion methods electrical stimulation methods, invasive recording

Most physiological techniques used in biopsychological research on laboratory animals fall into one of three categories: _______, ________, and _______ methods.

smooth curve

Most psychophysiologists do not work with raw EMG signals; they convert them to a more workable form. The raw signal is fed into a computer that calculates the total amount of EMG spiking per unit of time—in consecutive 0.1-second intervals, for example. The integrated signal (i.e., the total EMG activity per unit of time) is then plotted. The result is a m ________ , the amplitude of which is a simple, continuous measure of the level of muscle tension.

large

Movement results when a _______ number of fibers contract at the same time.

Neurotoxins.

Neural poisons.

positron emission tomography

PET

Gene replacement techniques.

Procedures for creating organisms in which a particular gene has been replaced with another.

Gene knockout techniques.

Procedures for creating organisms that lack a particular gene.

Alpha waves.

Regular, 8- to 12-per-second, high-amplitude EEG waves that typically occur during relaxed wakefulness and just before falling asleep.

Signal averaging: averaging of auditory evoked potentials. Averaging increases the signal-to-noise ratio

Signal averaging: averaging of auditory evoked potentials. Averaging increases the signal-to-noise ratio

Event-related potentials (ERPs).

The EEG waves that regularly accompany certain psychological events.

signal noise

The ______ is the part of any recording that is of interest; the ______ is the part that isn't.

2-deoxyglucose (2-DG) metabolize

The ________ technique entails placing an animal that has been injected with radioactive 2-DG in a test situation in which it engages in an activity of interest. Because 2-DG is similar in structure to glucose—the brain's main source of energy—neurons active during the test absorb it at a high rate but do not ________ it.

bilateral unilateral

The behavioral effects of unilateral lesions (lesions restricted to one half of the brain) are much milder than those of symmetrical bilateral lesions (lesions involving both sides of the brain), particularly in nonhuman species. Indeed, behavioral effects of unilateral lesions to some brain structures can be difficult to detect. As a result, most experimental studies of lesion effects are studies of _______ , rather than ____, lesions.

BOLD signal.

The blood-oxygen-level-dependent signal that is recorded by functional MRI (fMRI).

Neurotoxins

The effects of surgical, radio-frequency, and reversible lesions are frequently difficult to interpret because they affect all neurons in the target area. This is why scientist sometimes use________ that have an affinity for certain components of the nervous system.

intracellular unit recording extracellular unit recording multiple-unit recording invasive EEG recording.

The four invasive electrophysiological recording methods:

Example of brainbow

The modified GFP was inserte into the genomes of developing mice and expressed by labeling neurons in distintive colors. The pathways of neural axons could be traced to their destinations through the cellular morass.

Bregma.

The point on the surface of the skull where two of the major sutures intersect; commonly used as a reference point in stereotaxic surgery on rodents.

P300 wave.

The positive EEG wave that usually occurs about 300 milliseconds after a momentary stimulus that has meaning for the subject.

extracellular unit recording

The record the action potentials of a neuron through a microelectrode whose tip is positioned in the extracellular fluid next to it—each time the neuron fires, there is an electrical disturbance and a blip is recorded at the electrode tip

Autoradiography.

The technique of photographically developing brain slices that have been exposed to a radioactively labeled substance (such as 2-deoxyglucose) so that regions of high uptake are made visible.

Skin conductance response (SCR).

The transient change in skin conductance associated with discrete experiences.

consciousness or particular types of cerebral pathology

The utility of the scalp EEG does not lie in its ability to provide an unclouded view of neural activity. Its value as a research and diagnostic tool rests on the fact that some EEG wave forms are associated with particular states of ______ or particular types of ________ (e.g., epilepsy).

resting

This usage acknowledges the fact that anxious or otherwise aroused individuals typically display high ______ levels of tension in their muscles.

Example of gene replacement

Transgenic mice by inserting a defective human gene associated with schizophrenia. The transgenic mice displayed a variety of cerebral abnormalities (e.g., reduced cerebral cortex and enlarged ventricles) and atypical behaviors reminiscent of human schizophrenia.

Cannula

When doing psychopharmacological experiments, scientists overcome the problem of the blood-brain barrier by administering small doses of the drug through _________

Contrast x-ray techniques.

X-ray techniques that involve the injection, into one compartment of the body, of a substance that absorbs x-rays either less than or more than surrounding tissues.

PET and fMRI correlation

____ and ____ have allowed cognitive neuroscientists to create images of brain activity while volunteers are engaging in particular cognitive activities. They can be used to show a ______ between brain activity and cognitive activity

Positron emission tomography (PET)

_____ was the first brain-imaging technique to provide images of brain activity (functional brain images) rather than images of brain structure (structural brain images).

Cortical subcortical

______ EEG signals are frequently recorded through stainless steel skull screws, whereas _______ EEG signals are typically recorded through stereotaxically implanted wire electrodes.

fluorodeoxyglucose (FDG)

______ is injected into the patient's carotid artery (an artery of the neck that feeds the ipsilateral cerebral hemisphere)

Plethysmos

______ means "an enlargement".

Egas Moniz

_______ , the inventor of the lobotomy was also the pioneer of cerebral angiography.

intracellular unit recording

provides a moment-by-moment record of the graded fluctuations in one neuron's membrane potential.

multiple-unit recording

the electrode tip is much larger than that of a microelectrode; thus, it picks up signals from many neurons, and slight shifts in its position due to movement of the subject have little effect on the overall signal. The many action potentials picked up by the electrode are fed into an integrating circuit, which adds them together.

The general strategy is to activate the GFP gene in only the particular cells under investigation so that they can be readily visualized. to visualize neurons

what is one of the current uses for GFP?