Module 6

Question 1

The very first requirement to obtain approval for conducting research using animals is that the science itself has been reviewed and judged to be sound and important. How is this done? How are research grants identified as having high scientific merit?

Answer 1

1) The leading researcher (who is often called “principal investigator”, or PI) who is overseeing the project program has obtained a research grant, that is, funding from an external organization to pay for the cost of the research.

2) In Canada, the main federal research agencies are NSERC (fundamental, basic research in the areas of biopsychology and neuroscience, including animal research), CIHR (Clinical, disease-oriented neuroscientific (human and non-human) research), and SSHRC (does not cover animal research).

Question 2

True or False?

Even after a PI has successfully obtained an external research grant, they still need to obtain permission to conduct their research at the institution.

Answer 2

True.

The review and monitoring of animal research activities at universities is conducted by the University Animal Care Committee (UACC); federal laws and regulation mandate that each university has its own UACC.

The UACC also reviews and monitors the use of animals in teaching, such as lab courses that involve work or demonstrations with animals.

Question 3

The use of animals in science at Queen’s is done with the supervision and approval of the Canadian Council on Animal Care (CCAC). What is the CCAC?

Answer 3

A Canadian peer-reviewed organization responsible for setting, maintaining, and overseeing the implementation of high standards for animal ethics and care in science on a national scale.

The goal of the CCAC guidelines is to strive for best research practices and optimal conditions for the animals, through constant improvement as new information on animal well-being and health becomes available. Compliance with and approval of the CCAC is mandatory in order to receive federal funding, the highest source of funding for most Canadian universities. Failure to comply with the CCAC can lead to a suspension of animal care and research programs at the university.

Question 4

Why are animals used in research?

Answer 4

Pre-clinical trials on animals are often a legal requirement before the drug can be put to use. Regulatory agencies in most countries require evidence of drug safety before they can be used with humans and in many cases this pre-clinical testing is done on animals.

Animals are often the most valuable way to study the effects of how organ systems in the body interact with each other and to learn about the side effects that might occur with a particular treatment.

In the research path to the discovery of, for example, a better treatment for hypertension, some studies might be done in cell or tissue culture, then in animals, and ultimately in humans. Such clinical trials are very carefully regulated.

Many techniques and vaccines developed through animal research are applied to animal health practices as well as in human medicine. In this way, developments made with animal research can also benefit animals.

Question 5

What is The University Animal Care Committee (UACC) ?

Answer 5

is a Principal’s committee that reports to the Vice Principal (Research). The UACC is mandated by the Animals for Research Act (ARA) which is administered by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and the Canadian Council on Animal Care (CCAC). The UACC is responsible for the review of all protocols proposing the use of animals in research, teaching, or testing at or in direct affiliation with Queen’s University.

The role of the Committee is to ensure that the welfare of the animals is a prime consideration in their procurement, care and use and that the highest ethical standards, as defined by the Canadian Council on Animal Care (CCAC), are observed.

Question 6

What are the UACC’s objectives?

Answer 6

1) To ensure that the use of animals at Queen’s University in research, teaching or testing meets or exceeds the standards of animal welfare established by the Animals for Research Act (Ontario), and the Canadian Council on Animal Care (CCAC).

2) To teach and promote the ethical use and management of animals in research, teaching and testing by providing training opportunities to personnel engaged in the care and research of animals.

3) To encourage good communication between animal users and the UACC, and to work with investigators and instructors to create a research and teaching environment that promotes animal welfare.

4) To work with the Canadian Council on Animal Care (CCAC) and the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) to ensure that all animal care facilities at Queen’s University meet or exceed the standards of care set by agency guidelines and legislation, and to report accurate numbers of animals used in research and teaching to these agencies.

Question 7

The UACC plays a critical role in not only the approval of research project, but also the monitoring of ongoing research activities by doing what?

Answer 7

They will visit labs and observe procedures being conducted on animals and ensure that the actual lab procedures match those that the UACC has approved, and that animals are always monitored for their health status and maintained under the best housing and environmental conditions.

Question 8

What are the 3 R’s of ethical animal experimentation?

Answer 8

Replacement - whenever possible, replace use of animals with other models.

Reduction - reduce the numbers of animals used.

Refinement - methods to improve animal welfare (better housing, handling, pain relief, shorter experiments etc)

Question 9

You are a biopsychologist who has discovered a novel neurotransmitter substance (transmitter X) released by cortical neurons. Nothing is known about the transmitter and you are preparing a grant application entitled: “The physiological and behavioural functions of transmitter X in the rodent brain”. You likely will submit this grant application to:

SSHRC

CIHR

NSERC

Queen’s University

Answer 9

NSERC

Question 10

The Canadian Council on Animal Care (CCAC) is:

a). the committee at Queen’s that oversees the use of animals for research and teaching purposes

b). a national organization with a mandate to set standards for the care and use of animals in research in Canada

c). will review and approve animal procedures conducted at Queen’s and other universities

d). both (a) and (c) are correct

Answer 10

b). a national organization with a mandate to set standards for the care and use of animals in research in Canada

Question 11

The University Animal Care Committee (UACC) of Queen’s…

reviews all research or teaching procedures carried out by Queen’s University personnel on animals

reviews research or teaching procedures on animals carried out only at Queen’s University

conducts unannounced inspections of Ontario universities on a yearly basis

reviews and approve animal procedures conducted at Queen’s and other universities

Answer 11

reviews all research or teaching procedures carried out by Queen’s University personnel on animals

Question 12

The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA)…

conducts unannounced inspections of Ontario universities on a yearly basis

reviews animal procedures conducted at Ontario universities

offers training workshops to improve animal handling and experimental skills and techniques

all of the above are correct

Answer 12

conducts unannounced inspections of Ontario universities on a yearly basis

Question 13

The 3Rs of ethical animal research stand for…

reduce redundancies and replication

replace, reduce, and refine

reduce, reuse, and recycle

regulation, reconstruction, and resilience

Answer 13

replace, reduce, and refine

Question 14

As an animal researcher, you have introduced the use of a powerful and long-lasting analgesic drug, to be used after the surgical implantation of recording electrodes into the brain of rats. This is an example of…

Reduction

Replacement

Refinement

All of the above

Answer 14

Refinement

Question 15

Let’s start with the idea of standardization by running through a hypothetical experiment.

Answer 15

1) First, imagine that you are a scientist working for a pharmaceutical company and you have developed a new compound (“drug N”). This compound acts as a strong and highly selective agonist at GABA receptors in the brain. (Drugs that act as GABA receptor agonist are used to treat anxiety disorders.)

2) You will probably want to explore if drug N has anxiety-reducing properties in an animal model, such as the elevated plus maze (EPM). Before testing the actual drug, you want to establish the “baseline” levels of open arm exploration in control (i.e., no drug treatment) animals. Just to be on the safe side and ensure that you can obtain consistent and reliable levels of baseline open arm exploration (and, thus, anxiety level), you actually decide to run two control groups, each of the two control groups consists of 12 rats.

3) It is desirable to have control/comparison conditions that show relatively little variability, in other words, scientists often hope for a “stable, consistent” baseline or control condition to which they then compare the group that receives an experimental manipulation (e.g., drug treatment).

How do we achieve such stable, tight control conditions? This is where standardization comes into play. By standardizing various experimental and other conditions, we hope to reduce the variability of a data set.

Question 16

What can standardization involve?

Answer 16

1) Consistent/identical housing conditions for all animals.

2) Consistent/identical food and water supply. (For example, hunger can increase the open arm time in EPM.

3) Consistent/identical environmental conditions like room temp, lighting, humidity. (For example, reduced lighting increases open arm exporation)

4) Consistent/identical test conditions and apparatus. (Ie: the same maze)

5) Consistent/identical behavioral testing conditions (ie: time of day)

6) Consistent/identical age groups of experimental animals

7) Using animals of only one sex

Question 17

What are 4 different sorts of methods for visualizing the living human brain?

Answer 17

x-ray-based techniques,

a radioactivity-based technique,

magnetic-field- based techniques,

an ultrasound-based technique.

Question 18

Describe two x-ray-based techniques for visualizing the living human brain.

Answer 18

1) CONTRAST X-RAYS - injecting into one compartment of the body a substance that absorbs x-rays either less than or more than the surrounding tissue. The injected substance then heightens the contrast between the compart- ment and the surrounding tissue during x-ray photography.
One contrast x-ray technique, cerebral angiography, uses the infusion of a radio-opaque dye into a cerebral artery to visualize the cerebral circulatory system during x-ray photography. Cerebral angiograms are most useful for localizing vascular damage, but the dis- placement of blood vessels from their normal position also can indicate the location of a tumor.

2) COMPUTED TOMOGRAPHY (CT) - is a computer-assisted x-ray procedure that can be used to visualize the brain and other internal structures of the living body. During cerebral computed tomography, the neurological patient lies with his or her head positioned in the center of a large cylinder. On one side of the cylinder is an x-ray tube that proj- ects an x-ray beam through the head to an x-ray detector mounted on the other side. The x-ray tube and detector rotate rapidly around the head of the patient at one level of the brain, taking many individual x-ray photographs as they rotate. The meager information in each x-ray photograph is combined by a computer to generate a CT scan of one horizontal section of the brain. Then the x-ray tube and detector are moved along the axis of the patient’s body to another level of the brain, and the process is repeated. Scans of eight or nine horizontal brain sections are typically obtained from a patient. When combined, these images provide three-dimensional representations of the brain.

Question 19

Describe the positron emission tomography (PET) technique.

Answer 19

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

-a colored map of the amount of radioactivity in each of the tiny cubic voxels (volume pixels)

-Radioactive fluorodeoxyglucose (FDG) is injected into the patient’s carotid artery. Because of its similarity to glucose, the primary metabolic fuel of the brain, fluorodeoxyglucose is rapidly taken up by active (energy-consuming) cells and cannot be metabolized; so it accumulates in active neurons and astrocytes until it is gradually broken down.

-Current application of PET technology is its use in identifying the distribution of particular molecules (e.g., neurotransmitters, receptors, transporters) in the brain by injecting volunteers with radioactively labeled ligands (ions or molecules that bind to other molecules). Then, PET scans can document the distribution of radioactivity in the brain.

Question 20

Describe Magnetic resonance imaging (MRI).

Answer 20

• structural brain-imaging procedure in which high-resolution images are constructed from the measurement of radio-frequency waves that hydrogen atoms emit as they align with a powerful magnetic field.

-Such imaging is possible because: (1) water contains two hydrogen atoms (H2O) and (2) different brain structures contain different amounts of water. This, in turn, means that the number of hydrogen atoms differs between brain structures, and, therefore, the radio-frequency waves emitted by a particular brain structure will be different from its neighboring brain structures.

-MRI provides clearer images of the brain than does CT

-Provides HIGH spatial resolution (the ability to detect and represent differences in spatial location), MRI can produce images in 3D

Question 21

Describe diffusion tensor MRI.

Answer 21

• a method of identifying those pathways along which water molecules rapidly diffuse. Because tracts (bundles of axons) are the major routes of rapid water diffusion in the brain, diffusion tensor imaging provides an image of major tracts.

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

Question 22

Describe functional MRI.

Answer 22

-produces images representing the increase in oxygenated blood flow to active areas of the brain.

• Functional MRI is possible because of two attributes of oxygenated blood. First, active areas of the brain take up more oxygenated blood than they need for their energy requirements, and thus oxygenated blood accumulates in active areas of the brain. Second, oxygenated blood has different magnetic properties than does deoxygenated blood, and this difference influences the radio-frequency waves emit- ted by hydrogen atoms in an MRI.

-The signal recorded by fMRI is called the BOLD signal (the blood-oxygen-level-dependent signal). The BOLD signal indicates the parts of the brain that are active or inactive during a cognitive or behavioral test, and thus it suggests the types of analyses the brain is performing.

• Because the BOLD signal is the result of blood flow through the brain, it is important to remember that it is not directly measuring the electrical activity of the brain.

Question 23

What 3 advantages does a Functional MRI have over PET?

Answer 23

(1) nothing has to be injected into the volunteer;
(2) it provides both structural and functional information in the same image; and
(3) its spatial resolution is better.

Question 24

True or False?

fMRI produces actual pictures of human neural activity.

Answer 24

False.

They are images of the BOLD signal, and the relation between the BOLD signal and neural activity is complex . Furthermore, fMRI technology has poor temporal resolution, that is, it is poor at specifying the timing of neural events. Indeed, it takes 2 or 3 seconds to measure the BOLD signal, and many neural responses, such as action potentials, occur in
the millisecond range.

Question 25

Describe an ultrasound-based technique for imaging the living human brain.

Answer 25

Functional ultrasound imaging (fUS) is a new imaging technique that uses ultrasound (sound waves of a higher frequency than we can hear) to measure changes in blood volume in particular brain regions. When a brain region becomes active, blood levels increase there, and alter the passage of ultrasound through that brain region.

Question 26

As a functional brain imaging method, fUS (functional ultrasound imaging) has what three key advantages over PET and fMRI?

Answer 26

(1) it is cheap, (2) highly portable; and (3) can be used for imaging some individuals, such as human infants, who cannot undergo PET or fMRI.

Question 27

PET, fMRI, and fUS have allowed cognitive neuroscien- tists to create images of brain activity while volunteers are engaging in particular cognitive activities. Although technically impressive, these kinds of studies of brain activity and cognition all have what same shortcoming?

Answer 27

They can be used to show a correlation between brain activity and cognitive activity, but they can’t prove that the brain activity caused the cognitive activity. (For example, a brain-imaging technique may show that the cingulate cortex becomes active when volunteers view disturbing photographs, but it can’t prove that the cingulate activity causes the emotional experience—there are many other explanations.)

Question 28

Describe Transcranial magnetic stimulation (TMS).

Answer 28

- a technique that can be used to turn off an area of human cortex by creating a magnetic field under a coil positioned next to the skull. The magnetic stimulation temporarily turns off part of the brain while the effects of the disruption on cognition and behavior are assessed.

Question 29

Describe Transcranial electrical stimulation (tES).

Answer 29

- 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. The electrical stimulation temporarily increases activity in part of the brain while the effects of the stimulation on cognition and behavior are assessed. However, there is conflicting evidence about whether tES has beneficial effects on cognition; some studies have even reported detrimental effects.

Question 30

Describe Transcranial ultrasound stimulation (tUS).

Answer 30

- is a technique that, like tES and TMS, can be used to activate particular brain structures. However, unlike tES and TMS, which can only be used to stimulate cortical structures, tUS can also be used to activate subcortical structures. -To activate a brain structure using tUS, multiple sources of low-amplitude ultrasonic sound waves are placed around the head of the individual. Then, each of those sound sources is directed at the target brain structure. When the ultrasonic sound waves from each of those sources reach the target structure they sum together, such that the amplitude of the sound waves at the target brain structure is sufficiently large to stimulate activity in the cells there. The tUS technique can also be used to make small permanent lesions to a brain structure. The procedure is the same as that for stimulation via tUS, except that the amplitude of each ultrasound source is larger, leading to a larger amplitude waveform that is sufficient to create a small (e.g., the size of a grain of rice) permanent lesion. This tUS-based lesion method has been used to treat several conditions (e.g., lesioning a thalamic nucleus to treat essential tremor)—all without having to make an incision.

Question 31

What are psychophysiological recording methods?

Answer 31

Methods of recording physiological activity from the surface of the human body.

Question 32

Describe SCALP ELECTROENCEPHALOGRAPHY (EEG).

Answer 32

- a measure of the gross electrical activity of the brain. It is recorded through large electrodes by a device called an electroencephalograph (EEG machine), and the technique is called electroencephalography. In EEG studies of human participants, each channel of EEG activity is usually recorded from disk-shaped electrodes, about half the size of a dime, which are attached to the scalp. - The scalp EEG signal reflects the sum of electrical events throughout the head. These events include action potentials and postsynaptic potentials as well as electrical signals from the skin, muscles, blood, and eyes. -Thus, 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 consciousness or particular types of cerebral pathology (e.g., epilepsy). For example, alpha waves are regular, 8- to 12-per-second, high-amplitude waves that are associated with relaxed wakefulness.

Question 33

Why is it usual to record EEG activity from many sites simultaneously?

Answer 33

Because EEG signals decrease in amplitude as they spread from their source, a comparison of signals recorded from various sites on the scalp can sometimes indicate the origin of particular waves.

Question 34

Psychophysiologists are often more interested in the EEG waves that accompany certain psycholog- ical events than in the background EEG signal. These accompanying EEG waves are generally referred to as _____________________.

Answer 34

event-related potentials (ERPs).

Question 35

One commonly studied type of event-related potential is the sensory evoked potential— the change in the cortical EEG signal elicited by the momentary presentation of a sensory stimulus. The cortical EEG that follows a sensory stimulus has two components: the response to the stimulus (the signal) and the ongoing background EEG activity (the noise). Is the signal or the noise of greater interest to psychophysiologists?

Answer 35

The signal is the part of any recording that is of interest; the noise is the part that isn’t. The problem in recording sensory evoked potentials is that the noise of the background EEG is often so great that the sensory evoked potential is masked. Measuring a sensory evoked potential can be like detect- ing a whisper at a rock concert.

Question 36

What is a method used to reduce the noise of the background EEG?

Answer 36

Signal averaging. The analysis of average evoked potentials (AEPs) focuses on the various waves in the averaged signal. Each wave is characterized by its direction, positive or negative, and by its latency. For example, the P300 wave is the positive wave that occurs about 300 milliseconds after a momentary stimulus that has meaning for the participant (e.g., a stimulus to which the participant must respond). In contrast, the portions of an evoked potential recorded in the first few milliseconds after a stimulus are not influenced by the meaning of the stimulus for the participant. These small waves are called far-field potentials because, although they are recorded from the scalp, they originate far away in the sensory nuclei of the brain stem.

Question 37

Describe magnetoencephalography (MEG).

Answer 37

- measures changes in magnetic fields on the surface of the scalp that are produced by changes in underlying patterns of neural activity. Because the magnetic signals induced by neural activity are so small, only those induced near the surface of the brain can be recorded from the scalp

Question 38

MEG has what two major advantages over EEG? .

Answer 38

It has much better spatial resolution than EEG (it can localize changes in electrical activity in the cortex with greater precision). MEG can be used to localize sub-cortical activity with greater reliability than EEG.

Question 39

True or False? Each muscle fiber contracts in an all-or-none fashion when activated by the motor neuron that innervates it.

Answer 39

True. At any given time, a few fibers in each resting muscle are likely to be contracting, thus maintaining the overall tone (tension) of the muscle. Movement results when a large number of fibers contract at the same time. In everyday language, anxious people are commonly referred to as “tense.” This usage acknowledges the fact that anxious or otherwise aroused individuals typically display high resting levels of tension in their muscles. This is why psychophysiologists are interested in this measure; they use it as an indicator of psychological arousal.

Question 40

Describe Electromyography.

Answer 40

is the usual procedure for measuring muscle tension. The resulting record is called an electromyogram (EMG). EMG activity is usually recorded between two electrodes taped to the surface of the skin over the muscle of interest. The main correlate of an increase in muscle contraction is an increase in the amplitude of the raw EMG signal, which reflects the number of muscle fibers contracting at any one time.

Question 41

Describe electrooculography.

Answer 41

- the electrophysiological technique for recording eye movements. The resulting record is called an electrooculogram (EOG). -Electrooculography is based on the fact that a steady potential difference exists between the front (positive) and back (negative) of the eyeball. Because of this steady potential, when the eye moves, a change in the electrical potential between electrodes placed around the eye can be recorded. -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 vertical movements.

Question 42

What are two psychophysiological measures of somatic nervous system activity?

Answer 42

Electromyography is the usual procedure for measuring muscle tension. The electrophysiological technique for recording eye movements is called electrooculography.

Question 43

What are two psychophysiological measures of autonomic nervous system activity?

Answer 43

Skin conductance & Cardiovascular activity.

Question 44

Describe skin conductance level (SCL) and the skin conductance response (SCR).

Answer 44

- The two most commonly employed indexes of electrodermal activity - Emotional thoughts and experiences are associated with increases in the ability of the skin to conduct electricity. -The SCL is a measure of the background level of skin conductance that is associated with a particular situation, whereas the SCR is a measure of the transient changes in skin conductance that are associated with discrete experiences. -there is considerable evidence implicating the sweat glands in skin conductance changes. -the main function of sweat glands is to cool the body, but these glands tend to become active in emotional situations, causing the release of sweat that in turn increases the electrical conductivity of the skin.

Question 45

The cardiovascular system has what two parts?

Answer 45

the blood vessels and the heart. (It is a system for distributing oxygen and nutrients to the tissues of the body, removing metabolic wastes, and transmitting chemical messages.)

Question 46

What are 3 measures of cardiovascular activity that are frequently employed in psychophysiological research?

Answer 46

1) heart rate, 2) arterial blood pressure, and 3) local blood volume.

Question 47

How is heart rate measured?

Answer 47

The electrical signal associated with each heartbeat can be recorded through electrodes placed on the chest. The recording is called an electrocardiogram (abbreviated either ECG or EKG, from the original German). The average resting heart rate of a healthy adult is about 70 beats per minute, but it increases abruptly at the sound, or thought, of a dental drill.

Question 48

How is blood pressure measured?

Answer 48

Two independent measurements: a measurement of the peak pressure during the periods of heart contraction (the systoles), and a measurement of the minimum pressure during the periods of relaxation, (the diastoles). It's expressed as a ratio of systolic over diastolic blood pressure in millimeters of mercury (mmHg). The normal resting blood pressure for an adult is about 130/70 mmHg. A chronic blood pressure of more than 140/90 mmHg is viewed as a serious health hazard and is called hypertension.

Question 49

What is the device called that measures blood pressure?

Answer 49

a sphygmomanometer (sphygmos means “pulse”).

Question 50

How is blood volume measured?

Answer 50

-Plethysmography refers to the various techniques for measuring changes in the volume of blood in a particular part of the body (plethysmos means “an enlargement”). -One method of measuring these changes is to record the volume of the target tissue by wrapping a strain gauge around it. -Another method is to shine a light through the tissue under investigation and to measure the amount of light absorbed by it. The more blood there is in a structure, the more light it will absorb.

Question 51

What is Stereotaxic surgery?

Answer 51

The means by which experimental devices are precisely positioned in the depths of the brain. Two things are required in stereotaxic surgery: an atlas to provide directions to the target site and an instrument for getting there.

Question 52

Describe the process of stereotaxic surgery.

Answer 52

The stereotaxic atlas is used locate brain structures. In stereotaxic atlases, all distances are given in millimeters from a designated reference point. In most rat atlases, the reference point is bregma—the point on the top of the skull where two of the major sutures (seams in the skull) intersect. The stereotaxic instrument has two parts: a head holder, which firmly holds each subject’s brain in the prescribed position and orientation; and an electrode holder, which holds the device to be inserted. A system of precision gears allows the electrode holder to be moved in three dimensions: anterior–posterior, dorsal–ventral, and lateral–medial. 1) The stereotaxic atlas indicates that the amygdala target site is 5 mm ventral. This page of the atlas represents a frontal section that is 2.8 mm posterior to bregma. 2) A hole is drilled 2.8 mm posterior to bregma and 4.5 mm lateral to it. Then, the electrode holder is positioned over the hole, and the electrode is lowered 8.5 mm through the hole (i.e., 8.5 mm ventral). 3) The electrode is anchored to the skull with several stainless steel screws and dental acrylic that is allowed to harden around the electrode connector.

Question 53

Describe ASPIRATION LESIONS.

Answer 53

The cortical tissue is drawn off by suction through a fine-tipped handheld glass pipette. Because the underlying white matter is slightly more resistant to suction than the cortical tissue itself, a skilled surgeon can delicately peel off the layers of cortical tis- sue from the surface of the brain, leaving the underlying white matter and major blood vessels undamaged.

Question 54

Describe Radio Frequency Lesions.

Answer 54

Small subcortical lesions are commonly made by passing radio-frequency current (high-frequency current) through the target tissue from the tip of a stereotaxically positioned electrode. The heat from the current destroys the tissue. The size and shape of the lesion are determined by the duration and intensity of the current and the configuration of the electrode tip.

Question 55

Describe knife cuts.

Answer 55

Sectioning (cutting) is used to eliminate conduction in a nerve or tract. A tiny, well-placed cut can unambiguously accomplish this task without producing extensive damage to surrounding tissue.

Question 56

Describe reversible lesions.

Answer 56

Methods for temporarily eliminating the activity in a particular area of the brain while tests are being conducted. The advantage of reversible lesions is that the same subjects can be repeatedly tested in both the lesion and control conditions. The two most common methods of producing a reversible lesion are by temporarily cooling the target structure or by injecting an anesthetic (e.g., lidocaine) into it.

Question 57

Why it is important to be cautious when interpreting the effects of lesions?

Answer 57

Because the structures of the brain are small, convoluted, and tightly packed together, even a highly skilled surgeon cannot completely destroy a structure without producing significant damage to adjacent structures. There is, however, an unfortunate tendency to lose sight of this fact. For example, a lesion that leaves major portions of the amygdala intact and damages an assortment of neighboring structures comes to be thought of simplistically as an amygdala lesion. Such an apparently harmless abstraction can be misleading in two ways. If you believe that all lesions referred to as “amygdala lesions” include damage to no other brain structure, you may incorrectly attribute all of their behavioral effects to amygdala damage; conversely, if you believe that all lesions referred to as “amygdala lesions” include the entire amygdala, you may incorrectly conclude that the amygdala does not participate in behaviors uninfluenced by the lesion.

Question 58

Describe bilateral and unilateral lesions.

Answer 58

As a general principle—but one with several notable exceptions—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 bilateral, rather than unilateral, lesions.

Question 59

Describe the technique of electrical brain stimulation.

Answer 59

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 bipolar electrode—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. Because electrical stimulation of the brain is an invasive procedure, its use is usually limited to nonhumans. However, sometimes the brains of conscious human patients are stimulated for therapeutic reasons.

Question 60

Why is electrical stimulation of the brain is an important biopsyhological research tool?

Answer 60

it often has behavioral effects, usually opposite to those produced by a lesion to the same site. It can elicit a number of behavioral sequences, including eating, drinking, attacking, copulating, and sleeping. The particular behavioral response elicited depends on the location of the electrode tip, the parameters of the current, and the test environment in which the stimulation is administered.

Question 61

Describe INTRACELLULAR UNIT RECORDING.

Answer 61

- provides a moment-by-moment record of the graded fluctuations in one neuron’s membrane potential. -Most experiments using this recording procedure are performed on chemically immobilized animals because it is difficult to keep the tip of a microelectrode positioned inside a neuron of a freely moving animal.

Question 62

Describe extracellular recording.

Answer 62

- it is possible to record the activity 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. Accordingly, extracellular unit recording provides a record of the firing of a neuron but no information about the neuron’s membrane potential. -it is now possible to simultaneously record extracellular signals from up to about 1,000 neurons by analyzing the correlations among the signals picked up through several different electrodes implanted in the same general area .

Question 63

Describe multiple-unit recording.

Answer 63

- the electrode tip is much larger than that of a micro- electrode; 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. A multiple-unit recording is a graph of the total number of recorded action potentials per unit of time (e.g., per 0.1 second).

Question 64

Describe INVASIVE EEG RECORDING.

Answer 64

In nonhuman animals, and sometimes in human patients, EEG signals can be recorded through implanted electrodes rather than through scalp electrodes. In nonhuman animals, cortical EEG signals are frequently recorded through stainless steel skull screws, whereas subcortical EEG signals are typically recorded through implanted wire electrodes.

Question 65

What is the major research strategy of psychopharmacology? is to administer drugs that either increase or decrease the effects of particular neurotransmitters and to observe the behavioral consequences.

Answer 65

To administer drugs that either increase or decrease the effects of particular neurotransmitters and to observe the behavioral consequences.

Question 66

Describe the various methods of drug administration.

Answer 66

(1) they are fed to the subject; (2) they are injected through a tube into the stomach (intragastrically); or (3) they are injected hypodermically into the peritoneal cavity of the abdomen (intraperitoneally, IP), into a large muscle (intramuscularly, IM), into the fatty tissue beneath the skin (subcutaneously, SC), or into a large surface vein (intravenously, IV).

Question 67

What is a problem with peripheral routes of drug administration?

Answer 67

Many drugs do not readily pass through the blood–brain barrier. To overcome this problem, drugs can be administered in small amounts through a fine, hollow tube, called a cannula, that has been stereotaxically implanted in the brain.

Question 68

Describe the method of selective neurotoxic lesions.

Answer 68

In some cases, more selective lesions by injecting neurotoxins (neural poisons) that have an affinity for certain components of the nervous system. There are many selective neurotoxins. When either kainic acid or ibotenic acid is administered by microinjection, it is preferentially taken up by cell bodies at the tip of the cannula and destroys those neurons, while leaving neurons with axons passing through the area largely unscathed. Another selective neurotoxin that has been widely used is 6-hydroxydopamine (6-OHDA). It is taken up by only those neu- rons that release the neurotransmitter nor- epinephrine or dopamine, and it leaves other neurons at the injection site undamaged.

Question 69

Describe two techniques for measuring chemical activity in the brain.

Answer 69

2-deoxyglucose (2-DG) 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 metabolize it. Then the subject is killed, and its brain is removed and sliced. The slices are then subjected to autoradiography: They are coated with a photographic emulsion, stored in the dark for a few days, and then developed much like film. Areas of the brain that absorbed high levels of radioactive 2-DG during the test appear as black spots on the slides. The density of the spots in various regions of the brain can then be color-coded. Cerebral dialysis - is a method of measuring the extracellular concentration of specific neurochemicals in behaving animals (most other techniques for measuring neurochemicals require that the subjects be killed so that tissue can be extracted). Cerebral dialysis involves implanting a fine tube with a short semipermeable section into the brain. The semi- permeable section is positioned in the brain structure of interest so that extracellular chemicals from the structure will diffuse into the tube. Once in the tube, they can be collected for freezing, storage, and later analysis; or they can be carried in solution directly to a chromatograph (a device for measuring the chemical constituents of liquids or gases).

Question 70

What are two techniques for locating particular neurotransmitters or receptors in the brain?

Answer 70

immunocytochemistry and in situ hybridization. Each involves exposing brain slices to a labeled ligand of the molecule under investigation (the ligand of a molecule is another molecule that binds to it).

Question 71

Describe immunocytochemistry.

Answer 71

- a procedure for locating particular neuroproteins in the brain by labeling their antibodies with a dye or radioactive element and then exposing slices of brain tissue to the labeled antibodies. Regions of dye or radioactivity accumulation in the brain slices mark the locations of the target neuroprotein. When a foreign protein (an antigen) is injected into an animal, the animal’s body creates antibodies that bind to it and help the body remove or destroy it; this is known as the body’s immune reaction. Neurochemists have created stocks of antibodies for the brain’s peptide neurotransmitters (neuropeptides) and their receptors.

Question 72

Describe in situ hybridization.

Answer 72

- This technique takes advantage of the fact that all peptides and proteins are transcribed from sequences of nucleotide bases on strands of messenger RNA (mRNA). The nucleotide base sequences that direct the synthesis of many neuroproteins have been identified, and hybrid strands of mRNA with the complementary base sequences have been artificially created. Steps: 1) hybrid RNA strands with the base sequence complementary to that of the mRNA that directs the synthesis of the target neuroprotein are obtained. 2) the hybrid RNA strands are labeled with a dye or radioactive element. 3) The brain slices are exposed to the labeled hybrid RNA strands; they bind to the complementary mRNA strands, marking the location of neurons that release the target neuroprotein.

Question 73

There are three categories of genetic testing methods?

Answer 73

(1) gene knockout techniques, (2) gene knockin techniques, and (3) gene editing techniques.

Question 74

Explain the gene knockout technique by describing an experiment that employed the technique.

Answer 74

- Procedures for creating organisms that lack a particular gene under investigation. Mice that are the products of gene knockout techniques are referred to as knockout mice. -Researchers used melanopsin knockout mice (mice in whom the gene for the synthesis of melanopsin has been deleted) to study the role of melanopsin in regulating the light–dark cycles that control circadian (about 24 hours) rhythms of bodily function—for example, daily cycles of sleep, eating, and body temperature. -Melanopsin is a protein found in some neurons in the mammalian retina, and it had been implicated in the control of circadian rhythms by light. Knockout of the gene for synthesizing melanopsin impaired, but did not eliminate, the ability of mice to adjust their circadian rhythms in response to changes in the light–dark cycle. Thus, melanopsin appears to contribute to the control of circadian rhythms by light, but it is not the only factor.

Question 75

Explain the gene knockin technique by describing an experiment that employed the technique.

Answer 75

- It is now possible to replace one gene with another or add a gene that doesn’t exist in an organism. Pathological genes from human cells can be inserted in other animals such as mice—mice that contain the genetic material of another species are called transgenic mice. - Researchers created transgenic mice by inserting a defective human gene that had been found to be associated with schizophrenia in a Scottish family with a particularly high incidence of the condition. -The transgenic mice displayed a variety of cerebral abnormalities (e.g., reduced cerebral cortex and enlarged ventricles) and atypical behaviors reminiscent of human schizophrenia. -Treating neurological disease by replacing faulty genes in patients suffering from genetic disorders is an exciting, but as yet unrealized, goal.

Question 76

Describe how modern gene editing techniques, such as the CRISP-Cas9 method, can provide better ways of assessing the role of a gene in behavior.

Answer 76

-Each behavior is controlled by many genes inter- acting with one another and with experience over the course of development (through epigenetic mechanisms). As a means of controlling for the interaction of genes with experience, many researchers now use modern gene editing techniques. These new gene editing techniques allow researchers to edit genes at a particular time during development. -CRISPR/Cas9 method - Cas9 (a protein) is linked to a strand of RNA called the guide-RNA. The guide-RNA is made up of a sequence of nucleotide bases that are complementary to one or more strands of DNA. Once the guide-RNA and Cas9 are linked, it can be integrated into a virus. The virus can then be injected into an animal—either peripherally if one wants to edit the genome of the whole organism, or intracranially into a specific brain region if one wants to observe the focal effects of editing a gene in cells in that brain region. Once the virus enters a cell, and the guide-RNA lines up with a complementary strand of DNA in the organ- ism, Cas9 can either inhibit or activate the genes through various mechanisms. Furthermore, Cas9 can be regu- lated in various ways so that a researcher can control the effects of Cas9 on gene expression; thus, a researcher can reversibly alter the expression of a gene (or set of genes) in a particular brain region and examine the effects on behavior. Cas9 can also be used to alter an organism’s epigenome.

Question 77

Explain how green fluorescent protein has been used as a research tool in the neurosciences.

Answer 77

-Green fluorescent protein (GFP) is a protein that exhibits bright green fluorescence when exposed to blue light. (First isolated from a species of jellyfish) -GFP's gene was identified and cloned. The general strategy is to activate the GFP gene in only the particular cells under inves-tigation so that they can be readily visualized by 1) by inserting the GFP gene in only the target cells or 2) by introducing the GFP gene in all cells of the subject but expressing the gene in only the target cells. -to visualize neurons they introduced the GFP gene into a small transparent roundworm, in an area of its chromosomes that controls the development of touch receptor neurons. - making minor alterations to the GFP gene resulted in the synthesis of proteins that fluoresced in different colors. The mutated genes for cyan, yellow, and blue fluorescent proteins into the genomes of developing mice in such a way that they were expressed in developing neurons. Because each neuron was labeled with its own distinctive color, the pathways of neural axons could be traced to their destinations through the cellular morass. This technique has been dubbed brainbow .

Question 78

In addition to making brainbows, what else have fluorescent proteins have allowed researchers to do?

Answer 78

(1) label specific neurotransmitters so their activity can be observed (2) label synaptic vesicle proteins in order to observe the fusion of synaptic vesicles with the presynaptic membrane (3) visualize postsynaptic potentials (see Chapter 4) by using fluorescent proteins that light up during membrane hyperpolarizations or depolarizations, and (4) observe the binding of neurotransmitters to receptors by creating receptors that light up when they bind their transmitter

Question 79

Explain how opsins have been used as a research tool in the neurosciences.

Answer 79

Opsins are 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. Depending on the particular opsin, light can either hyperpolarize or depolarize the cell membrane they are embedded in. -The gene was identified and rendered into a form that was expressible within a mammalian cell, then they inserted the gene into into particular types of neurons to hyperpolarize or depolarize neurons. This is called 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 only specific neurons to either be increased or suppressed.

Question 80

Go back to page 140-141 and do the abbreviation fill-in-the-blank task.

Question 81

A single set of procedures developed for the investigation of a particular behavioral phenomenon is commonly referred to as a _________________.

Answer 81

behavioral paradigm. Each behavioral paradigm normally comprises a method for producing the behavioral phenomenon under investigation and a method for objectively measuring it.

Question 82

A patient suspected of suffering from some sort of nervous system dysfunction is usually referred to a __________, who assesses simple sensory and motor functions. More subtle changes in perceptual, emotional, motivational, or cognitive functions are the domain of the ______________.

Answer 82

neurologist neuropsychologist.

Question 83

Because neuropsychological testing is so time consuming, it is typically prescribed for only a small portion of brain-damaged patients. Why is this unfortunate?

Answer 83

the results of neuropsychological testing can help brain-damaged patients in three important ways: (1) by assisting in the diagnosis of neural disorders, particularly in cases in which brain imaging, EEG, and neurological testing have proved equivocal; ( 2) by serving as a basis for counseling and caring for the patients; and (3) by providing a basis for objectively evaluating the effectiveness of a treatment or the seriousness of its side effects.

Question 83

Describe three approaches to neuropsychological testing.

Answer 83

1) Single-Test Approach - the goal of these early tests was to discriminate between patients with psychological problems resulting from structural brain damage and those with psychological problems resulting from functional, rather than structural, changes to the brain. This approach proved unsuccessful, in large part because no single test could be developed that would be sensitive to all the varied and complex psychological symptoms that could potentially occur in a brain-damaged patient. 2) STANDARDIZED-TEST-BATTERY APPROACH - to identify brain-damaged patients—but the testing involved standardized batteries (sets) of tests rather than a single test such as the Halstead-Reitan. The scores on each test are added together to form a single aggregate score. An aggregate score below the designated cutoff leads to a diagnosis of brain damage. Only marginally successful; standardized test batteries discriminate effectively between neurological patients and healthy individuals, but they are not so good at discriminating between neurological patients and psychiatric patients. 3) THE CUSTOMIZED-TEST-BATTERY APPROACH - begins with a common battery of tests to provide an indication of the general nature of the symptoms. Then, a series of tests customized to each patient in an effort to characterize in more detail the general symptoms revealed by the common battery.

Question 84

Describe those tests that are often administered as part of an INITIAL common neuropsychological test battery.

Answer 84

Intelligence - IQ is a poor measure of brain damage, but these tests are typically still administered. Most popular: Wechsler Adult Intelligence Scale (WAIS). Memory - WAIS assesses memory for general knowledge the digit span subtest which are the 2 LEAST likely forms of memory to be disrupted by brain damage. Language - assessed on WAIS or using a token test ("touch a red square and then the green circle"). Language Lateralization - The sodium amytal test involves injecting the anesthetic sodium amytal into either the left or right carotid artery in the neck. This temporarily anesthetizes the ipsilateral (same-side) hemisphere while leaving the contralateral (opposite-side) hemisphere largely unaffected. Tests of language function are quickly administered while the ipsilateral hemisphere is anesthetized. When the injection is on the side dominant for language, the patient is completely mute for about 2 minutes. When the injection is on the non- dominant side, there are only a few minor speech problems. OTHER METHOD: dichotic listening test - sequences of spoken digits are presented to volunteers through headphones. Three digits are presented to one ear at the same time that three different digits are presented to the other ear. Then, they are asked to report as many of the six digits as they can. Patients correctly report more of the digits heard by the ear contralateral to their dominant hemisphere for language, as determined by the sodium amytal test.

Question 85

Describe tests that might be used by a neuropsychologist to investigate in more depth general problems revealed by a common neuropsychological test battery.

Answer 85

Memory - (1) short-term memory, long-term memory, or both? (2) Are any deficits in long-term memory anterograde (affecting the retention of things learned after the damage), retrograde (affecting the retention of things learned before the damage), or both? (3) Do any deficits in long-term memory involve semantic memory (memory for knowledge of the world) or episodic memory (memory for personal experiences)? (4) Are any deficits in long-term memory deficits of explicit memory (memories of which the patient is aware and can thus express verbally), implicit memory (memories demonstrated by the improved performance of the patient without the patient being conscious of them), or both? Common test: Repetition priming tests - shown words, not asked to memorize, then later shown word fragments of intial words.

Question 86

Many amnesic patients display severe deficits in _______ memory with no deficits at all in _________ memory

Answer 86

explicit implicit (For example, if “purple” had been in the initial test, “pu_p_ _” could be one of the test word fragments. Amnesic patients often complete the fragments as accurately as healthy control subjects. But—and this is the really important part—they often have no conscious memory of any of the words in the initial list or even of ever having seen the list. In other words, they display good implicit memory of experiences without explicit memories of them.)

Question 87

Some dyslexic patients (those with reading problems) remember the rules of pronunciation but have difficulties pronouncing words that do not follow these rules, words such as come and tongue, whose pronunciation must be remembered. Other dyslexic patients pronounce simple familiar words based on memory but have lost the ability to apply the rules of pronunciation—they cannot pronounce nonwords such as trapple or fleeming.

Question 88

What is cognitive neuroscience?

Answer 88

A division of biopsychology that focuses on understanding cognition.

Question 89

What are 2 key assumptions that are common in cognitive neuroscience?

Answer 89

1) each complex cognitive process results from the combined activity of simple cognitive processes called constituent cognitive processes. 2) each constituent cognitive process is mediated by neural activity within a particular brain region or across a set of brain regions.

Question 90

What is the main goal of cognitive neuroscience?

Answer 90

To identify the parts of the brain that mediate various constituent cognitive processes.

Question 91

Describe the paired-image subtraction technique.

Answer 91

Much of the activity recorded (while having a patient do a word-association task during a PET scan) would be associated with other processes such as seeing the words, reading the words, and speaking. The paired-image subtraction technique was developed to deal with this problem. The paired-image subtraction technique involves obtaining functional brain images during several different cognitive tasks. Ideally, the tasks are designed so that pairs of them differ from each other in terms of only a single constituent cognitive process. Then the brain activity associated with that process can be estimated by subtracting the activity in the image associated with one of the two tasks from the activity in the image associated with the other. Produces a difference image – which illustrates the areas of the brain specifically involved in the constituent cognitive process of forming the word association; the activity associated with fixating on the screen etc.

Question 92

What is the default mode network and what structures that are part of that network?

Answer 92

There is substantial brain activity when humans sit quietly and let their minds wander—this level of activity has been termed the brain’s default mode. Brain structures typically active in the default mode but less active during cognitive or behavioral tasks are collectively referred to as the default mode network, and their pattern of activity is known as the resting state-fMRI (R-fMRI). The default mode network comprises many structures including: medial parietal cortex, lateral parietal cortex, medial prefrontal cortex, and lateral temporal cortex.

Question 93

Explain what a mean difference image is.

Answer 93

Average the images obtained from several volunteers; the resulting mean (averaged) difference image emphasizes areas of activity that are common to many volunteers and de-emphasizes areas of activity that are peculiar to a few of them.

Question 94

Explain the concept of functional connectivity.

Answer 94

How network activity across multiple brain regions is related to a particular cognitive task. To measure FC, a cognitive neuroscientist examines which brain regions have parallel patterns of activity over time. changes in FC with the presentation of a stimulus, or during the performance of a task, they are studying extrinsic FC. This is in contrast to intrinsic FC, which is FC that is present during the R-fMRI. Collectively, the task of characterizing the FC associated with each behavior and cognitive process is known as the study of the functional connectome.

Question 95

What are Species-common behaviors?

Answer 95

Those displayed by virtually all members of a species, or at least by all those of the same age and sex. Commonly studied species-common behaviors include grooming, swimming, eating, drinking, copulating, fighting, and nest building.

Question 96

What are 3 behavioral paradigms used to study species-common behaviors?

Answer 96

open-field test, tests of aggressive and defensive behavior, and tests of sexual behavior.

Question 97

Describe an open-field test.

Answer 97

the subject is placed in a large, barren chamber, and its activity is recorded. They also count the number of boluses (pieces of excrement) that were dropped by an animal during the test. Low activity scores and high bolus counts are frequently used as indicators of fearfulness. Fearful rats are also highly thigmotaxic; that is, they rarely venture away from the walls of the test chamber and rarely engage in such activities as rearing and grooming.

Question 98

What is the colony-intruder paradigm?

Answer 98

Patterns of aggressive and defensive behavior can be observed and measured during combative encounters between the dominant male rat of an established colony and a smaller male intruder.

Question 99

What is the elevated plus maze?

Answer 99

A four-armed, plus-sign-shaped maze typically mounted 50 centimeters above the floor, is a test of defensiveness commonly used to study the anxiolytic (anxiety-reducing) effects of drugs. The measure of defensiveness, or anxiety, is the proportion of time the rats spend in the protected closed arms rather than on the exposed arms.

Question 100

Describe tests of sexual behaviours.

Answer 100

Most attempts focus the copulatory act itself. The male mounts the female from behind and clasps her hindquarters. If the female is receptive, she responds by assuming the posture called lordosis; that is, she sticks her hindquarters in the air, she bends her back in a U, and she deflects her tail to the side. During some mounts, the male inserts his penis into the female’s vagina; this act is called intromission. After intromission, the male dismounts by jumping backward. He then returns a few seconds later to mount and intromit once again. Following about 10 such cycles of mounting, intromitting, and dismounting, the male mounts, intromits, and ejaculates (ejects his sperm). Three common measures of male rat sexual behavior are the number of mounts required to achieve intromission, the number of intromissions required to achieve ejaculation, and the interval between ejaculation and the reinitiation of mounting. The most common measure of female rat sexual behavior is the lordosis quotient (the proportion of mounts that elicit lordosis).

Question 101

Why do learning paradigms play a major role in biopsychological research?

Answer 101

1) learning is a phenomenon of primary interest to psychologists. 2) learning paradigms provide an effective technology for producing and controlling animal behavior. Because animals cannot follow instructions from the experimenter, it is often necessary to train them to behave in a fashion consistent with the goals of the experiment. 3) It is possible to infer much about the sensory, motor, motivational, and cognitive state of an animal from its ability to learn and perform various responses.

Question 102

What is the Pavlovian conditioning paradigm?

Answer 102

The experimenter pairs an initially neutral stimulus called a conditional stimulus (e.g., a tone or a light) with an unconditional stimulus (e.g., meat powder)—a stimulus that elicits an unconditional (reflexive) response (e.g., salivation). As a result of these pairings, the conditional stimulus eventually acquires the capacity, when administered alone, to elicit a conditional response (e.g., salivation)—a response that is often, but not always, similar to the unconditional response.

Question 103

What is the operant conditioning paradigm?

Answer 103

The rate at which a particular voluntary response (such as a lever press) is emitted is increased by reinforcement or decreased by punishment. Ie: The self-stimulation paradigm where animals press a lever to deliver electrical stimulation to particular sites in their own brains; those structures in the brain that support self-stimulation have often been called pleasure centers.

Question 104

What are 4 common seminatural learning paradigms?

Answer 104

Conditioned taste aversion, radial arm maze, Morris water maze, and conditioned defensive burying.

Question 105

Describe conditioned taste aversion.

Answer 105

The avoidance response that develops to tastes of food whose consumption has been followed by illness. Rats receive an emetic (a nausea-inducing drug) after they consume a food with an unfamiliar taste. On the basis of this single conditioning trial, the rats learn to avoid the taste.

Question 106

The discovery of conditioned taste aversion challenged what three widely accepted principles of learning ?

Answer 106

1) It challenged the view that animal conditioning is always a gradual step-by-step process. 2) It showed that temporal contiguity is not essential for conditioning (rats acquire taste aversions even when they do not become ill until several hours after eating). 3) It challenged the principle of equipotentiality—the view that conditioning proceeds in basically the same manner regardless of the particular stimuli and responses under investigation (Rats appear to have evolved to readily learn associations between tastes and illness; it is only with great difficulty that they learn relations between the color of food and nausea or between taste and footshock.)

Question 107

What is the radial arm maze?

Answer 107

an array of arms - radiating from a central starting area. At the end of each arm is a food cup, which may or may not be baited, depending on the purpose of the experiment. Studies the well-developed spatial abilities of rodents. The survival of rats in the wild depends on their ability to navigate quickly and accurately through their environment and to learn which locations in it are likely to contain food and water. After a few days of experience, rats rarely visit unbaited arms at all, and they rarely visit baited arms more than once in the same day—even when control procedures make it impossible for them to recognize odors left during previous visits.

Question 108

What is the Morris water maze?

Answer 108

Tests spatial abilities. The rats are placed in a circular, featureless pool of cool milky water in which they must swim until they discover the escape platform—which is invisible just beneath the surface of the water. Even though the starting point is varied from trial to trial, the rats learn after only a few trials to swim directly to the platform, presumably by using spatial cues from the room as a reference. The Morris water maze is useful for assessing the navigational skills of brain-lesioned or drugged animals.

Question 109

What is conditioned defensive burying?

Answer 109

Rats receive a single aversive stimulus (e.g., a shock, air blast, or noxious odor) from an object mounted on the wall of the chamber just above the floor, which is littered with bedding material. After a single trial, almost every rat learns that the test object is a threat and responds by flinging bedding material at the test object with its head and forepaws. Antianxiety drugs reduce the amount of conditioned defensive burying, and thus the paradigm is used to study the neurochemistry of anxiety.