5- Research Methods in Biopsychology

1. x-ray based techniques

2. radioactivity-based technique

3. magnetic-based technique

three different sorts of methods for

visualizing the living human brain

1. Contrast x-rays

2. Computerized tomography (CT)

two x-ray-based techniques

Contrast x-ray techniques

involve

injecting into one compartment of

the body a substance that absorbs

x-rays either less than or more than

the surrounding tissue.

Cerebral angiography

uses the infusion of a radioopaque

dye into a cerebral artery to visualize

the cerebral circulatory system during x-ray photography

Cerebral angiography

most useful for localizing

vascular damage, but the displacement of blood vessels from

their normal position also can indicate the location of a tumor.

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

Computed tomography (CT)

Provides a 3-D representation of the brain

Positron emission tomography (PET)

first brain-imaging technique

to provide images of brain activity (functional brain

images) rather than images of brain structure

fluorodeoxyglucose (FDG)

injected into the patient’s

carotid artery (an artery of the neck that feeds the ipsilateral

cerebral hemisphere)

Positron emission tomography (PET)

Provides images of brain activity

Positron emission tomography (PET)

Scan is an image of levels of radioactivity in various parts of one horizontal level of the brain

1. Magnetic resonance imaging (MRI)

2. Functional MRI

3. Diffusion tensor imaging

three magnetic-field-based techniques

Magnetic resonance imaging (MRI)

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.

spatial resolution

the ability to detect and represent differences in spatial

location

Functional MRI (fMRI)

produces images representing

the increase in oxygen flow in the blood to active

areas of the brain.

Functional MRI (fMRI)

Provides images of brain structure and activity

Functional MRI (fMRI)

Structure is imaged using waves emitted by hydrogen ions

Functional MRI (fMRI)

Function is imaged using signal created from interaction between oxygen and iron in the blood

blood-oxygen-level-dependent signal

The signal recorded by

fMRI is called the

Diffusion tensor imaging

method of identifying those pathways along which water

molecules rapidly diffuse

1. Transcranial magnetic stimulation (TMS)

2. Transcranial direct current stimulation (tDCS)

two transcranial stimulation techniques

Transcranial magnetic stimulation (TMS)

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

Transcranial magnetic stimulation (TMS)

Provides an experimental probe to alter neural activity

Transcranial magnetic stimulation (TMS)

applies a brief, strong magnetic field that alters neural activity

--Can either activate or “deactivate” brain structures

--Observe changes in behavior

Transcranial direct current stimulation (tDCS)

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

psychophysiological recording methods

methods of recording physiological

activity from the surface of the human body

1. scalp EEG

2. magnetoencephalography

two measures of brain activity

scalp electroencephalogram (EEG)

measure of the gross electrical activity

of the brain

alpha waves

regular, 8- to

12-per-second, high-amplitude waves that are associated

with relaxed wakefulness.

event-related potentials (ERPs)

Psychophysiologists are often

more interested in the EEG waves

that accompany certain psychological

events than in the background

EEG signal. These accompanying

EEG waves are generally referred to

as

sensory evoked potential

the change in the

cortical EEG signal elicited by the

momentary presentation of a sensory

stimulus.

signal averaging

A method used to reduce

the noise of the background EEG

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.

P300 wave

positive wave that occurs about 300 milliseconds

after a momentary stimulus that has meaning for

the subject (e.g., a stimulus to which the subject must respond)

far-field potentials

recorded

from the scalp, they originate far away in the sensory

nuclei of the brain stem

magnetoencephalography (MEG)

A measure of neural activity

•Measures changes in magnetic fields on the surface of the scalp

1. muscle tension

2. eye movement

two psychophysiological measures

of somatic nervous system activity.

Electromyography

usual procedure for measuring

muscle tension

electrooculography

The electrophysiological technique

for recording eye movements

Electromyogram (EMG)  

indicates tension of muscles under the skin

Electrooculogram (EOG) 

indicates changes in electrical potential between the front and back of the eyeball

Skin conductance

Measures of electrodermal activity

skin conductance level (SCL)

is a measure of the background level of skin conductance

that is associated with a particular situation

skin conductance response (SCR)

is a measure of the transient changes in skin conductance

that are associated with discrete experiences.

1. heart rate

2. blood pressure

3. blood volume

Three different measures of cardiovascular activity

are frequently employed in psychophysiological research:

cardiovascular activity

Often used to link physiological changes with emotional state

electrocardiogram (ECG/EKG)

The electrical signal associated with each

heartbeat can be recorded through electrodes placed on the

chest.

70 bpm

average resting heart rate of a

healthy adult

systole

a measurement of

the peak pressure during the periods of heart contraction

diastole

a measurement of the minimum pressure during

the periods of relaxation

130/70 mmHg

normal resting

blood pressure for an adult

hypertension

A chronic

blood pressure of more than 140/90 mmHg is viewed as a

serious health hazard and is called

sphygmomanometer

crude device composed of a hollow

cuff, a rubber bulb for inflating it, and a pressure gauge for

measuring the pressure in the cuff

Plethysmography

refers to the various techniques

for measuring changes in the volume of blood in a particular

part of the body

Stereotaxic surgery

is the means by

which experimental devices are precisely positioned in the

depths of the brain

stereotaxic atlas

is used to locate brain structures in

much the same way that a geographic atlas is used to locate

geographic landmarks

bregma

In some rat atlases, the reference

point is - —the point on the top of the skull where

two of the major sutures (seams in the skull) intersect.

head holder

which firmly holds each subject’s brain in the prescribed

position and orientation

electrode holder

which holds

the device to be inserted

lesion methods

In those methods, a part of the brain is

damaged, destroyed, or inactivated; then

the behavior of the subject is carefully

assessed in an effort to determine the

functions of the lesioned structure

Aspiration lesions

When a lesion

is to be made in an area of cortical tissue

that is accessible to the eyes and

instruments of the surgeon

Radio-frequency lesions

Small

subcortical lesions are commonly made

by passing radio-frequency current (highfrequency

current) through the target

tissue from the tip of a stereotaxically positioned

electrode.

Sectioning (cutting)

is used to eliminate

conduction in a nerve or tract

Reversible lesions

methods for temporarily eliminating the activity in a particular

area of the brain while tests are being conducted.

cryogenic blockade

can be produced by cooling the

target structure or by injecting an anesthetic

unilateral lesions

lesions restricted

to one half of the brain

bilateral lesions

lesions involving both sides

of the brain

Electrical stimulation

may be used to “activate” a structure

1. intracellular unit recording

2. extracellular unit recording

3. multiple-unit recording

4. invasive EEG recording

four invasive electrophysiological

recording methods:

intracellular unit recording

invasive electrophysiological recording method that records the membrane potential of a neuron

Extracellular unit recording

records the electrical

disturbance that is created each time an adjacent neuron

fires.

Multiple-unit recording

invasive electrophysiological recording method that records the firing of many neurons

Invasive EEG recording

A large implanted electrode picks up general

changes in electrical brain activity

1. fed to the subject

2. intragastrically

3. intraperitoneally (IP),intramuscularly (IM), subcutaneously (SC), or intravenously (IV)

routes of drug administration

neurotoxins

it is

possible to make more selective lesions by injecting -

(neural poisons) that have an affinity for certain

components of the nervous system.

6-hydroxydopamine (6-OHDA)

It is taken up by only

those neurons that release the neurotransmitter norepinephrine

or dopamine, and it leaves other neurons at the injection

site undamaged.

1. 2-deoxyglucose (2-DG) technique

2. Cerebral dialysis

two techniques for measuring

chemical activity in the brain.

2-deoxyglucose (2-DG) technique

entails placing an animal that has been injected

with radioactive - in a test situation in which it

engages in an activity of interest

2-deoxyglucose (2-DG) technique

Use autoradiography to see where radioactivity accumulates in brain slices

autoradiography

they are coated with a photographic emulsion,

stored in the dark for a few days, and then developed much

like film.

Cerebral dialysis

measures extracellular concentration of specific chemicals in live animals

1. immunocytochemistry

2. In situ hybridization 

two techniques for locating particular

neurotransmitters or receptors in the brain

Immunocytochemistry 

based on the binding of labeled protein-specific antibodies

Immune response

antibodies created that bind and remove/destroy antigens (foreign proteins)

Immunocytochemistry 

is 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

in situ hybridization

This technique takes advantage of

the fact that all peptides and proteins

are transcribed from sequences of

nucleotide bases on strands of messenger

RNA

in situ hybridization

uses labeled RNA to locate neurons with complementary mRNA

Gene knockout techniques

Subjects missing a given gene can provide insight into what the gene controls

Gene knockout techniques

are procedures for creating organisms that lack a

particular gene under investigation

Gene replacement technique

Insert pathological human genes in mice

Green fluorescent protein (GFP) 

exhibits bright green florescence when exposed to blue light

Green fluorescent protein (GFP) 

These - genes can be inserted into DNA of neurons—color can then be viewed when targeted neuronal genes are expressed

Brainbow

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.

Opsins

are light-sensitive ion channels that are found

in the cell membranes of certain bacteria and algae

optogenetics

effect, by inserting an opsin gene into a particular type of

neuron, a neuroscientist could use light to hyperpolarize

or depolarize neurons

behavioral paradigm

single set of procedures developed for the investigation

of a particular behavioral phenomenon is commonly

referred to as a -

Neurologist

patient suspected of suffering from some sort of nervous

system dysfunction is usually referred to a - who

assesses simple sensory and motor functions.

Neuropsychologist

More subtle changes in perceptual, emotional,

motivational, or cognitive functions

are the domain of the

Single-test approach

Used to differentiate brain damage from functional (psychological) causes

Standardized-test-battery approach

involved standardized batteries (sets) of tests rather than a single test