Download Document

Chapter 5
Methods and Strategies of
Research
This multimedia product and its contents are protected under copyright law.
The following are prohibited by law:
• any public performance or display, including transmission of any image over a network;
•preparation of any derivative work, including the extraction, in whole or in part, of any images;
•any rental, lease, or lending of the program.
1
Copyright © 2004 Allyn and Bacon
Experimental Ablation
 Evaluating the Behavioral Effects of Brain Damage:
 Experimental ablation:
• The removal or destruction of a portion of the
brain of a laboratory animal; presumably, the
functions that can no longer be performed are the
ones the region previously controlled.
 Lesion study:
• A synonym for experimental ablation.
2
Copyright © 2004 Allyn and Bacon
Experimental Ablation
 Producing Brain Lesions:
 Excitotoxic lesion:
• A brain lesion produced by intracerebral injection
of an excitatory amino acid, such as kainic acid.
 6-hydroxydopamine (6-HD):
• A chemical that is selectively taken up by axons
and terminal buttons of noradrenergic or
dopaminergic neurons and acts as a poison,
damaging or killing them.
3
Copyright © 2004 Allyn and Bacon
Experimental Ablation
 Producing Brain Lesions:
 Sham lesion:
• A “placebo” procedure that duplicates all of the
steps of producing a brain lesion except for the
one that actually causes the brain damage.
4
Copyright © 2004 Allyn and Bacon
Experimental Ablation
 Stereotaxic Surgery
 Stereotaxic Surgery:
• Brain surgery using a stereotaxic apparatus to
position an electrode or cannula in a specified
position of the brain.
 Bregma:
• The junction of the sagittal and coronal sutures of
the skull, often used as a reference point for
stereotaxic brain surgery.
5
Copyright © 2004 Allyn and Bacon
Experimental Ablation
 The Stereotaxic Atlas
 Stereotaxic atlas:
• A collection of drawings of sections of the brain of
a particular animal with measurements that
provide coordinates for the stereotaxic surgery.
 Stereotaxic apparatus:
• A device that permits a surgeon to position an
electrode of cannula into a specific part of the
brain.
6
Copyright © 2004 Allyn and Bacon
Histological Methods
 Fixation and Sectioning
 Fixative:
• A chemical such as formalin; used to prepare and
preserve body tissue.
 Formalin:
• The aqueous solution of formaldehyde gas; the
most commonly used tissue fixative.
7
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Histological Methods
 Fixation and Sectioning
 Perfusion:
• The process by which an animal’s blood is
replaced by a fluid such as a saline solution or a
fixative in preparing the brain for histological
examination.
 Microtome:
• An instrument that produces very thin slices of
body tissue.
13
Copyright © 2004 Allyn and Bacon
Tracing Neural Connections
 Tracing Efferent Axons
 Anterograde labeling method:
• A histological method that labels the axons and
terminal buttons of neurons whose cell bodies
are located in a particular region.
 PHLA-L:
• Phaseolus vulgaris leukoagglutinin; a protein
derived from kidney beans and used as an
anterograde tracer; taken up by dendrites and
cell bodies and carried to the ends the axons.
14
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Tracing Neural Connections
 Tracing Efferent Axons
 Immunocytochemical method:
• A histological method that uses radioactive
antibodies or antibodies bound with a dye
molecule to indicate the presence of particular
proteins of peptides.
16
Copyright © 2004 Allyn and Bacon
Tracing Neural Connections
 Tracing Afferent Axons
 Retrograde labeling method:
• A histological method that labels cell bodies that
give rise to the terminal buttons that form
synapses with cells in a particular region.
 Fluorogold:
• A dye that serves as a retrograde label; taken up
by the terminal buttons and carried back to the
cell bodies.
17
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Study of the Living Human Brain
 Computerized tomography (CT):
• The use of a device that employed a computer to
analyze data obtained by a scanning beam of Xrays to produce a two dimensional picture of a
slice through the body.
 Magnetic resonance imaging (MRI):
• A technique whereby the interior of the body can
be accurately imaged; involves the interaction
between radio waves and a strong magnetic
field.
19
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Recording and Stimulating Neural Activity
 Recording Neural Activity
 Microelectrode:
• A very fine electrode, generally used to record
activity of individual neurons.
 Single unit recording:
• Recording of the electrical activity of a single
neuron.
21
Copyright © 2004 Allyn and Bacon
Recording and Stimulating Neural Activity
 Recording with Macroelectrodes
 Macroelectrode:
• An electrode used to record the electrical activity
of large numbers of neurons in a particular region
of the brain; much larger than a microelectrode.
 Electroencephalogram (EEG):
• An electrical brain potential recorded by placing
electrodes on or in the scalp.
22
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Recording the Brain’s Metabolic and Synaptic Activity
 2-deoxytglucose (2-DG):
• A sugar that enters cells along with glucose but is
not metabolized.
 Autoradiography:
• A procedure that locates radioactive substances
in a slice of tissue; the radiation exposes a
photographic emulsion or a piece of film that
covers the tissue.
25
Copyright © 2004 Allyn and Bacon
Recording the Brain’s Metabolic and Synaptic Activity
 Fos:
• A protein produced in the nucleus of a neuron in
response to synaptic stimulation.
 Positron emission tomography (PET):
• A device that reveals the localization of a
radioactive tracer in a living brain.
 Functional MRI (fMRI):
• A modification of the MRI procedure that permits
the measurement of regional metabolism in the
brain.
26
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Measuring the Brain’s Secretions
 Measuring the Brain’s Secretions
 Microdialysis:
• A procedure for analyzing chemicals present in
the interstitial fluid through a small piece of tubing
made of a semipermeable membrane that is
implanted in the brain.
28
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Stimulating Neural Activity
 Multibarreled micropipette:
• A group of micropipettes attached together, used
to infuse several different substance by means of
iontophoresis while recording from a single
neuron.
 Microiontophroesis:
• A procedure that uses electricity to inject a
chemical from a micropipette to determine the
effects of the chemical on the electrical activity of
a cell.
30
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon
Neurochemical Methods
 Finding Neurons that Produce Particular
Neurochemicals
 In situ hybridization:
• The production of DNA complementary to a
particular messenger RNA to detect the presence
of the RNA.
33
Copyright © 2004 Allyn and Bacon
Copyright © 2004 Allyn and Bacon