Chapter 5
Methods and Strategies of
Research
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• Chapter 5 Outline
• Experimental Ablation
• Recording and Stimulating Neural Activity
• Neurochemical Methods
• Genetic Methods
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• Experimental Ablation
• Evaluating the behavioral effects of brain damage
• Experimental ablation (one of the oldest techniques
in neuroscience)
• The _____________________________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.
• Lesions __________________caused by strokes or other
impairments to the CNS, and they provide an
experimental platform for developing treatments.
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• Experimental Ablation
• Producing brain lesions
• Excitotoxic lesion
• A brain lesion produced by intracerebral injection
of an __________________, such as kainic acid.
(Kainic acid stimulate glutamate receptors)
• ____________lesion
• A placebo procedure that duplicates all the
steps of producing a brain lesion except for the
one that actually causes the brain damage.
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RF lesions
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Excitotoxic
Lesion
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• Experimental Ablation
• Stereotaxic surgery
• Stereotaxic surgery
• Brain surgery using a stereotaxic apparatus to
__________an electrode or cannula in a
__________position of the brain.
• Bregma
• The junction of the sagittal and coronal sutures of the
skull, often used as a ___________________for
stereotaxic brain surgery.
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• Experimental Ablation
• The stereotaxic atlas
• Stereotaxic atlas
• A collection of drawings of sections of the brain of a
particular animal with measurements that provide
________________for the stereotaxic surgery.
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• Experimental Ablation
• The stereotaxic apparatus
• Stereotaxic apparatus
• A device that permits a surgeon to position an
electrode or cannula into a specific part of the brain.
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• Steretaxic surgery methods developed first with
animals are used with human subjects to treat some
disorders.
• Parkinson’s disease
• Epilepsy
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• Histological Methods
• Fixation and sectioning
• Fixative
• A chemical such as formalin; used to prepare and
_____________ body tissue.
• Formalin
• The aqueous solution of formaldehyde gas; the most
•
•
•
commonly used tissue fixative.
Halts autolysis (self dissolving)
Hardens soft tissue
Kills microorganisms
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• Histological Methods
• Fixation and sectioning
• Microtome
• An instrument that produces very ___________of
•
•
body tissue.
1 to 80 micrometer thick (1-millionth of a meter).
Different ____________ are needed to make different
cellular structures visible for light or electron
microscopy.
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Cresyl violet stain
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• Histological Methods
• Electron microscopy (electron beam)
• ________________em is used for magnification
above 1500 x (the limit for light microscopy)
• ______________ electron microscope
• A microscope that provides three-dimensional
information about the shape of the surface of a small
object.
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• Tracing Neural Connections
• Tracing efferent axons
• (VMH neurons do not connect to muscles
directly, but the pathway of CNS connections
can be traced)
• Anterograde labeling method
• A histological method that labels the axons and
terminal buttons of neurons whose cell bodies are
located in a particular region.
• PHA-L
• Phaseolus vulgaris leukoagglutinin; a protein
derived from kidney beans and used as an
anterograde tracer; taken up by ____________and
carried to the ___________________.
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• Tracing Neural Connections
• Tracing efferent axons
• Immunocytochemical method
• A histological method that uses ________
antibodies or antibodies bound with a dye molecule to
indicate the presence of particular proteins of
peptides.
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VMH neurons project to the periaqueductal
gray matter (PGA).
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• 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. The chemical is carried
from the _________________________________.
• Fluorogold
• A dye that serves as a retrograde label that is taken
•
up by the terminal buttons and then carried back to
the cell bodies.
(Medial amygdala provides input to VMH)
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• Tracing Neural Connections
• Tracing afferent axons
• Anterograde and retrograde methods label just a
•
•
single link in a chain of neurons.
_______________ methods may trace several
links in the chain, and help establish a wiring
diagram.
Pseudorabies virus
• A weakened form of a pig virus; used for
•
transneuronal tracing which labels a series of
neurons that are interconnected synaptically.
The virus ___________________________ in the
chain. This method permits anterograde and
retrograde directions.
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• Study of the Living Human Brain
• Computerized tomography (CT)
• The use of a device that employs a computer to
analyze data obtained by a scanning beam of X-rays
to produce a
_________________________________________
________________________________________.
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Damaged area from a stroke
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• Study of the Living Human Brain
• Magnetic resonance imaging (MRI)
• A technique whereby the interior of the body can be
accurately imaged; involves the interaction between
_______________________________________.
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• Recording and Stimulating Neural Activity
• Recordings with microelectrodes
• 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.
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• Recording and Stimulating Neural Activity
• Recording with macroelectrodes
• Macroelectrode
• An electrode used to record the electrical activity of
_____________________in a particular region of
the brain; much larger than a ______________.
• Electroencephalogram (EEG)
• An electrical brain potential recorded by placing
electrodes on or in the scalp.
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• Recording and Stimulating Neural Activity
• Magnetoencephalography
• A procedure that detects groups of ________
activated neurons by means of the magnetic field
induced by their electrical activity.
• This procedure uses an array of superconducting
quantum interference devices, or ______________.
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• Recording the Brain’s Metabolic and Synaptic
Activity
• 2-deoxyglucose (2-DG)
• A sugar that enters cells along with glucose but is not
metabolized. _______ rates of metabolic activity are
revealed by the increased up take of 2-DG.
• 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.
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High level of activity in the hypothalamus
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• 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 (_____)
• The use of a device that reveals the localization of a
radioactive tracer in a living brain.
• Functional MRI (______)
• A modification of the MRI procedure that permits the
measurement of regional metabolism in the brain.
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FOS stain indicates the neurons activated
during copulation (rat forebrain).
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Rate of up
take of 2DG.
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• Functional MRI scans have higher ____________
•
than PET scans, and can be acquired at a faster rate.
Thus they reveal more detailed information than PET
scans.
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Judgments of rhyming words
Female
Male
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• 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.
A technique used to measure secretions of
____________________________________.
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• In humans fetal dopaminergic neurons have been
•
___________ in the basal ganglia of some
Parkinson’s patients.
The transplant greated diminished the symptoms of
Parkinson’s disease.
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More dopamine secreted
after the implant.
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Chemicals are infused to
stimulate the brain.
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• Behavioral Effects of Electrical Stimulation
• Transcranial magnetic stimulation (TMS)
• Stimulation of the cerebral cortex by means of magnetic
fields produced by passing pulses of electricity through a
coil of wire placed next to the skull; interferes with the
functions of the brain region that is stimulated.
• TMS has been used to disrupt the activity of some over active brain
centers associated with depression.
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• Neurochemical Methods
• Organophosphate insecticides
• Human exposure to insecticides that contain
•
acetylcholinesterase inhibitors (acetylcholine agonists)
could cause intense, bizarre dreams and walking
hallucination.
The insecticide directly activated the neural circuits
responsible for dreaming.
• Neurochemical methods can be used to determine the
location of an enormous variety of substances in the
brain. These methods can be used to localize
neurotransmitters themselves, or the enzymes that
produce them.
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Rat
forebrain
terminal
buttons that
secrete
vasopressin.
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Choline acetyltransferase in the pons
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• Genetic Methods
• Targeted mutations
• A mutated gene )also called a __________________
produced in the laboratory and inserted into the
chromosomes of mice; fails to produce a functional
protein.
• Antisense oligonucleotide
• A modified strand of RNA or DNA that binds with a
specific molecule of messenger RNA and prevents it
from producing it particular protein.
• These methods have the potential to reduce the
likelihood of some individual developing inherited
disorders or some addictions.
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