Chapter 5
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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.
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.
sham lesion
A "placebo" procedure that duplicates all the steps of producing a brain lesion except for the one that actually causes the brain damage.
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.
stereotaxic atlas
A collection of drawings of sections of the brain of a particular animal with measurements that provide coordinates for stereotaxic surgery.
stereotaxic apparatus
A device that permits a surgeon to position an electrode or cannula into a specific part of the brain.
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.
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 tissues.
scanning electron microscope
A microscope that provides three-dimensional information about the shape of the surface of a small object.
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 lima beans used as an anterograde tracer; taken up by dendrites and cell bodies and carried to the ends of the 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.
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 terminal buttons and carried back to the cell bodies.
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 two-dimensional picture of a "slice" through the body.
magnetic resonance imaging/MRI
An technique whereby the interior of the body can be accurately imaged; involves the interaction between radio waves and a strong magnetic field.
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.
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 in the scalp.
2-deoxyglucose/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.
Fos
A protein produced in the nucleus of a neuron in response to synaptic stimulation.
positron emission tomography/PET
The use of 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.
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.
multi-barreled micropipette
A group of micropipettes attached together, used to infuse several different substances by means of iontophoresis while recording from a single neuron.
microiontophoresis
A procedure that uses electricity to eject a chemical from a micropipette in order to determine the effects of the chemical on the electrical activity of a cell.
in situ hybridization
The production of DNA complementary to a particular messenger RNA in order to detect the presence of the RNA.
double labeling
Labeling neurons in a particular region by two different means; for example, by using an anterograde tracer and a label for a particular enzyme.