ABLATUS

meaning "carrying away"

In Experimental ablation, do the scientists usually remove the brain tissue?

No. Normally leaves the damaged portion in its place.

OLDEST METHOD USED IN NEUROSCIENCE

Experminental ablation

LESION VS BRAIN LESION

LESION- THE ACTUAL INJURY.

BRAIN LESION- THE DAMAGE FROM THE LESION

CIRCUITS IN THE BRAIN PERFORM...

FUNCTIONS, NOT BEHAVIORS.

THE RESEARCHER'S JOB IS TO

DETERMINE WHAT CIRCUITS OF NEURONS IN THE BRAIN ARE RESPONSIBLE FOR EACH OF THESE FUNCTIONS

PROCESS OF PERFORMING A LESION

1. ANESTETHIZE THE ANIMAL

2. CUT OPEN THE SCALP.

3. REMOVE PART OF THE SKULL

4. CUT THROUGH THE DURA MATER (BRINGING THE CORTEX IN VIEW)

5. SUCTION

REGIONS LOCATED BENEATH THE CORTEX

SUBCORTICAL

SUBCORTICAL LESIONS USUALLY DONE BY

PASSING ELECTRICAL CURRENTS STEREOTAXICALLY WITH A WIRE AND USE A LESION MAKING DEVICE THAT GIVES OF RF CURRENT. WILL DESTROY EVERYTHING IN THE PROXIMITY OF THE ELECTRODE TIP

EXCITOTOXIC LESION

AN EXCITOXIC AMINO ACID (KAINIC ACID) THAT STIMULATES NEURONS TO DEATH. DOES NOT KILL SURROUNDING AXONS THAT BELONG TO OTHER NEURONS.

SHAM LESIONS

A  "PLACEBO" PROCEDURE THAT DUPLICATES ALL STEPS OF PRODUCING A LESION EXCEPT FOR THE ONE THAT ACTUALLY CAUSES THE DAMAGE.

THE PEOPLE WITH SHAM LESIONS ARE APART OF

THE CONTROL GROUP

STEREOTAXIC SURGERY

BRAIN SURGERY USING A STEREOTAXIC APPARATUS TO POSITION AN ELECTRODE IN A SPECIFIED POSITION OF THE BRAIN

SUTURES (SEAMS)

THE SKULL IS COMPOSED OF SEVERAL BONES THAT GROW TOGETHER AND FORM SUTRES. 

THE JUNCTION OF SUTURES OF THE SKYLL. NORMALLY USED AS REFERENCE POINT FOR STEREOTAXIC SURGERY

BREGMA

STEREOTAXIC ATLAS

CONTAINS PHOTOGRAPHS OR DRAWINGS THAT CORRESPOND TO FRONTAL SECTIONS TAKEN. PROVIDE COORDINATES FOR STTXC SURGERY

1. GET COORDINATES FROM ATLAS

2. ANESTETHIZE

3. PLACE IN APPARATUS

4. CUT SKULL OPEN

5. LOCATE BREGMA

6. DIAL IN APPROPRIATE NUMBERS

7. DRILL HOLE THROUGH SKULL

8. LOWER DEVICE

STTXIC SURGERY CAN BE USED FOR OTHER THINGS

STIMULATING NEURONS/DESTROY THEM

OR

INSERT MEDS THAT WILL DO THIS

HISTOLOGICAL METHODS

FIX, SLICE, STAIN, AND EXAMINE

TO PRESERVE TISSUE.

MOST POPULAR: FORMALIN (AQUEOUS SOLN OF FORMALDEHIDE GAS)

SCANNING ELECTRON MICROSCOPE

PROVIDES 3D INFORMATION ABOUT THE SHAPE OF THE SURFACE OF A SMALL OBJECT. TRANSMITS THE ELECTRON BEAM THROUGH THE TISSUE

The use of a device that employs a computer to analyze data by a scanning beam of X rays to produce a 2 dimensional picture of a "slice" through the body.

The Xray passes through the patient's head, detector measures amount of radioactivity. Looks at head from all angles, translates the numbers into pictures of the skull and its contents.

A technique where the interior of the body can be accurately imaged, involves the interaction between radiowaves and a strong magnetic field.

to see small fiber bundles not seen on MRI screen.

An imaging method that uses a modified MRI scanner to reveal bundles of myelinated axons in the living human being.

An electrical brain potential recorded by placing electrodes on the scalp.

Another use is to monitor brain condition during surgical procedures that could damage it.

Locate radioactive substances in a tissue; mounted on microscope slides, put in a dark room, coted with photographic emulsion. Several weeks later, the radioactvity shows the emulsion. The 2-dg shows up silver.

The most radioactive regions of the brain will appear as dark spots on the emulsion.

reveals the localization of radioactive tracer in the brain.

(Expensive)

Three possibilities:

1. Look for neurons containing the drug.

2. Look for enzymes that must be present in the cells' membranes to receive input from neurons

3. Look for receptors.

Expose slices of brain tissue to a soln containing a radioactive ligand for a particular receptor.

Then rinse slices so that the only radioactivity remaining in them is that of the molecules of the ligand bound to their receptors.

Finally, use autoradio to locate the ligand and thus the receptors.

If both twins have been diagnosed, they are concordant.

If one has, the twins are discordant.