Lecture 1 & First Week Assignments Flashcards
What are in vitro models concerned with? (3)
- Bacteria/ Yeast cells
- Cell structure
- Tissue slice
What are in vivo models concerned with? (3)
- Invertebrates
- Animal
- Human
What are in silico models concerned with?
Computers
Why are rats popular as study animals? (6)
- Cheap housing/ maintenance/ breeding
- Friendly disposition- easy handling
- Relatively intelligent and agile
- Resistant to infection
- Many inbred strains available
- A lot of information known
Why are mice so popular?
-Convenient genetic manipulation
What two broad types of experimental techniques are there?
Manipulation and monitoring
What five types of manipulating experiments are mentioned?
Lesions Electrical stimulation Pharmacological Genetic manipulation Behavioural manipulation
What types of lesions are there? (4)
Mechanical
Electrolysis
Chemical e.g Ibotenic acid- only cells are destroyed. Fibers of passage are spared
What two broadtypes of monitoring techniques are there?
In vivo and Ex vivo
What three types of In vivo monitoring techniques are there?
- Electrophysiology (electrical)
- Micro-dialysis (chemical)
- Behavioural evaluation (tasks)
What types of ex vivo monitoring techniques are there?
Localisation/ Quantification of tissue components in situ
Quantification of components in tissue homogenates
What does the stereotaxic apparatus entail?
A stereotaxic frame is a research (or medical) tool allowing fixation of the head in a standardised way. Vernier bars in three dimensions allow precision manipulation of drills, electrodes, liquid probes and other instruments in the brain.
How can this apparatus be used on humans?
In neurosurgical practice, this allows a.o. for precision targeting of tumours or epileptic cells, or the insertion of electrodes for deep brain stimulation.
How is the stereotaxic apparatus used on a rat?
In case of the rat; an fully anaesthetised specimen is fixated in the stereotaxic frame by way of an incisor bar (a bar below its upper jaw incisors) and a metal pin in each ear canal.
Name and describe the three reference points on the skull of the rat
The interaural line, is one point of reference that can be used to navigate the rat brain. It is the line you can draw between the ear canals.
Bregma, is the second point of reference. It is the point on the skull where the frontal bone meets the parietal bones, or the intersection between the coronal and sagittal sutures.
In some cases, lambda (the point where the occipital bone meets the parietal bones, 9 mm posterior to bregma) may also be used.
What are these three reference points used for?
On the basis of these reference points a three dimensional coordinate system is used to describe any location in the brain, with a anterior-posteror-axis (AP), a medio-lateral axis (ML) and the dorso-ventral axis (DV). Point Bregma (AP, ML, DV) has coordinates (0, 0, 0).
How much do locations of brain nuclei vary between rats? What implications does this have?
In rats of a similar age class, variation between the location of brain nuclei with respect to bregma is below 0.5 mm. This coordinate system allows for a precise communication about the location of brain structures: e.g. the corpus callosum extends from bregma 2.2 to bregma -4.52. (in other words, it starts 2.2 mm anterior to bregma, and ends 4.52 mm posterior to bregma).
What can be done for smaller or bigger rats
For smaller or bigger rats a simple scaling can be applied on the basis of the distance between Bregma and Lambda.
In Paxinos and Watson’s atlas, what type of cuts and how far apart are they?
high-resolution drawings of 65 subsequent coronal sections (about 0.25 mm apart) , starting at the level of olfactory bulbs and extending to the posterior cerebellum and medulla oblongata.
What in the level at which each section has been cut indicated by?
The level at which each section has been cut is indicated with bregma (dorsal) and interaural line (ventral) coordinates. If a section has been cut exactly in the coronal plane, the interaural line is always 9 millimeters behind bregma (Interaural -9 =bregma). However, if a section has been cut at an angle, reporting both bregma and interaural coordinates allows for precise reproduction of that angle.
What do the capitals in the index indicate? How else is this represented in the drawings?
Grey matter (nuclei and laminae) are indicated with CAPITALS, white matter in lower case letters. In the drawings, white matter is outlined with a solid line, grey matter with dotted lines.
How do you find the anterior posterior co-ordinates on a given page?
Top left hand corner shows where the section is cut
How are ventricals drawn in diagrams?
Ventricles are depicted in solid blue or black.
What do bold lines indicate in diagrams
Borders of tissue.
In the anterior and posterior part of the brain, where does the corpus callosum split?
In the anterior part of the brain the corpus callosum splits into the forceps minor and in the posterior part of the brain into the forceps major.
In order to study tissue under a microscope, it has to be cut into thin slices. What is a pre-requisite for this and how can it be accomplished?
A prerequisite is that the tissue is, and stays, in prime condition. This can be accomplished by either freezing or fixating.
When is it preferred freezing and when fixated?
If retention of fatty tissue and certain heat-sensitive proteins is required, freezing techniques are generally applied.
when paraffin is used for embedding of the tissue, prior fixation is required. This is the case for the brain slices used in the 2nd practical with this course: the tissue has been fixated in paraformaldehyde, embedded in paraffin, sliced, and then deparafinnated.
After freezing, how can the tissue be cut?
After freezing, the tissue can be cut with a cryostate or a sled microtome
What is the purpose of fixation? (4)
- Giving the tissue a certain degree of rigidity
- Keeping intra- and extracellular structures in place
- Making the tissue fit for histological staining
- Making the tissue permeable for the substance used for embedding.
What may be used for fixating? What does this depend on?
Various compounds (e.g. ethanol, formaldehyde) or mixes (e.g. Bouin’s fixative) may be used for fixation; the selection depends on both the type of tissue and on what it is we need to be able to study
Considering bacteria and yeast cells do not have a nervous system, how is in vitro neuroscience research concerned with them?
They can be used to express molecules of the nervous system for example receptors such as yeast cells and dopamine receptors
How is studying cell cultures of interest to neuroscience research?
Neurons can be grown together on a petri dish connected to each other to form a network. This is handy to investigate interneuron communication. They can be reached very easily with micro electrodes and expose them to antibiotics, neurotransmitters etc to see how they react.
how are tissue slices of interest to neuroscience research?
They can be kept alive to stimulate some structures and record from other structures. This gives good access to cells without the complexity of recording from a brain that is in an animal
Why are computers used in neuroscience research?
To simulate neural structures and processes or other molecules to see how they interact with each other.
What percent of animals used in research are 1) rodents and 2) more complex animals (dogs, cats, monkeys)
1) 90%
2) 1%
How is electrical stimulation used in experimental manipulation?
To excite or inhibit neural function
Give three examples of pharmacological methods of experimental manipulation
=> Systemic, intracerebroventricular, or local intracerebral injection
=>Osmotic pumps
=>Microdialysis
How are organisms motivated in behavioural manipulation?
appetitive (rewarding) or aversive stimuli
