19.1 Methods of Study of the Nervous System Flashcards
What are the main histological techniques used to study neurons and what is each used for?
[IMPORTANT]
- Nissl staining -> For cell nuclei
- Golgi stain (silver stain) -> For cell morphology
- Weigert stain -> For axon tracts
- Immunocytochemistry
- In situ hybridisation
What is immunohistochemistry and how can it be used in neuroscience?
[IMPORTANT]
- It is the staining of a certain type of protein using labelled antibodies
- This can be used to, for example, detecting neurons containing a certain type of neurotransmitter
What is in situ hybridisation?
[IMPORTANT]
Use of labeled complementary DNA, RNA or modified nucleic acids strand (i.e. a probe) to localise a specific DNA or RNA sequence in a portion or section of tissue (in situ).
What technique is this?
Golgi staining
What technique is this?
Nissl staining
What technique is this?
Weigert staining
What type of microscopy of the brain is shown here?
Light microscopy
What type of microscopy of the brain is shown here?
Electron microscopy
What type of microscopy of the brain is shown here?
Fluorescence microscopy
What enables the imaging of neurotransmitter vesicles at a synaptic cleft?
Fluorescence microscopy dyes (FM)
fMRI
What enables imaging areas of functional activity in the CNS?
What method gives a direct measure of the activity of large populations of nerve cells?
EEG
What method produces images of pre- and postsynaptic specialisations for synaptic transmission?
Electron microscopy
Imaging technique used
CT
What method uses changes in blood oxygenation to give an indirect measure of neural activity within the CNS?
fMRI
What method of study has been used to visualise the brain in this image?
MRI
CT scan
X-ray beams to produce images that depict tissues in 2D and 3D dimensions based on density
PET scan
Asminister radioactive fluorescent glucose analogue; distributed throughout brain for assessment of brain activity
Imaging technique used
PET scan
EEG
Detect surface, residual currents to image brain activity; used in diagnosis of Epilepsy
MEG
Magnetoencephalography; allows measurement of magnetic fields produced by brain electrical activity (brain waves)
What are the limitations of the Golgi stain?
Golgi stain only picks up about 1 in 100 neurons
What stain is shown below?
Golgi stain - silver nitrate and potassium dichromate
How can MRI and CT be distinguished in the brain?
MRI= CSF and ventricles will appear WHITE and skull is black
CT= CSF and ventricles will appear BLACK and skull is white
What is functional MRI?
uses a contrast medium (BOLD) in order to detect where the most blood flow in the brain is. Because the vasculature of the CNS is dynamic, and blood is delivered to neural tissue in a proportional manner to activity.
What technique is shown below?
fMRI
What is a PET scan?
(positron-emission tomography)
positron-producing radioactive marker (undergoing β+ decay) is injected for the imaging of blood flow to give better resolution than fMRI
What technique is A?
CT
What technique is B?
MRI
What is C?
PET scan
What is an EEG (electroencephalogram) ?
electrodes are placed in a noninvasive manner along the scalp of an individual, allowing them to detect residual currents similarly to the ECG as neurons depolarise and action potentials are fired in a perpendicular direction to the sensors
What is EEG used for clinically?
This gives to the characteristic oscillations in brain activity seen on a normal EEG.
The technique is classically used in the diagnosis of epilepsy, although abnormalities on the results can be indicative of a wide range of other issues from sleep disorders to abnormal anaesthesia
What are patch clamp recordings?
‘clamp’ the voltage to an experimental level and measure ionic currents across a single or a couple ion channels (patch)
How are intracellular and extracellular recordings made?
fine microelectrodes, piercing into single axons to detect their firing
What colour do nuclei appear under H&E staining?
Nuclei and structures rich in nucleic acids stain purple because they are acidic and bind to basophilic dyes
What type of dye is haemotoxylin?
Basic dye = binds to acidic compounds = nucleic acids
What colour does eosin appear as?
Pink
What compounds does eosin bind to?
Basic proteins that are acidophilic because its an acidic dye
What are different recording methods in electrophysiology?
field, extracellular, intracellular, patch.
