19.1 Methods of Study of the Nervous System

Question 1

What are the main histological techniques used to study neurons and what is each used for?

[IMPORTANT]

Answer 1

• Nissl staining -> For cell nuclei
• Golgi stain (silver stain) -> For cell morphology
• Weigert stain -> For axon tracts
• Immunocytochemistry
• In situ hybridisation

Question 2

What is immunohistochemistry and how can it be used in neuroscience?

[IMPORTANT]

Answer 2

• 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

Question 3

What is in situ hybridisation?

[IMPORTANT]

Answer 3

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).

Question 4

What technique is this?

Answer 4

Golgi staining

Question 5

What technique is this?

Answer 5

Nissl staining

Question 6

What technique is this?

Answer 6

Weigert staining

Question 7

What type of microscopy of the brain is shown here?

Answer 7

Light microscopy

Question 8

What type of microscopy of the brain is shown here?

Answer 8

Electron microscopy

Question 9

What type of microscopy of the brain is shown here?

Answer 9

Fluorescence microscopy

Question 10

What enables the imaging of neurotransmitter vesicles at a synaptic cleft?

Answer 10

Fluorescence microscopy dyes (FM)

Question 11

fMRI

Answer 11

What enables imaging areas of functional activity in the CNS?

Question 12

What method gives a direct measure of the activity of large populations of nerve cells?

Answer 12

EEG

Question 13

What method produces images of pre- and postsynaptic specialisations for synaptic transmission?

Answer 13

Electron microscopy

Question 14

Imaging technique used

Answer 14

CT

Question 14

What method uses changes in blood oxygenation to give an indirect measure of neural activity within the CNS?

Answer 14

fMRI

Question 15

What method of study has been used to visualise the brain in this image?

Answer 15

MRI

Question 16

CT scan

Answer 16

X-ray beams to produce images that depict tissues in 2D and 3D dimensions based on density

Question 17

PET scan

Answer 17

Asminister radioactive fluorescent glucose analogue; distributed throughout brain for assessment of brain activity

Question 17

Imaging technique used

Answer 17

PET scan

Question 18

EEG

Answer 18

Detect surface, residual currents to image brain activity; used in diagnosis of Epilepsy

Question 19

MEG

Answer 19

Magnetoencephalography; allows measurement of magnetic fields produced by brain electrical activity (brain waves)

Question 20

What are the limitations of the Golgi stain?

Answer 20

Golgi stain only picks up about 1 in 100 neurons

Question 21

What stain is shown below?

Answer 21

Golgi stain - silver nitrate and potassium dichromate

Question 22

How can MRI and CT be distinguished in the brain?

Answer 22

MRI= CSF and ventricles will appear WHITE and skull is black
CT= CSF and ventricles will appear BLACK and skull is white

Question 23

What is functional MRI?

Answer 23

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.

Question 24

What technique is shown below?

Answer 24

fMRI

Question 25

What is a PET scan?

Answer 25

(positron-emission tomography)
positron-producing radioactive marker (undergoing β+ decay) is injected for the imaging of blood flow to give better resolution than fMRI

Question 26

What technique is A?

Answer 26

CT

Question 27

What technique is B?

Answer 27

MRI

Question 28

What is C?

Answer 28

PET scan

Question 29

What is an EEG (electroencephalogram) ?

Answer 29

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

Question 30

What is EEG used for clinically?

Answer 30

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

Question 31

What are patch clamp recordings?

Answer 31

‘clamp’ the voltage to an experimental level and measure ionic currents across a single or a couple ion channels (patch)

Question 32

How are intracellular and extracellular recordings made?

Answer 32

fine microelectrodes, piercing into single axons to detect their firing

Question 33

What colour do nuclei appear under H&E staining?

Answer 33

Nuclei and structures rich in nucleic acids stain purple because they are acidic and bind to basophilic dyes

Question 34

What type of dye is haemotoxylin?

Answer 34

Basic dye = binds to acidic compounds = nucleic acids

Question 35

What colour does eosin appear as?

Answer 35

Pink

Question 36

What compounds does eosin bind to?

Answer 36

Basic proteins that are acidophilic because its an acidic dye

Question 37

What are different recording methods in electrophysiology?

Answer 37

field, extracellular, intracellular, patch.