Lecture 3 Methods and Microanatomy

Question 1

Example of Lesions revealing functions.

Answer 1

Gage getting impaled by a railroad spike:
Gage’s personality changed so radically that
he was “no longer Gage.”

Question 2

Example of electrical Stimulation revealing function

Answer 2

Early insights into cortical organization were made by directly stimulating the cortex w electricity Done in awake humans undergoing neurosurgery.
- Penfield and Jasper (1954) examined the effect of small electrical currents on the cortical surface.

Question 3

What is Transmagnetic Stimulation (TMS)

Answer 3

• Modern brain stimulation technique
• Transcranial magnetic stimulation (TMS) briefly stimulates discrete cortical regions.
  Scientists can then record observed changes in behaviour.

Question 4

What are X-rays, CT/CAT scans?

List the advantages n disadvantages

Answer 4

X-rays pass through the body and are absorbed or attenuated (weakened) at differing levels creating a profile of x-ray beams of
different strength. This x-ray profile is registered on film, thus creating an image.

CT Scans are essentially many x-rays taken at different positions to generate a “map”

Advantages
- Painless
- Spatial Resolution
Disadvantages
- exposure to radiation
- CT scanning is, in general, not recommended for pregnant women.

Question 5

What is an MRI, how does it work?
What is the difference between an fMRI and MRI

Answer 5

Magnetic force causes most atoms to point north or south, radio wave is applied causing unmatched atoms to spin in opposite direction, when radio wave done the atoms return to the original position and release energy, energy converted into an image

MRI
* High resolution
* Often used to measure the volume of structures.
* Can even reveal different types of structures

fMRI
- Generates images based on the brain’s activity rather than structure.
- High Temporal Resolution
- Decent Spatial resolution (at gross anatomical level)

Question 6

what are the advantages and disadvantages of MRIs?

Answer 6

Advantages
- Multiples sequences can be used
- Good spatial resolution
- Generally safe and non- invasive Full brain coverage
Disadvantages
- Poor temporal
- resolution (better with fMRI)
- Not a direct measure of neural activity

Question 7

How do PET scans work?

Answer 7

• Positron Emission Tomography
  Works by inserting a radioactive tracer into glucose and when glucose is uptaken by the brain can track what parts of the brain are active and using energy.

Question 8

What are the differences between multi, bi, and unipolar neurons.

Answer 8

Multipolar has many dendrites extending from the cell and a single axon
Bipolar neuron has a single dendrite extending from the cell and a single axon
unipolar has a single branch that extends out that serves as a dendrite and axon

Question 9

What are the Major parts of a neuron? I I C O

Answer 9

Input zone, where neurons collect and process information

Integration zone, where the decision to produce a neural signal is made.

Conduction zone, where information can be electrically transmitted over great distances

Output zone, where the neuron transfers information to other cells

Question 10

What do glial cells do?

Answer 10

Glial Cells Support Axon Function
- Glial cells assist neuronal activity by providing raw materials, chemical signals, and
structure
- Myelination via: Oligodendrocytes, Schwan cells
Oligodendrocytes in the CNS
Schwan cells in the PNS

Question 11

What are some Histological Methods for Studying Neurons?
C N G I B

Answer 11

Cryostat procedure for tissue preparation
- Sections of tissues are mounted onto a slide
- Stains are applied to visualize different parts/types of neurons.

The Nissl Stain
- selectively label negatively charged molecules such as DNA and RNA.
- Great for counting neurons

The Golgi Stain
- The black reaction. Silver nitrate infused cells Golgi stains completely label only a
few cells (<10%).
- All parts are visible.

Immuno staining
- Antibody targeted staining Selectively identifies antigens that can identify selective
types of neurons.

Brainbow
- Genetic labelling
- Allows for 100’s of neurons to be mapped

Question 12

Define the Following:
Diffusion
Osmosis
Semi-permeable membranes
Electrochemical gradient
Active transport

Answer 12

• Diffusion: the distribution of ions in a medium.
• Osmosis: the diffusion of molecules from a high concentration gradient to a low concentration gradient
• Semi-permeable membranes: can create differences in diffusion in a medium.
• Electrochemical attraction can also influence the movement of ions towards one another
• Active transport: carries molecules across a membrane