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Flashcards in FOUNDATIONS: METHODS AND IMAGING Deck (35)
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1
Q

What is an MEG?

A

MEG measures the magnetic field generated by neurons and is better than EEG for looking at neural activity in brain and measures activity much faster than MRI.

2
Q

What do researchers study on the mesoscale?

A

researchers see how smaller regions of the brain communicate along single axons at micrometre or submicrometre resolution. It is like adding in the lanes of highways and local streets.

3
Q

What does mesoscale mean?

A

Complex cellular networks in brain regions

4
Q

What do researhers study in the macroscale?

A

Detecting how bundles of axon fibres connect large regions together (brain regions and areas)

5
Q

What do researchers study in the microscale?

A

Cells in complex cellular networks. Microscale images reveal individual neurons and synapses at resolutions of a few nanometres — akin to a map that shows even footpaths and stepping stones.

6
Q

What is the nanoscale?

A

Receptor mosaics within a cell membrane.

7
Q

What quantity of neurons does the mesoscale look at?

A

1000-1M neurons

8
Q

What quantity of neurons does the microscale look at?

A

1-100s of neurons

9
Q

What is studied in the microseconds?

A

Channel openings

10
Q

What is studied in the milliseconds?

A

Action potentials

11
Q

What is studied in the tens of milliseconds?

A

Perception, motor control, reaction times

12
Q

What is studied in seconds and above?

A

Learning

13
Q

What is studied in years?

A

Neurodevelopment; diseases such as alzheimers, MS, parkinsons

14
Q

What is the difference between MRI and fMRI?

A

MRI is the energy emitted from the ‘spin’ of H atoms in a strong magnetic field.

  • fMRI is when localised changes in brain activity are associated with changes in blood oxygenation. fMRI can detect magnetisation changes b/w oxygenated and deoxygenated haemoglobin.
15
Q

In FMRI what does BOLD stand for?

A

Blood Oxygen Level Dependent

16
Q

What is functional connectivity?

A

Correlation between spatially distinct brain

regions

17
Q

What applications can we use functional connectivity in?

A

Looking at how people with schizophrenia are functionally different from siblings

18
Q

What is an EEG?

A

Measures potential difference across the head (b/w pairs of electrodes)

  • has much better temporal resolution than fMRI
  • is done when someone is performing tasks
  • inexpensive
  • poor spacial resolution
19
Q

What is temporal resolution?

A

The amount of time it takes to acquire multiple images one after another in imaging.
e.g. If the TR is 10ms and there are 5 views per segment, the temporal resolution would be 50ms.

20
Q

What is spacial resolution?

A

The size of the voxels which is determined by the matrix size, field of view (FOV) and the slice thickness

21
Q

What is the approximate resting membrane potential?

A

Approx -65mV

22
Q

What are the electrodes made from in INTRAcellular recordings?

A

Saline filled micro pipettes (KCl, NaCl)

23
Q

What are the electrodes made from in EXTRAcellular recordings ?

A

Insulated metal

24
Q

What is Transcranial Magnetic Stimulation?

A

Induces a change in current flow in localised sections of the brain

25
Q

What is intracellular microstimulation?

A

When current is injected into a single cell that changes the membrane potential (similar to a neurotransmitter being released)

26
Q

What is CT?

A

Computerised tomography

  • X RAY source rotated around the head in plane of ideal cross section
  • computer uses relative radiopacity to make an algorithm
27
Q

What did CT scans reveal?

A

Gross organisation of gray and white matter AND position of ventricles

28
Q

What is DTI?

A

Diffusion Tensor Imaging

  • Large visualisation of axons in the brain (connecting of different regions)
  • The position of H atoms in H2O can be measure d in brain
29
Q

What is the name for the imaging method that measures the diffusion of water in the brain over time?

A

DTI (Diffusion Tensor Imaging)

30
Q

What can an MRI reveal and what type of signal does it involve?

A

Involves radio signals and can reveal lesions in brain (tumors and inflammation increase extracellular water)

31
Q

What is a PET scan?

A

Positron Emission Tomography

  • Looks at blood flow in the brain and metabolism ( like fMRI)
  • Radioactive solution containing atoms that emit positrons (e+) is injected in bloodstream
  • 19F9 is radio isotop used
32
Q

In PET scans, how is the positron emission (flourine) used to detect tumors?

A
  • It is attached to 2-deoxyglucose (2-DG- analogue of glucose) in bloodstream
  • Migrates to brain
  • Metabolically active neurons that use glucose normally take up 2-DG and phosphorylate it so it can’t get out of cell
  • Amount of radioactive 2-DG and number of beta+ emissions accumulated in neuron indicate the level of metabolic activity hence tumor growth (high metabolic activity)
33
Q

What is common (in a general sense) between PET and fMRI scans?

A

They BOTH look at blood flow in the brain and metabolic activity

34
Q

What does intracellular recording involve?

A

Impaling the neuron or axon with microelectrode
- It measures the potential difference between the tip of the INTRACELLULAR ELECTRODE (filled with concentrated KCl solution) and another electrode connected to ground

35
Q

What do extracellular electrodes contain and what is the purpose of them?

A
  • Electrodes (fine glass capillary with salt solution or metal)are placed NEAR the membrane