5. Techniques in Neuroscience

Question 1

Define electrophysiology

Answer 1

Branch of physiology that deals with electrical phenomena associated with nervous and other bodily activity

Question 2

Define single unit recording

Answer 2

Studies the electrical activity of individual neurons (one single neurone) - in animals

Question 3

Define multi-unit recording

Answer 3

Studies the composite electrical activity of groups of neurons (e.g. fiber pathway) - neurons acting at the same time - in animals

Question 4

Define EEG recording

Answer 4

Studies the low frequency, composite electrical activity of unspecified origin at select brain regions

Question 5

What does single unit recording use and electrode for?

Answer 5

To record the electrophysiological activity from a single neuron

Question 6

What does the electrode detect (single unit recording)?

Answer 6

Electrical activity generated by the neurons adjacent to the electrode tip

Question 7

What does single unit recoding allow researchers to understand?

Answer 7

How individual neurons code information

Question 8

Are Electroencephalograms (EEG) invasive?

Answer 8

No

Question 9

What do EEGs measure?

Answer 9

Voltage differences at the scalp in the microvolt range

Question 10

Describe EEGs in terms of spatial resolution

Answer 10

Spatial resolution is poor as multiple neurons are under one electrode so they aren’t very specific

Question 11

Describe EEGs in terms of temporal resolution

Answer 11

Terrific - 1ms delay

Question 12

Why are EEGs used?

Answer 12

Detecting changes in brain patterns
Can average several readings to obtain evoked potential
Often used for detecting epilepsy

Question 13

EEG signals reflect what?

Answer 13

Global brain states

Question 14

Large background oscillations of the EEG trace make it impossible to do what?

Answer 14

Detect evoked response from a single trial

Question 15

By averaging from hundreds of trials, the background EEG is removed, which leaves what?

Answer 15

Event-related potentials

Question 16

What is an event-related potential (ERP)?

Answer 16

The measured brain response that is the direct result of a specific sensory, cognitive or motor event

Question 17

EEGs measure the population responses of how many neurons?

Answer 17

Millions

Question 18

EEG signal is directed related to what type of activity?

Answer 18

Neural activity

Question 19

Neural activity consumes what as well as generating electrical signals?

Answer 19

Oxygen

Question 20

What does PET measure?

Answer 20

The blood flow in a region

Question 21

What does fMRI measure?

Answer 21

Blood oxygenation

Question 22

The time taken for changes in blood flow is slow (several seconds) so therefore imagine has poor….

Answer 22

Temporal resolution

Question 23

Cerebral blood flow (CBF) is the basis of what type of technique?

Answer 23

fMRI

Question 24

The cortex is densely packed with…

Answer 24

Blood vessels

Question 25

What does the distribution of blood vessels mirror?

Answer 25

Neuronal organisation

Question 26

At what level does PET measure blood flow?

Answer 26

Locally

Question 27

PET is a form of what type of functional brain imagine?

Answer 27

Hemodynamically-based

Question 28

Before PET, a subject is given a radioactively….

Answer 28

Tagged substance

Question 29

PET will compute the locations of…

Answer 29

Decaying radioisotopes that emit game rays

Question 30

From PET we can infer higher regional cerebral blood flow in areas that emit what?

Answer 30

Many positrons

Question 31

How long does the tracer take to peak for PET?

Answer 31

up to 30 seconds

Question 32

Give 4 limitations of PET

Answer 32

1. Limited spatial resolution
2. No temporal resolution
3. Exposure to radiation
4. Access to a cyclotron

Question 33

What does fMRI stand for?

Answer 33

Functional Magnetic Resonance Imagine

Question 34

What does fMRI measure?

Answer 34

Local blood flow

Question 35

fMRI measures the concentration of what in the blood?

Answer 35

Deoxyhemoglobin

Question 36

What is the BOLD response?

Answer 36

the Blood Oxygen Level Dependent contrast

Question 37

The change in BOLD response over time is called the…

Answer 37

Haemodynamic response function

Question 38

How many seconds does it take the haemodynamic response function to peak and what does this mean for temporal solution?

Answer 38

6-8 seconds and therefore a low temporal solution

Question 39

Magnetic field strength is measured in what?

Answer 39

Tesla (T) Gauss (G)

Question 40

1 Tesla = n G

Answer 40

n = 10,000

Question 41

The brain has a constant supply of blood flow and therefore to determine if an area is active, one must compare…

Answer 41

Relative differences in brain activity between two or more conditions

Question 42

fMRI determines that a region is ‘active’ if it shows what?

Answer 42

A greater response in one condition relative to another

Question 43

List 4 limitations of fMRI

Answer 43

1. Lacks spatial and temporal resolution
2. Is not a direct measure of neural activity
3. The precise link between CBF and neural activity is not yet known
4. Caution must be taken in the interpretation of fMRI measurements

Question 44

What does TMS stand for and what does it do?

Answer 44

Transcranial Magnetic Stimulation & it uses electro-magnetic induction via coils to temporarily disrupt cortical function

Question 45

What does TMS impair and how is this useful to infer?

Answer 45

It impairs local processing and we can therefore infer what this area is used for

Question 46

The TMS coil contains a wire carrying…

Answer 46

Electrical current

Question 47

A rapid change in current creates what?

Answer 47

A magnetic field

Question 48

The magnetic field induces what?

Answer 48

A current in the nearby neurons

Question 49

Which areas can TMS stimulate?

Answer 49

Those near the cortical surface