B&B 2/2

Question 1

What are the 4 main methods of investigating the brain?

Answer 1

Lesion studies
Brain stimulation
Electrophysiology
Functional neuroimaging

Question 2

What are the invasive and non-invasive ways of performing lesion studies?

Answer 2

Invasive
- destroy brain regions of interest
- remove/cool brain tissue
Non-invasive
- study people with incidental lesions
- use brain stimulation to temporarily impair processing

Question 3

How can we map lesions on the brain?

Answer 3

Using an MRI - allows spatial specificity and determination of causal relations

Question 4

What was the case of HM?

Answer 4

A patient who had a lesion in the hippocampus as a result of surgery for epilepsy, found they could no longer form memories

Question 5

What is a single dissociation lesion study?

Answer 5

Where a lesion in a specific region causes impairment in a specific task

Question 6

What was the case of DF?

Answer 6

Suffered CO poisoning and acquired single dissociation btw dorsal and ventral stream, impaired object perception but still has object guided action (e.g. posting a letter)

Question 7

What is the issue with using single dissociations to research the brain?

Answer 7

The tasks we are testing the participants with may not be equally as easy or may be testing the wrong skills for that region

Question 8

What is double dissociation?

Answer 8

Different tests are carried out on different regions to prove that a specific region is associated with a task

Question 9

What would a lesion in the ventral stream usually suggest?

Answer 9

impairment in discrimination

- cannot match the shape of two targets to get a reward

Question 10

What would a lesion in the dorsal stream usually suggest?

Answer 10

impairment in location

- cannot discriminate the position of a probe relative to 2 targets

Question 11

What are the Pros and Cons of lesion studies?

Answer 11

Pros
- reveal causal links between regions and functions
- high spatial precision
Cons
- low temporal precision
- low spatial precision (when incidental lesions)
- possible confounding impairment
- difficult, costly, (unethical) to experimentW

Question 12

What is invasive brain stimulation?

Answer 12

stimulation of neurones in particular brain regions by implanting electrodes

Question 13

What is non-invasive brain stimulation?

Answer 13

TMS used to stimulate neurones

tDCS can stimulate larger areas than TMS

Question 14

What does stimulating face recognition areas of a participant’s face cause?

Answer 14

Participants see faces in objects that do not normally have faces

Question 15

What does stimulating colour perception areas in the brain cause?

Answer 15

Participants see rainbow colours on single coloured objects

Question 16

How does TMS work?

Answer 16

Stimulation coil produces fast changing magnetic fields over the scalp inducing electric currents into into neural tissue

Question 17

What can stimulation of the visual cortex cause?

Answer 17

Phosphenes (light flashes)

Question 18

What can stimulation of the motor cortex cause?

Answer 18

muscle twitches

Question 19

Why is TMS described as chaotic?

Answer 19

There is no clear pattern of disruption of neurones

Question 20

What are the Pros and Cons of brain stimulations?

Answer 20

Pros
- reveals causal links between brain regions and functions
- high temporal precision and reasonable spatial precision
- relatively easy + cheap
Cons
- underlying neural mechanisms not well understood
- widespread effects possible
- cannot reach all parts of the brain with TMS

Question 21

What is electrophysiology?

Answer 21

The measuring of membrane potentials and neural firing by getting as close to the neurone as possible

Question 22

What is invasive electrophysiology?

Answer 22

single neurones recordings

Question 23

What is non-invasive electrophysiology?

Answer 23

EEGs and MEGs

Question 24

What can we measure in animals using implanted microelectrodes?

Answer 24

find a neurone’s receptive field

probe the neurone with different visual stimuli

Question 25

What is a low pass filter recording?

Answer 25

neural spiking from action potentials

Question 26

What is high pass filter recording?

Answer 26

local field potentials from presynaptic inputs changing membrane potential

Question 27

What can be done with the recordings once they have been isolated?

Answer 27

Track the occurrence of spikes over time and create a histogram

Question 28

In what cases can invasive electrophysiology be done in humans? However, what is the issue with this?

Answer 28

In epileptic patients | However, they already have altered brain function

Question 29

How do we use an EEG?

Answer 29

electrodes attached to the scalp using conductive gel | weak electrical signals are amplified and plotted across time creating a temporally precise map of cortical activations

Question 30

How do we use MEG?

Answer 30

Evoke magnetic fields by generating electrical changes in the brain Find the characteristic temporal patterns of electric currents

Question 31

What are the 3 main states of electric currents in the brain?

Answer 31

``` delta waves (asleep) alpha waves (awake) gamma waves (sensory processing) ```

Question 32

What is an ERP?

Answer 32

Event related potential - an accumulation of random neural responses

Question 33

What are the Pros and Cons of electrophysiology

Answer 33

``` Pros - high temporal resolution - high spatial precision (if invasive) - easy/cheap - yields rich info about neural dynamics Cons - low spatial precision (if on scalp) - only correlational data - no direct access to neural scalp firing (if on scalp) ```

Question 34

What does functional neuroimaging do?

Answer 34

track cerebral blood-flow to find high activation areas

Question 35

What are the 3 types of functional neuroimaging?

Answer 35

PET fMRI fNIRs

Question 36

What is a Pet scan?

Answer 36

fast decaying radioactive tracers are injected into the blood, resulting radiation is collected and spatially reconstructed to find a 3D image of where the tracer accumulates

Question 37

What are some examples of tracers?

Answer 37

fluorodeoxyglucose (glucose-like, so accumulates where glucose would i.e. high metabolic activity)

Question 38

What are some issues with PET?

Answer 38

exposes participants to radioactivity does not offer anatomical mapping of the brain temporally very imprecise

Question 39

How does fMRI work?

Answer 39

particles in the body are magnetised and stimulated with radioactive frequency pulses this energy resonates from the body creating the fMRI signal

Question 40

What is the fMRI flow diagram?

Answer 40

increased neural activity --> increased blood-flow --> oxygen removed from blood --> deoxy/oxy haemoglobin imbalance --> increased signal

Question 41

What can be said about the temporal precision of fMRI?

Answer 41

It is more precise than PET | It has several seconds of delay behind neural activations so not super precise

Question 42

What are the Pros and Cons of fMRI?

Answer 42

``` Pros - high spatial precision - allows functional and structural mapping - mostly non-invasive Cons - low temporal precision: haemodynamic lag - only correlational data - indirect activation measure - quite expensive ```

Question 43

What tracer is also used by PET used in Alzheimer studies?

Answer 43

PiB - binds to beta-amyloid