Bio - Ways of studying the brain

Question 1

What are the 4 ways of studying the brain?

Answer 1

Functional magnetic resonance imaging (fMRI)
Electroencephalogram (EEG)
Event-related potentials (ERPs)
Post-mortem examinations

Question 2

Electroencephalogram (EEG)

Answer 2

A method of recording changes in the electrical activity of the brain using electrodes attached to the scalp.

Question 3

Event-related potentials (ERPs)

Answer 3

A technique that takes raw EEG data and uses it to investigate cognitive processing of a specific event. It achieves this by taking multiple readings and averaging them in order to filter out all brain activity that is not related to the appearance of the stimulus.

Question 4

Functional magnetic resonance imaging (fMRI)

Answer 4

A technique for measuring brain activity. It works by detecting changes in blood oxygenation and flow that indicate increased neural activity.

Question 5

Post-mortem examinations

Answer 5

Ways of examining the brains of people who have shown particular psychological abnormalities prior to their death in an attempt to establish possible neurobiological cause for this behaviour.

Question 6

Explain what happens in fMRI

Answer 6

Changes in brain activity are measured while a person performs a task.

Question 7

What information is obtained from fMRI?

Answer 7

As changes in blood flow are measured in particular areas of the brain, increased neural activity can be indicated when a ppt is performing a task.

If a particular area of the brain becomes more active, there is an increased demand for oxygen in that area. The brain responds to this extra demand by increasing blood flow, delivering oxygen in the RBC.

Question 8

What can researchers do with the information obtained from fMRIs?

Answer 8

They are able to produce maps showing which areas of the brain are involved in a particular mental activity.

Question 9

What do fMRIs measure?

Answer 9

Changes in blood flow in/to the brain.

Question 10

What does an EEG measure?

Answer 10

Electrical activity in the brain.

Question 11

Explain what happens during an EEG

Answer 11

Electrodes are placed on the scalp which detect small electrical charges resulting from activity of the brain cells. When electrical signals from the different electrodes are graphed over a period of time, the resulting representation is called an EEG.

Question 12

What information is obtained from an EEG?

Answer 12

Small electrical charges are detected by electrodes placed on the scalp from the activity of brain cells. This information is collected over a period of time to produce an EEG.

Question 13

What can EEG data be used for?

Answer 13

To detect various types of brain disorder (such as epilepsy) or to diagnose other disorders that influence brain activity (such as Alzheimer’s disease).

Question 14

What would an EEG look like for someone with epilepsy?

Answer 14

The EEG readings would show spikes of electrical activity.

Question 15

What would an EEG look like for someone with brain disease and/or brain injury?

Answer 15

The EEG patterns would show overall slowing of electrical activity.

Question 16

What are the five basic EEG patterns?

Answer 16

Gamma waves, beta waves, alpha waves and theta waves.

Question 17

When would rhythmical alpha waves be recorded by an EEG?

Answer 17

When the person is awake but relaxed

Question 18

When would beta waves be recorded by an EEG?

Answer 18

When the person is physiologically aroused, their EEG pattern shows low amplitude and fast frequency beta waves. (Excited/anxious)

Beta waves are also found in REM sleep when the eyes move rapidly back and forth.

Question 19

When would delta waves be recorded by an EEG?

Answer 19

During deep sleep (when repair happens) (glymphatic cycle/dreamless) (NOT WHEN CONSCIOUS).

Question 20

When would theta waves be recorded by an EEG?

Answer 20

During light sleep/dreaming/deep meditation.

Question 21

When would gamma waves be recorded by an EEG?

Answer 21

When a person is alert, learning, problem-solving, etc.

Question 22

What type of waves would be recorded by an EEG when a person is awake but relaxed?

Answer 22

Alpha.

Question 23

What type of waves would be recorded by an EEG when a person is physiologically aroused or is in REM sleep?

Answer 23

Beta.

Question 24

What type of waves would be recorded by an EEG when a person is in deep sleep (NOT WHEN CONSCIOUS)?

Answer 24

Delta.

Question 25

What type of waves would be recorded by an EEG when a person is in light sleep/dreaming/deep meditation?

Answer 25

Theta.

Question 26

What type of waves would be recorded by an EEG when a person is alert, learning, problem-solving, etc?

Answer 26

Gamma.

Question 27

What can be seen from an EEG when a person moves from light to deep sleep?

Answer 27

The occurrence of alpha waves decreases and are replaced first by lower frequency theta waves and then by delta waves.

Question 28

Explain what ERPs are

Answer 28

Very small voltage changes in the brain that are triggered by specific events or stimuli, such as cognitive processing of a specific stimulus.

Question 29

Because ERPs are difficult to pick out from all the other electrical activity being generated within the brain at a given time, what can be done to establish a specific response to a target stimulus?

Answer 29

Many presentations of the stimulus have to be carried out and these responses are then averaged together.

Question 30

Why is it valid when measuring ERPs to average out the responses found to establish a specific response to a target stimulus?

Answer 30

Because any extraneous neural activity that is not related to the specific stimulus will not occur consistently, whereas activity linked to the stimulus will.

This has the effect of cancelling out the background neural ‘noise’, making the specific response to the stimulus in question stand out more clearly.

Question 31

What 2 categories can ERPs be divided into?

Answer 31

Sensory ERPs and cognitive ERPs.

Question 32

What are sensory ERPs?

Answer 32

Waves occurring within the first 100ms after presentation of the stimulus.

Question 33

Why are waves occurring within the first 100ms after presentation of the stimulus termed sensory ERPs?

Answer 33

As they reflect an initial response to the physical characteristics of the stimulus (detecting).

Question 34

What are cognitive ERPs?

Answer 34

Waves generated after 100ms from when the stimulus was presented.

Question 35

Why are waves occurring more than 100ms after presentation of the stimulus termed cognitive ERPs?

Answer 35

As they reflect the manner in which the subject evaluates the stimulus and demonstrate information processing (interpreting).

Question 36

What happens in the process of finding ERPs?

Answer 36

• An EEG machine is used.
• A patient repeats an action many times.
• We record ‘normal’ baseline readings.
• We can infer what electrical activity was due to the repeated action/activity (correlation).

Question 37

Explain how fMRIs are able to produce information about blood flow

Answer 37

• A ppt performs tasks inside an electromagnetic tunnel.
• A magnetic field aligns hydrogen nuclei (abundant in blood/haemoglobin(hB)).
• Radio pulse ‘flips’ nuclei, then when they realign, they release energy.
• Energy differences (gradients) are mapped using a coil.
• These are mapped onto a computer-generated frame to produce images.
• Brighter areas have more blood flow (they’re doing more work).

Question 38

What is the mapping technique used in fMRIs called?

Answer 38

BOLD - Blood Oxygenation Level Dependent activity.

Question 39

What does BOLD stand for in relation to fMRIs?

Answer 39

BOLD - Blood Oxygenation Level Dependent activity.

Question 40

Give examples of how post-mortem examinations have been used to provide evidence for the functions of certain brain areas

Answer 40

Broca’s patient Tan, who displayed speech problems when alive was subsequently found to have a lesion in the area of the brain that is now known as ‘Broca’s area’ which is an important are for speech production.

Annese et al. (2014) confirmed that HM’s inability to store new memories was linked to lesions in the hippocampus.

Cotter et al. (2001) found evidence of reduced numbers of glial cells in the (pre)frontal cortex of patients with depression. Therefore, a link has been established between psychiatric disorders, such as schizophrenia and depression, and underlying brain abnormalities.

Question 41

What are the strengths of fMRI?

Answer 41

• Non-invasive (i.e. does not involve the insertion of instruments into the body), nor does it expose the brain to potentially harmful radiation unlike other scanning techniques.
• Offers a more objective and reliable measure of psychological processes than is possible with verbal reports. It is a useful way of investigating psychological phenomena that people would not be capable of providing in verbal reports.

Question 42

What are the limitations of fMRI?

Answer 42

• Because it measures changes in blood flow in the brain, it is not a direct measure of neural activity in particular brain areas. This means it is not a truly quantitative measure of mental activity in these brain areas.
• Critics argue that fMRI overlooks the networked nature of brain activity, as it focuses only on localised activity in the brain. They claim that it is communication among the different regions that is most critical to mental function and this can’t be seen on fMRI yet (Connectome project).
• Correlational data only (third variable problem).

Question 43

What are the strengths of EEG?

Answer 43

• Provides a recording of the brain’s activity in real time rather than a still image of the passive brain. This means that the researcher can accurately measure a particular task or activity associated with it.
• Useful in clinical diagnosis, e.g. by recording the abnormal neural activity associated with epilepsy. Epileptic seizures are caused by disturbed brain activity, which means that the normal EEG reading suddenly changes. This helps diagnose whether some experiencing seizures has epilepsy.
• Low-cost option for research.

Question 44

What are the limitations of EEG?

Answer 44

• Can only detect the activity in superficial regions of the brain so it cannot reveal what is going on in deeper regions such as the hypothalamus or hippocampus. Electrodes can be implanted in non-humans to achieve this, but it is not ethically permissible to do this with humans because this would be too invasive.
• Electrical activity can be picked up by several neighbouring electrodes, therefore the EEG signal is not useful for pinpointing the exact source of an activity. As a result, it doesn’t allow researchers to distinguish between activities originating in different but closely adjacent locations in the brain. (Not very sensitive).
• Correlational data only (third variable problem).

Question 45

What are the strengths of ERPs?

Answer 45

• They provide a continuous measure of processing in response to a particular stimulus which make it possible to determine how processing is affected by a specific experimental manipulation, for example during presentation of different visual stimuli.
• An ERP can measure the processing of the stimuli even in the absence of a behavioural response. ERP recordings make it possible to monitor ‘covertly’ the processing of a particular stimulus without requiring the person to respond to them (we can tell when someone is thinking).

Question 46

What are the limitations of ERPs?

Answer 46

• Correlational data only (third variable problem).
• ERPs are so small and difficult to pick out from other electrical activity in the brain so it requires a large number of trials to gain meaningful data. This places limitations on the types of questions that ERP readings can realistically answer. A large number of trials also means that it is time consuming and expensive.
• Only sufficiently strong voltage changes generated across the scalp are recordable. Important electrical activities occurring deep in the brain are not recorded, meaning that the generation of ERPs tends to be restricted to the neocortex (only useful for neocortical measurements).

Question 47

What are the strengths of post-mortem examinations?

Answer 47

• Allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with the sole use of non-invasive scanning techniques such as fMRI and EEG. For example, it enables the researchers to examine deeper regions of the brain such as the hypothalamus and hippocampus.
• Harrison (2000) claims that post-mortem studies have played a central part in our understanding of the origins of schizophrenia. He suggests that as a direct result of post-mortem examinations, researchers have discovered structural abnormalities of the brain and found evidence in changes in neurotransmitter systems, both of which are associated with the disorder. (Application.)
• All regions of the brain are available for study.

Question 48

What are the limitations of post-mortem examinations?

Answer 48

• Because people die in a variety of circumstances and at varying stage of disease, these factors can influence the post-mortem brain. Similarly, the length of time between death and the post-mortem (post-mortem delay), degradation of brain tissue, diseases, drug treatments and age at death/age of brain are possible confounding influences of any difference between cases and controls.
• This approach is limited because it is retrospective as the person is already dead. As a result, the researcher is unable to follow up on anything that arises from the post-mortem concerning a possible relationship between brain abnormalities and cognitive function. (A snapshot only - the person is dead so we can’t follow up or ask for history.)
• Correlational data only - can never be tested.